-•
UNIVERSITY OF IBADAN LIBRARY
'CHEMOPREVENTIVES: UNTAPPED GENII
THAT COMPROMISE THE SCIENCE OF THE
"KILLERS"
An inaugural lecture delivered
at the University of Ibadan
on Thursday, 03 March, 2016
By
EBENEZER OLATUNDE FAROMBI
Professor of Biochemistry and Molecular Toxicology
Faculty of Basic Medical Sciences
University of Ibadan
Ibadan, Nigeria
UNIVERSITY OF IBADAN
UNIVERSITY OF IBADAN LIBRARY
Ibadan University Press
Publishing House
University of Ibadan
Ibadan, Nigeria.
© University of Ibadan, 2016
Ibadan, Nigeria
First Published 2016
All Rights Reserved
ISBN: 978 - 978 - 952 - 814-1
Printed by: Ibadan University Printery
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The Vice-Chancellor, Deputy Vice-Chancellor (Admini-
stration), Deputy Vice-Chancellor (Academic), The Registrar
and other Principal Officers, Provost of the College of
Medicine, Dean of the Faculty of Basic Medical Sciences,
Dean of the Postgraduate School, Deans of other Faculties
and of Students, Distinguished Ladies and Gentlemen.
As I give this lecture on behalf of the Faculty of Basic
Medical Sciences of the College of Medicine, I exalt, glorify
and magnify the Almighty God, the King of kings, the Lord
of lords; the One who was, who is and who is to come, the
Giver and Preserver of life, the Source of wisdom and
knowledge and whose inspiration gives men understanding.
This lecture is coming up about ten years since I was
promoted to the grade of a Professor of Biochemistry of this
University. I am grateful to the Dean of our Faculty for giving
me the opportunity to stand on this podium today to address
the Vice-Chancellor and this distinguished audience within
and outside the discipline of Biochemistry.
The first inaugural lecture from the Department of
Biochemistry titled 'Power House of the Living Cell' was
delivered by Professor Enitan Abisogun Bababunmi in 1982.
The second lecture was delivered by my academic father,
Professor Godwin Onyenoro Emerole, with the title
'Xenobiotics in Biochemical and Cellular Dysfunction'. Ten
years later, Professor Anthony Osaigbovo Uwaifo delivered
the third lecture titled, 'Cancer: A consequence of Cellular
Break-down of Law and Order'. Professor Olufunso Olabode
Olorunsogo delivered the fourth lecture in 2010 with the title
'From Power House to Pumps: Memoirs of a Mitochondriac'.
Today with all sense of humility, I present the 5th inaugural
lecture titled, "Chemopreventives: Untapped genii that
compromise the science of the "Killers".
Introduction
My journey into Biochemistry and subsequently making
academic a career was by divine arrangement. I graduated as
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the best student at both the BSc and MSc levels In
Biochemistry and as such had the option in the 80's of
working in companies and industries with better pay as
against my initial salary of less than W500 per month when I
joined the services of this University. I recall that the Head of
Department at that time, Professor Anthony Uwaifo, while
descending the staircase of the old Biochemistry building,
met me around 5 pm in the month of December 1989 and
said, "Farombi, I'm going to recommend you for a job in the
Department". I replied and said, "Sir, I did not apply for any
job". He told me that the Departmental Academic Board just
had a meeting and I was adjudged the best MSc student and
that it is the tradition of the Department to always retain the
best. I was thrilled and speechless about this comment. After
sleeping over the information, it was impressed on me by the
Spirit to take the job. I stand tall before you today to the glory
of God Almighty, I have no iota of regret for venturing into
the discipline of Biochemistry and making academics a
career. As stated in the Holy Bible in Jeremiah 10: 23, "The
way of a man is not in himself, it is not in man that walk to
direct his steps".
Mr. Vice-Chancellor Sir, since joining the Department
twenty six years ago I have supervised and trained one
hundred and fifty MSc students, nineteen PhD students and
several BSc students. Two of my former students are
Professors, another is an Associate Professor and many others
occupy senior positions in various industries, research
institutes and oil companies across the country and abroad.
The Department of Biochemistry, University of Thadan
has been very outstanding in teaching, research and admini-
stration since its' inception. Being a service Department, it
occupies a prominent position in the College of Medicine and
the University. The research capacity of the Department was
further enhanced in 1979 when four research sections were
created namely Membrane Biochemistry, Cancer Research,
Nutritional and Industrial Biochemistry and Drug Metabolism
and Toxicology Units. Over the years these four Units have
advanced research in their specialized areas. I have the
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opportunity of being trained by one of the older generation
and a foremost Biochemist in the person of Professor Godwin
Emerole in the area of Drug Metabolism and Toxicology.
Today, I shall present some aspects of research conducted in
this field.
Toxicology of Therapeutic Drugs
Plasmodium malaria, caused by Plasmodium falciparum,
Plasmodium vivax, Plasmodium ovale or Plasmodium
malariae is a serious disease affecting most of tropical Africa.
About 3.3 billion people are at risk of malaria worldwide and
about 215 million cases occur yearly with an estimated
mortality of about 1 million (WHO 2013). Today, the efforts
directed at controlling malaria are met with a series of
daunting setbacks. While antimalarial drugs are becoming
increasingly resistant to emerging strains of Plasmodium,
vaccines so far developed have not been able to confer
sufficient protection against the parasite. Nonetheless,
chemotherapy, which is relatively cheap and accessible to
most patients, still remains the most reliable remedy against
the infection.
Amodiaquine and Chloroquine which belong to the class
of 4-amino quinolines are widely used in the malaria endemic
tropical regions of the world in the prophylaxis and treatment
of malaria. Chloroquine in particular has wide therapeutic
properties including analgesic, antipyretic and anti-
inflammatory activities. These properties endeared chloro-
quine as the drug of choice to a number of countries in the
tropics where malaria is endemic.
The current use of combinations of drugs to eradicate
infection has raised serious concerns about the possibility of
drug-drug interaction, which may potentiate toxicity. This
development, therefore, necessitates judicious and efficient
management of the few available antimalarial drugs. Both
chloroquine and amodiaquine have still not left Nigeria
market for chemosuppression and radical cure of malaria
because they are cheap, rapidly effective and readily
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available. Mefloquine, a quinoline methanol and halofantrine
(HF), a phenanthrene methanol are two antimalarials
introduced into the market after chloroquine and
amodiaquine. Both have advantageous pharmacologic actions
that require fewer doses thereby enhancing compliance.
Due to the multi drug resistant strains of Plasmodium
falciparum that have emerged worldwide in recent times, all
these antimalarial drugs have lost their potency and ability to
radically cure malaria especially when used singly. Therefore,
WHO recommended the use of Artemisinin Combination
Therapy (ACT) as first line drugs for treating malaria even
though some resistance to these drugs have also been reported
in certain parts of the world especially South East Asia. The
antimalarials are known to affect a wide range of biochemical
processes in the living cell.
Our research unit in Biochemistry Department, named
Drug Metabolism and Toxicology Research Laboratories,
which recently metamorphosed to Molecular Drug
Metabolism and Toxicology Research Laboratories, is
reputed for its unique research and contribution to the
Toxicology of Therapeutic Drugs. Following the earlier
report of Emerole and Thabrew in 1983 on the interference of
Chloroquine on drug metabolism, we investigated the
changes in microsomal drug oxidizing enzymes, and
microsomal lipids in rats treated with therapeutic doses of
three structurally-related antimalarial drugs, Amodiaquine,
Halofantrine and Mefloquine. We reported that these drugs
inhibited the selected phase 1 drug oxidizing enzymes aniline
hydroxylase, p-nitroanisole O-demethylase and
pentoxyresorufin O-dealkylase (fig. 1) and interfered with
microsomal lipids to varying extents, and this was related to
the structural differences in the compounds (Farombi et al.
2000a).
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PROD
**
CT MQ CT MQ CT MQ
AQ HF AQ HF AQ HF
Fig. 1: Effects of therapeutic doses of antimalarial drugs on the activities
, of rat microsomal aniline hydroxylase, p-nitroanisole O-demethylase
and pentoxyresorufin O-dealkylase activities. * Significantly different
from control, P<O.OOl; **significantly different from control,
P<0.OO5; CT, control; AQ, amodiaquine; MQ, mefloquine; HF,
halofantrine; AH, aniline hydroxylase; PNOD, p-nitroanisole 0-
demethylase; PROD, pentoxyresorufin O-dealkylase. Source:
Farombi et al. 2000.
A major event in malaria infection is increased production
of highly Reactive Oxygen Species (ROS) (Wozencraft et al.
1984). A number of studies have demonstrated the
susceptibility of erythrocytes infected with the human
malarial parasite P. falciparum to oxidant-mediated damage
(Wozencraft et al. 1984). Increased production of ROS in the
whole blood was observed in Plasmodium vinckei-infected
mice. Based on the ability of Fe2+, ascorbate and H202 via
Fenton and Haber-Weiss reactions to generate ROS, we
investigated the role of these species in amodiaquine,
halofantrine and mefloquine-induced oxidative damage in
rats. We reported that the three antimalarial drugs induced
lipid peroxidation and the effect was exacerbated in the
presence of ROS (Farombi et al. 2001). This observation
suggests that antimalarial drugs could exacerbate lipid
peroxidation especially in conditions that result in an
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elevation of ROS and the data also present a need for free
radical control during malaria chemotherapy and a challenge
for drug design in the future control of Plasmodium malaria.
In addition, we showed that single and multiple doses of
amodiaquine altered enzymatic and non-enzymatic
antioxidant defense system and thus the relevance of this
observation to continuous exposure to amodiaquine whether
as single drug or even as combination therapy such as
artesunate-amodiaquine therapy should be considered
(Farombi 2000a). In another study involving humans, we
showed that chloroquine induced oxidative stress and altered
enzymic and non-enzymic antioxidant defense in the host and
this effect was exacerbated in Plasmodium falciparum
infected patients administered with the drug (Farombi et al.
2003). The implication of this study on the tissues, especially
in malaria patients undergoing chloroquine treatment on a
prolonged basis, warrants caution and supplementation with
dietary antioxidant regimen.
Antimalarials and Genotoxicity
A number of studies have indicated the possibility of
chemotherapeutic agents to induce mutagenicity apart from
damaging tissue lipids and proteins. For instance, Fasunon
and Uwaifo (1989) reported induction of prophage in E. coli
D21 and D22 and chloroquine was demonstrated to induce
frame shift mutation in E. coli and Salmonella typhimurium
(Obaseki-Ebor and Obasi 1986). During my second post
doctoral exposure at the Department of Pharmacology,
Panum Institute, University of Copenhagen, Denmark with
Dr. Lars Dragsted and Professor Stefen Loft as my
Preceptors, I was introduced to a novel technique called
"Comet assay" for assessing genotoxicity of environmental
chemical compounds including therapeutic drugs. Following
my interest in the toxicology of antimalarial drugs, I decided
to set up experiments to investigate the possible genotoxic
potential of the antimalarials, which we have studied at the
cellular level.
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The comet assay, or single-cell gel electrophoresis, is a
popular tool for the measurement of DNA damage in
individual cells. It has many applications, including
measuring chemically-induced DNA damage and predicting
the genotoxicity of potentially mutagenic and carcinogenic
substances (Hartman and Speit 1995). It. is also used for
detecting DNA double-strand breaks, alkali-labile sites such
as apurinic/apyrimidinic sites and DNA-protein crosslinks
(Tice et al. 2000). In this connection, we investigated the
genotoxic potentials of chloroquine using DNA strand breaks
as endpoints in rat liver cells evaluated by the comet assay
(figs. 2 and 3). Also, the genotoxicity of amodiaquine,
halofantrine and mefloquine was evaluated. We also assessed
the role of oxidative DNA damage in the genotoxicity by
employing DNA repair enzymes endonuclease III (Endo ill),
which converts oxidized pyrimidines into strand breaks and
fonnamidopyrimidine-DNA glycosylase (FPG), which
removes specific modified bases from DNA to create apurinic
or apyrimidinic sites that can be detected by the comet assay.
Finally, we studied mechanisms underlying the genotoxic
action of the drugs, by exploring role of free radical
scavengers.
Our results showed that chloroquine, amodiaquine,
halofantrine and mefloquine induced genotoxicity to varying
extents and that ROS might play a role in DNA-damaging
activities of the drugs (Farombi 2005, 2006). These data are
very significant and will be important in considering the
relative value of chemically-related antimalarials that are
under development for radical cure of malaria in endemic
zones of the world. According to WHO and subsequent
adoption by Nigeria government on the use of artemisinin-
based drugs as drug of choice owing to drug resistance, our
recent studies on artemisinin especially at overdose warrants
caution and regulation on its use. For instance, we showed
that artemisinin decreased sperm quantity and quality with
oxidative damage in the epididymis of rats treated with
overdose of the drug (Farombi et al. 2014).
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This study draws caution on the indiscriminate use, abuse
and patients' noncompliance to normal prescription of
artemisinin and its derivatives and as such healthcare
providers in fertility clinics should advise patients to adhere
to artemisinin prescription to reduce the risk of infertility
especially in malaria-endemic countries. In the female rats,
artemisinin in the absence of malarial parasite infection
induced hormonal imbalance (decreased follicle-stimulating
hormone and increased progesterone levels) and oxidative
damage in erythrocytes and uterus but spared the ovary of rats
(Farombi et al. 2015). Mr. Vice-Chancellor Sir, it is easily
seen from our series of mechanistic studies on the
antimalarials that these drugs are known to 'kill' malaria
parasites but host cells are not exempted in their activities.
80
70
60
...: 50
zc
.s 40
]j
~ 30
20
10
0
o 25 50 75 100 150 200 400 600 800 1000
Concentration of chloroquine QLmollL)
Fig. 2: Dose-dependent effect of chloroquine and no treatment (control) in
rat liver cells. DNA damage (strand breaks) was measured as the
percentage of tail DNA in the alkaline comet assay in rat liver cells
treated with chloroquine (0-1000 umol/L) compared with untreated
cells (control). Values are mean ± SO of 5 determinations. Source:
Farombi 2006.
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120 IoIIllII DNASBENDO [[I Sites
E:2:l FPG sites
100
-< 80
;Z;
~
...~.f! 60
40
20
0
0 100 250 500 o 100
CQ (J.lM)
Fig. 3: DNA damage in rat liver cells exposed to chloroquine (CQ) at
370C with post treatment with endonuclease III (ENDO III) and
formamidopyrimidine-DNA glycosylase (FPG). DNA damage was
measured as percentage of tail DNA. SB is strand breaks. Values are
mean ± SD of 5 determinations. Hydrogen peroxide (H202) at a
concentration of (100 umol/L) was used as positive control. Source:
Farombi 2006.
Environmental Toxicology Research
Diesel Exhaust Particles and Lung Cancer
Air pollution caused by diesel engine exhaust is a potential
environmental risk factor for human health. Diesel exhaust
particles (DEP) have a diverse mixture of chemicals including
various Polycyclic Aromatic Hydrocarbons (PAHs), and
nitrated PAHsadsorbed to the particle surface possess
mutagenic and carcinogenic potentials (SCF 2002). Diesel
exhaust (DE) has been shown to be a pulmonary carcinogen
in experimental animals following inhalation (Mauderly et al.
1987). PAHs and nitro-PAHs adsorbed to the particle surface
can form bulky DNA adducts and an increased level of DNA
adducts in rat lung following inhalation exposure to DE.
Also, DNA strand breaks can be induced by PAHs. The
carcinogenic effect has been associated with an inflammatory
response provoked by particle overload. DNA adducts and
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ROS generated by DE are also thought to play an important
role in the induction of mutations. The primary route of
exposure to DEP is inhalation of the particles resulting in
absorption via the respiratory tract. Through the action of
clearance mechanisms and depending on size, shape etc.,
particles may be transported out of the respiratory tract, into
the oral cavity and swallowed. Due to the atmospheric
deposition of particles, crops may also be contaminated with
DEP. Oral route of exposure to DEP in promoting lung
carcinogenesis was not well understood by researchers and
this later became an issue for me and other scientists in the
field of chemical carcinogenesis, to resolve.
Mr. Vice-Chancellor Sir, I was a recipient of UNESCO-
MCBN Fellowship in 2001 following recommendation by
Professor GB Ogunmola of Chemistry Department to
Professor Angelo Azzi, who was the International Chairman
of the Fellowship Board at that time. I recollect that it took a
long time after I had applied and was recommended before
the fellowship was finally approved. Then, destiny took me to
Mauritius in July 2001 as one of the speakers at the Society
for Free Radical Research (SFRR-Africa) Conference where I
met in person Professor Angelo Azzi. It was during breakfast
one morning where I sat close to the Professor that I
interacted with him and discussed the application. After the
discussion, he gave me his complimentary card and told me
to remind him about the application after the conference. He
further told me he was very pleased with my presentation at
the SFRR conference and that he would give further support
to my research. Four months after meeting Angelo Azzi, I
received an award letter to travel to the Institute of Food
Safety and Toxicology, Soborg, Denmark. I had planned to
work on another project but my host Professor Lars Dragsted
who later became my very good friend introduced me to the
project funded by the Danish Research Council and the
Danish Ministry of Health, Research Center for
Environmental Health on the role of oral exposure to DEP in
lung cancer. It was a great delight for me to be among the
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early researchers who investigated gastrointestinal
exposure to DEP in lung carcinogenesis. Working with
three giants in the field of chemical carcinogenesis-Dr. Lars
Dragsted at Soborg, Professor Steffen Loft at Panum Institute,
Copenhagen and Professor Herman Autrup of Aarhus
University, Denmark whom I met for the first time in 1999 at
the Pan African Environmental Mutagen Society (PAEMS)
conference in Harare ably organized by Professor Julia
Hasler, we investigated whether the lung is a particularly
sensitive organ for DNA damage following gastrointestinal
exposure to DEP. Employing the Comet assay, 32p_post
labeling technique and mutation analysis, we reported that the
level of DNA strand breaks increased significantly at all dose
levels of DEP exposure while the level of DNA adducts
increased significantly only at the intermediate dose levels
(fig.Aa).
Similarly, the number of oxidized DNA bases measured
as endonuclease III and fapyguanine glycosylase (FPG)
sensitive sites increased at the intermediate dose levels while
the induction of DNA damage by DEP exposure did not
increase the expression of the repair genes OGG 1 and
ERCCI at the mRNA level (fig. 4b) (Muller, Farombi et al.
2004). Our study indicated that the lung is a sensitive target
organ for primary DNA damage following oral exposure to'
DEP. The results of the study caution on the human exposure
to environmental pollution resulting from carcinogenic
compounds in exhaust particles from worn out engines.
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x 10.6
• (Al OGGI
N2Lrn,be-r o-f D-NA-a-d<i-Jct-s {-1r:-fl n-ucl-&o~tide~s ----_.
ill (B) ERCCI
'"
20
10
o 0.2 0.8 2 8 20 80
DEP (rrglkg) o 0.2 0.8 2 8 20 80DEP(mg.oIcg)
Fig. 4: (a) Level of DNA adducts in lung of Big Blue® rats after oral
administration of DEP for 21 days. Values are shown as mean ± S.D. (n
= 6). lilP< 0.05 as compared to control; (b) The expression of (A) 0001
and (B) ERCC1 mRNA in lung of Big Blue® rats after oral
administration ofDEP for 21 days. Values are shown as mean ± S.D., n =
6. The expression are normalized to 18S or mRNA level. Source: Muller
et al. 2004.
Environmental Chemicals and Reproductive Toxicity
On returning to Nigeria in 2002, my interest was further
stimulated in research activities involving environmental
compounds and how they affect specific target organs. First,
my attention was drawn to the recent scientific findings on
human reproduction which revealed that infertility may affect
15-20% of couples in industrialized countries (Oehninger
2001) compared with 7-8% of couples during the early 1960s
and which has become a global health concern in recent
decades following reports of the adverse effects of certain
environmental chemicals on reproductive function. Male-
factor infertility accounts for up to half of all cases of
infertility and affects one in twenty men in the general
population (McLachlan and de Krester 2001). Giwa-Osagie
(2003) reported that of adult couples in African countries, 10-
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25% are subfertile, and male-factor infertility accounts for
30-40% of these cases. According to his report, Nigeria has
approximately 12 million infertile persons. Based on the
avalanche of information on the possible role of
environmental chemical compounds in male reproductive
dysfunction, I engaged two MSc students Mr. Isaac Adedara
and Mr. Sunny Abarikwu to study in my laboratory the
influence of di-n-butylphthalate, a compound widely used as
a plasticizer in cellulose plastics, as a solvent for dye, and for
a variety of consumer products on male rats. I am happy to
report that these two gentlemen who are now established
investigators in the field of reproductive toxicology earned
PhD degrees under my supervision and they came out
excellently well. For instance we published 9 articles in
highly focused and specialized international journals in
Andrology from the thesis of Dr. Abarikwu. These
publications are reference points today on Atrazine
reproductive toxicity. Dr. Adedara is a Lecturer 1 with me in
UI and Dr. Abarikwu is presently a Senior Lecturer in the
University of Port Harcourt. In collaboration with my good
friend, Professor Oyeyemi of Veterinary Reproduction and
Surgery, we reported the testicular toxicity of
Di-butylphtalate in male rats (Farombi et al. 2007).
Bonny Light Crude Oil Toxicity
Our next series of research works involved the reproductive
toxicity of Nigerian Bonny light crude oil produced in the
Niger Delta basin of Nigeria. Accidental or occupational
pollution of the environment with petroleum is of great health
concern especially in the Niger Delta region of Nigeria.
Significant data have been collected from monitoring the
effects of unintentional oil spills, providing "real-world"
environmental information. Both animals and humans may be
exposed directly or through the food chain. In actual fact, one
of my PhD students, now Head of Department of
Biochemistry in one of the South Eastern Nigerian
universities, Dr. Ebokaiwe showed that humans can be
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exposed to BLeO via the food chain (Ebokaiwe 2013).
Interestingly, humans can be exposed to BLeO deliberately
via oral route as some people believe in its folkoric use in the
treatment of gastrointestinal disorders and convulsion in
children.
Preliminary report of Orisakwe et al. (2004) implicated
BLeO in testicular toxicity but information regarding its
mechanisms of reproductive toxicity was lacking until we
demonstrated for the first time that BLeO exposure induced
significant reduction in testes weights, epididymal sperm
counts, testicular sperm number, daily sperm production with
increased oxidative stress (fig. 5) and sperm abnormality
(Farombi et al. 2010). The quantification of tissue
concentrations of biometals revealed bio-accumulation of
toxic metals, including nickel, lead, copper and iron, in testes
of rats (fig. 6) exposed to BLeO (Adedara et al. 20 13a).
Thus, ROS generation in tandem with heavy metal
bioaccumulation (especially in the testes) through our data
have been implicated in BLeo testicular toxicity.
In order to elucidate the mechanism of reproductive
toxicity of BLeO, we investigated the influence of BLeO on
steroidogenesis, hypothalamic-pituitary-testicular axis and
pituitary-thyroid axis functions in Bl.Cfr-treated rats. This
was the first study to evaluate the effects of BLeO on the
endocrine system. Using Western blot technique, we showed
that BLeO exposure suppressed the expression of steroid
acute regulatory protein which mediates the rate-limiting step
in steroid hormone biosynthesis by facilitating cholesterol
transfer from the outer to the inner mitochondrial membrane,
and androgen-binding protein expression, a secretory product
of Sertoli cells which regulates spermatogenesis by
specifically binding to testosterone with high affinity (fig. 7).
This protein is considered as a biological marker for Sertoli
cell function.
The effect of BLeO on these proteins was accompanied
with concomitant decrease in 313-~hydroxysteroid dehydro-
genase (HSD) and 17~-hydroxysteroid dehydrogenase
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activities (figs. 8a and b) and decreased plasma concentra-
tions of follicle-stimulating hormone, luteinizing hormone,
prolactin and intratesticular testosterone and elevated
thyrotropin, triiodothyronine and thyroxine (Adedara et al.
2014a, Ebokaiwe et al. 2015a). Our recent report showed that
the interference of BLCO on endocrine function is
accompanied by generation of ROS in testicular system
thereby enhancing oxidative stress (Ebokaiwe et al. 2015a).
The data indicate that undue exposure to BLCO has an
inhibitory effect on testicular steroidogenesis and may
involve its disruptive effect on the brain-pituitary-testicular
axis thus highlighting the potential risk to public health for a
population where, unfortunately, oil spillage occurs
frequently.
A seD B .GST
IDCon"'" C2OOm9'I<G.«lIInIo'ko B8DOmo1<o I
TESTES SPERII TESTl'S SPERII
CAT GSH
D.tS
0.14
& 0.12
I 0.,
i 0.01
I::
0.02
TmES SPEIIII
Fig. 5: Effect ofBLCO on the activities of SOD, CAT, and aST and aSH
level in rat after 7 days. Each bar represents mean ± SD of 12
animals. *Values differ significantly from control (p<O.05). Source:
Farombi et al. 2010.
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1200
g
c -.'~. ,I-~~, ..~.-.~.- ...'''-~''-.."~la 1000 m.. ~ rnn arb ~Fe :llCu ~Nis'I>
.!: 800 :·fii
""2 un::::
~
•c
600 ili~
'f•i
l 400
<••II
!!
~ 200
c•.•.
0
Blood Liver Testes
Fig. 6: Relative percentage change in metal concentrations in the tissues
of rats exposed to bonny light crude oil. Source: Adedara et al. 2013.
(A) • __ - StAR, 46 kDa (8) ~ _ ASP,30kDa
1 Actin,42kDa .-. ~ ~ Actin, 42 kDa
1.2 1.2
c 1.0
.Q
'e"
[~ 0.8
~::J
c
-ae;
>
"e
-
0.6
c.-€
.~~ 0.4
S
£ 0.2
0.0
Control 200mglkg 800mglkg Control 200mglkg 800mglkg
Fig. 7: Effects of Bl.Ct) on StAR (A) and ABP (B) expression in adult
male rats (n.7). Data are expressed as mean ± SD. *Values differ
significantly from control (p<0.05). Source: Adedara et al. 2014a.
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3p -HSD
1,6. to
llh 24h 72h Oh 6h i?-h Un 7211
Time after treatment with BLeD Time after treatment with BLCD
Fig. 8: (a) Effect of BLCO on the activity of 313-HSD in the testis of adult
rats over different time points. (rr=l) per time point. *; statistical
significance at p<O.05; (b) Effect of BLCO on the activity of 1713-
HSD in the testis of adult rats over different time points. (n=4) per
time point. *; statistical significance at p<O.05. Source: Adedara et al.
2014a. .
In order to fully comprehend the tOXICIty profile of
BLCO, we carried out reversibility studies in the liver of rats,
knowing the ability of the adult liver to restore its function
and mass after injury or extended resection. Thus, considering
the defence capacity of the body, the question then arises as
to whether hepatic damage resulting from exposure to BLCO
is transient or permanent. In rats treated with BLCO for 21
days and treatment withdrawn for another 21 days, there was
significant hepatotoxicity and increased oxidative stress,
which was not reversible upon withdrawal of treatment within
the time course of investigation in male rats (Adedara and
Farombi 2012). These results are novel and have significant
implications for human health especially, if extrapolated to
individuals using BLCO as folklore medicine.
Bl.Ct) and Apoptosis
Cell death by apoptosis is a part of normal development and
maintenance of testicular homeostasis. During various stages
of spermatogenesis, an adequate amount of germ cells are
eliminated via the process of apoptosis in order to maintain a
precise genu cell population in compliance with the
supportive capacity of the Sertoli cells. The two divergent
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pathways of testicular apoptosis namely, the receptor
mediated FasIFasL pathway and the mitochondrial-mediated
pathway play an important role in maintaining the germ cell
population. Inappropriate activation of apoptosis could
enormously jeopardize spermatogenesis and hence fertility. In
order to gain further insight into the molecular mechanisms of
gonadal toxicity induced by BLCO, using a single dose of
BLCO (800 mg/kg), we determined the levels and time-
course induction of stress response proteins and apoptosis-
related proteins like cytochrome c, caspase 3, procaspase 9,
Fas-FasL, NF-KB and TNf-a to assess sequential induction
of apoptosis in the rat testis and DNA damage assessed by
TUNEL assay. We showed that single dose exposure of
BLCO to rats resulted in a significant increase in the levels of
stress response proteins and apoptosis-related proteins and
DNA damage as revealed by time-dependent increase in the
TUNEL positive cells of testicular cells as early as 6 h
(fig. 9) (Ebokaiwe et al. 2015b). The data demonstrate that
single dose exposure of rats to BLCO induced apoptosis via
FasL and mitochondria-mediated apoptosis pathways in testis
of adult rats.
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(C) 6 hour (D) 24 hour (E) 72 hour
Fig. 9: BLCO-induced germ cell death in the testis of rats as revealed by
TUNEL assay. Representative images for TUNEL staining in
negative control (a), control (b), 6 h (c), 24 h (d) and 72 h (e) post-
treatment groups. The TUNEL-positive cells (arrows) are found in
the peripheral region near the basement membrane of the
seminiferous tubules. A time-dependent increase in the number of
apoptotic cells in the testis of BLCO-treated rats may be noted.
Source: Ebokaiwe et at. 2015b.
Atrazine Toxicity
In continuation of our works on 'killer' environmental
pollutants and contaminants as they affect human health, we
carried out a series of research works on biochemical and
molecular mechanisms of action of Atrazine in rodent
models. The herbicide Atrazine (ATZ) (2-chloro-4-
(ethylamino)-6-(isopropylamino)- s-triazine) is a widely used
broad-spectrum pesticide with selective application in pre-
and post-emergent control of weeds in corn and sorghum
fields. It has been estimated that 76.4 million pounds of ATZ
is used annually in the United States alone (Stoker et al.
2002). Besides its widespread use in the control of broadleaf
and grassy weeds in a variety of crops, ATZ is a potential
contaminant for surface and ground water sources (Koskinen
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UNIVERSITY OF IBADAN LIBRARY
and Clay 1997). United States Environmental Protection
Agency has classified ATZ as "priority A" chemical for
potential ground water contamination and it was ranked the
highest of 83 pesticides for potential ground water
contamination (Abarikwu and Farombi 2012). It has been
estimated that between two and three million people who use
ground water as the source of their primary drinking water are
exposed to Atrazine contamination because of its persistence
in the environment (soil and water). In this connection,
atrazine and its metabolites have been identified in the urine
of occupationally-exposed males (Buchholz et al. 1999).
Atrazine and Reproductive Dysfuntion
Atrazine has been considered an endocrine disruptor, causing
adverse effects on reproductive function in both genders of
several mammalian and non-mammalian species (Friedmann
2002; Spano et al. 2004). For instance, the alterations in
hormone levels by atrazine have resulted in a number of
reproductive and developmental effects, including delay in
vaginal opening in the females, altered estrus cyclicity,
decreased fertility, increased pre-implantation and post-
implantation loss in animal models, inflammation of the
prostate, and possible implications for breast cancer in
women (Stoker et al. 1999). Previous studies reported the
testicular toxicity of ATZ. However, none of the previous
studies examined the mechanisms of its toxicity. We reported
for the first time, the spermatogenesis and morphological
changes of testicular and epididymal sperms in ATZ-treated
rats and that these changes occurred via mechanisms
involving oxidative stress (Abarikwu et al. 2010; Farombi et
al. 2013).
Prior to our mechanistic studies on ATZ-mediated
cytotoxicity, the cellular and molecular events involved in
ATZ-induced infertility were poorly understood. We
therefore investigated ATZ-induced transcriptional changes
in selected markers of steroidogenesis in primary cultures of
rat interstitial Leydig cells. We reported for the first time, a
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dose dependent induction in the levels of mRNA expression
of genes of steroidogenic acute regulatory protein (STAR),
cytochrome P45011A1, 3~-hydroxysteroid dehydrogenase
(3~-HSD) and other steroidogenic proteins in cells exposed to
ATZ using quantitative Real time PCR (Abarikwu et al.
2011a). In addition to these genes, the mRNA expression of
CYP17 AI, inhibin-o; (INH-a), androgen receptor (AR),
estrogen receptor-a (ER-a), and luteinising hormone receptor
(LHR) also increased (Abarikwu, Pant and Farombi 2013)
(fig. 10).
Steroidogenesis starts with the transfer of cholesterol by
STAR into the mitochondria to the site of action of CYP11A1
which then converts cholesterol to pregnenolone.
Pregnenolone is converted to progesterone by 3~-HSD and
the conversion of progesterone to androstenedione is
catalyzed by CYP17AI (Payne and Youngblood 1995). The
main control of this process occurs through the binding of
luteinising hormone to its receptor (LHR) on the Leydig cell
membrane, which is also coupled to the cyclic-AMP
signaling pathway, to stimulate the production of testosterone
de novo from cholesterol. However, we observed increased
gene expressions of the tested genes either in the presence or
absence of cyclic-AMP in the medium suggesting that ATZ
may not always require cyclic-AMP signalling to up-regulate
the expressions of steroidogenesis genes. Our data are novel
and significant and suggest the application of these selected
marker genes of steroidogenesis as indicators of short term
exposure of ATZ-induced testicular toxicity in rats interstitial
Leydig cells (ILCs).
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b
6 JNtI·a
0,:.:- 1
:i;;. 0.8 1
.~ ,
6- 0.6
.s~ 0.4 ,.#1# , •...•...i•..1.,.. •. ,
1.2 c
Fig. 10: Real-time quantitative RT-PCR analyses of Leydig cell mRNA
for (a) luteinising hormone receptor (LHR), (b) inhibin alpha (INH-
a), (c) cytochrome P450 i7 Al (CYP17 Al ) from control and atrazine-
exposed (0.5-50 Iglml) interstitial Leydig cells at 2 h post treatment.
Source: Abarikwu, Pant and Farombi 2013.
Atrazine and Neurodegenerative Diseases
The contribution of environmental contaminants to the
aetiology of neurodegenerative diseases, such as Parkinson's
disease (PD), is now being broadly recognized (Di Monte
2003). Of importance, a recent twin study for PD incidence
indicated that genetic factors do not play a major role in
causing adult onset PD (Tanner et al. 1999). While several
environmental factors have been implicated in the aetiology
of PD, the evidence for a positive relationship between PD
incidence and pesticide exposure is increasing (Lockwood
2000; Le Couteur et al. 1999). Specifically, atrazine was
reported to work as a potential contributory risk factor for
Parkinson's disease and other neurological disorders where
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dopamine levels were depleted (Filipov et al. 2007). Many of
the toxicological studies conducted so far have focused
primarily on the effects of ATR on the endocrine and
reproductive systems. Neurotoxic potential of ATR,
especially the underlying molecular mechanism, was poorly
understood. In this connection, we selected the SH-SY5Y
human neuroblastoma cell line as a model system to define
the mode of cell death-induced by ATR in a human
dopaminergic system by exploring novel markers of oxidative
damage and apoptosis. We reported in SH-SY5Y cells that
ATR induced generation of reactive oxygen species (ROS),
cell death and cell proliferation.
Furthermore, ATZ increased leakage of lactate dehydro-
genase (LDH) , inhibited cellular LDH activity, mediated
nuclear changes associated with apoptosis; including nuclear
fragmentation, condensation, DNA laddering, increased
caspase-3 activity and changes in the expressions of p53,
Bax, Bcl-2, p21, and mRNA levels of caspase-3 and caspase-
9 (Abarikwu, Farombi and Pant 2011). Our data demonstrate
that ATZ mediates apoptosis by mechanisms involving ROS
generation mediated through the Bax/Bcl-2 ratio and caspase-
3-dependent pathway (Abarikwu and Farombi 2015). Using
Flow cytometry, we confirmed the involvement of ROS in
ATZ-induced apoptosis in PC12 cells (a rat
pheochromocytoma), another cell possessing most of the
functional expressions of neuronal cells used extensively in
neurobiology studies (Abarikwu, Farombi, Kashyap and Pant
2011).
Municipal Landfill Leachates and Toxicity
Hazardous wastes are those that hold a substantial potential
risk to human health or environment when improperly
treated, stored, transported, disposed off or otherwise
managed. Waste could be classified as industrial, biomedical
and municipal solid waste (Bhargav et al. 2008). The
increasing solid waste generation in and around major urban
centres in Nigeria now (especially in Lagos metropolis,
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UNIVERSITY OF IBADAN LIBRARY
Ibadan and Kano) due to industrial growth and rural-urban
migration, has been one of the biggest environmental
challenges (Farombi et al. 2012). Landfilling is a common
method for the management of municipal solid waste in many
developing countries. For instance, Olushosun landfill-a site
situated at an excavated site North of Lagos metropolis in
Ojota, Lagos State, has been identified. The site is surrounded
mostly by middle-density residential areas with pockets of
low and high-density residential areas and has been reported
to receive more commercial and mixed industrial wastes than
any other landfills in Lagos (Olorunfemi 2011).
A major problem arising from uncontrolled landfill/waste
dumpsites is the generation of leachates caused by bio-
chemical decomposition of organic or biodegradable portion
of the wastes and the percolation of rainwater through the
wastes (Farombi et al. 2012). Leachates resulting from
uncontrolled landfill sites are often a common source of
pollution for groundwater aquifers and surface waters. For
example, the groundwater sources within 2 km radius of the
Olushosun landfill has been reported to be contaminated by
heavy metals which was largely associated with the
dispersion of chemical constituents from leachate produced at
the landfill (Oyeku and Eludoyin 2010).
We reported that the physicochemical characteristics
including total alkalinity, total acidity, total hardness,
biochemical oxygen demand and chemical oxygen demand,
as well as the concentrations of copper, lead, cadmium,
arsenic, cobalt, chromium and mercury of Olushosun
municipal landfill leachates (OMLL) were higher than
acceptable limits by international regulatory authorities
(Farombi et al. 2012) and when administered to rats at
different doses significant hepato-toxicity was observed. The
toxic chemicals such as heavy metals and organic compounds
that are present in leachates could be assimilated by aquatic
species, pass through the food chain and bioaccumulate upon
long-term exposure with potential implication for humans
who depend on aquatic products as sources of food. The
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deleterious influence of leachates from landfills on aquatic
and human health is underscored by our studies on Ogun
River, which flows in Ogun State of Nigeria and located to
two heavily industrialized cities Lagos and Sango-Ota in
Nigeria. The river serves as sources of drinking water, fishing
and other domestic uses for the population.
Using Bulk Scientific Atomic Absorption Spectro-
photometer, we reported marked accumulation of the metals
in the organs of African cat fish (Clarias gariepinus) from the
Ogun River. Heavy metal accumulation was associated with
alteration in the antioxidant enzymes of the fish and induction
of lipid peroxidation (Farombi et al. 2007). This study
therefore provides a rational use of biomarkers of oxidative
stress in biomonitoring of aquatic pollution. Mr. Vice-
Chancellor Sir, I am pleased to report that this paper
published in International Journal of Environmental Research
and Public Health based in Basel, Switzerland has been cited
up to 500 times excluding self citations and remains a
reference paper for most researchers worldwide in Aquatic
toxicology. Subsequently we reported OMLL spermato-
toxicity in vitro (Adedara et al. 2013b).
Further insight into the mechanism of action of OMLL in
living system was revealed by our studies wherein we
reported testicular toxicity with testicular biometal
accumulation of lead, cadmium, nickel, iron, copper, (fig. 11)
oxidative stress and increased activities of marker enzymes of
testicular function with altered circulatory concentrations of
reproductive/endocrine hormones (fig. 12) (Adedara et al.
2015). The deleterious effects of OMLL within 28 days of
exposure indicated lack of reversibility of its toxicity as most
of the assessed parameters persisted after treatment
withdrawal (Adedara et al. 2014). The data if extrapolated to
humans, .present significant health implications for
individuals exposed to leachate-contaminated substances.
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IIIIIIIIControi _Control
A 0.05 ~12.5%OMLL
• i\lIJIlII25%OMLL B 1.0 • 12.5%OMLL_25%OMLL
0.04 0.8
E 0.6
0..
0.. 0.4
0.01 0.2
0.00
Cd Pb NI Fe Cu
Biomelais In the testes Blometals In the testes
Fig. 11: Levels of Cd, Pb, Ni, Fe, and Cu in testes of rats after 7 days of
exposure to OMLL. Each bar represents mean ± SD of 10 rats.
*Values differ significantly from the control (p<O.05). Source:
Adedara et al. 2013.
_Control _Control
A 16 ~12.5%OMLL ~12.5%OMLl
11'11125%OMLl _2S%OMLL
14
12 5
10 4
E 8 :g3
tI)
~6 I:
2
4
2
0 0
LH FSH Prolactin Testosterone
End points in plasma End points in plasma
Fig. 12: Plasma concentrations of LH, FSH, prolactin, and testosterone in
rats after 7 days of exposure to OMLL. Each bat represents mean ±
SD of 10 rats. *Values differ significantly from control (p<0.05).
Source: Adedara et al. 2015.
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Chemoprevention
Mr. Vice-Chancellor Sir, from the series of studies on the
science of the 'killers', it is unequivocally clear that humans
are exposed to myriad of toxic and dangerous chemical
compounds. The questions are: Is there hope for man? Is
there respite for the cells these chemical compounds kill? Is
there room for prevention of chemically-mediated diseases?
Is longevity and increase in life span a possibility in the face
of overwhelming killer chemical compounds? Finally,
judging from the influence of the killers on humans, is there
light at the end of the tunnel? In the next series of studies, I
will attempt to answer these questions.
Dietary factors continue to play a complex and
multifaceted role in the aetiology of many diseases such as
diabetes, cardiovascular disorders and cancer (Farombi 2004).
For instance, apart from cigarette smoking and chronic
inflammation and infection, nutrition accounts for up to one
third of the total cause of cancer (Sugimura 2002). Richard
Doll and Richard Peto in 1981 reported, based on statistical
and epidemiological data, that 10-70% (average 35%) of
, human cancer mortality is attributable to diet. In light of the
considerable complexity of dietary substances, it is not
surprising that in addition to mutagenic and carcinogenic
components present in the diet, there may exist anti-
carcinogenic and antimutagenic substances (Farombi 2004).
Recently, attention has been focused on
phytochemicals-non-nutritive components in the plant-
based diet that possess cancer-preventive properties (fig. 13).
There is also accumulating evidence from population as well
as laboratory studies to support an inverse relationship
between regular consumption of fruits and vegetables and the
risk of specific cancers. The results of more than 250
population-based studies, including case-control and cohort
studies indicate that people who eat about five servings of
fruit and vegetables a day have approximately half the risk of
developing cancer.
In the United States, these observations led to the
development of public-health campaigns such as the 'Five-a-
Day for Better Health' programme designed to increase the
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UNIVERSITY OF IBADAN LIBRARY
ingestion of fruits and vegetables. For a global extension of
the 'Five-A-Day' concept of boosting increased consumption
of fruit and vegetables, the WHO organized the third Biennial
'Five-A-Day' International Symposium on January 14-15
2003 in Berlin, Germany. At that meeting, Derek Yach, the
WHO Executive Director of Non-communicable Diseases
and Mental Health, said "Increasing the consumption of fruit
and vegetables is a necessary part of the effort to reduce the
growing global burden of chronic diseases including cancer."
The guidelines stated, "choose most of the foods you eat from
plant sources". Ever since, many clinical trials on the use of
nutritional supplements and modified diets to prevent cancer
and other life-threatening diseases are ongoing. It is
conceivable that in the future people might only need to take
specially formulated pills that contain substances derived
from edible plants to prevent cancer or delay its onset.
Michael Sporn was the first to coin the term
'chemoprevention' in the mid-1970s and described the
strategy of blocking or slowing the onset of premalignant
tumours with relatively nontoxic chemical substances.
Chemoprevention therefore is defined as the use of agents
(especially naturally occurring) to inhibit, mitigate, delay,
reverse or retard multistage process of chronic diseases
including cancer.
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UNIVERSITY OF IBADAN LIBRARY
Qi
,,-(
ool.~'~f\(
\ !f Of!
Ile!i¥I!Il!trnI
rct1
(~t>
H
~
,. cc,c'f.S
H,C'S""''-v''''-'''' N
o•
SIII!JIl!I'8IlIIIII
lyoopellf
Fig. 13: Representative chemopreventive phytochemicais and dietary
sources. Source: Surh 2003.
Mechanisms of Chemoprevention
Chemoprevention is a term that was originally applied to
cancer development. However, in the last two decades
chemoprevention has been extended to other chronic
degenerative diseases. For the purpose of this lecture, I shall
explain the mechanism of chemoprevention by focusing on
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UNIVERSITY OF IBADAN LIBRARY
cancer. Carcinogenesis is generally recognized as a multistep
process in which distinct molecular and cellular alterations
occur. From the study of experimentally-induced carcino-
genesis in rodents, tumour development is considered to
consist of several separate, but closely linked, stages-
tumour initiation, promotion and progression (fig. 14).
Initiation is a rapid and irreversible process that involves
a chain of extracellular and intracellular events. These include
the initial uptake of or exposure to a carcinogenic agent, its
distribution and transport to organs and tissues where
metabolic activation and detoxification can occur, and the
covalent interaction of reactive species with target-cell DNA,
leading to genotoxic damage. In contrast to initiation, tumour
promotion is considered to be a relatively lengthy and
reversible processes in which actively proliferating preneo-
plastic cells accumulate. Progression, the final stage of
neoplastic transformation, involves the growth of a tumour
with invasive and metastatic potential.
Mr. Vice-Chancellor, my involvement in chemo-
prevention dates back to 1989 during my PhD training in
Biochemistry Department as a paradigm shift from the
research on environmental toxins and carcinogens focused on
by my mentors in the Department. In this connection, my
research activities in the last 25 years have focused on the use
of naturally-occurring agents (dietary agents and indigenous
plant-based phytochemicals) with antioxidant and anti-
inflammatory properties to prevent or delay the onset of
several diseases such as cardiovascular disorders,
reproductive dysfunction, cancer (gastrointestinal, prostate,
liver), and neurological disorders, as well as understanding
their molecular mechanisms with emphasis on signal
transduction network. This area of research has enabled me to
interact and collaborate with world-class experts in the field
in countries spanning 4 continents of the world.
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Pro--carcincgoo
A.... Detoxification
U .' 0c3:-!<1.-0<) ---- ..,.••I8ecrntibr) I
@1~=:,..,.~, ~~
@~1orrmJ
llnitiatioo . Pmooq:>. IasIic{1-2 days) C<lifs@·~}·~~T
lnitiaIGd =II
I -
Fig. 14: Dietary phytochemicals that block or suppress the multistage
carcinogenesis. Source: Surh 2003.
Classes of Chemopreventives
According to the conventional classification originally
proposed by Lee Wattenberg, chemopreventives are sub-
divided into two main categories-blocking agents and
suppressing agents (fig. 14) (Wattenberg 1985). Blocking
agents prevent carcinogens from reaching the target sites,
undergoing metabolic activation or subsequently interacting
with crucial cellular macromolecules (for example, DNA, .
RNA and proteins).
Suppressing agents, on the other hand, inhibit the
malignant transformation of initiated cells, in either the
promotion or the progression stage. Chemopreventive
phytochemicals can block or reverse the premalignant stage
(initiation and promotion) of multistep carcinogenesis. They
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UNIVERSITY OF IBADAN LIBRARY
can also halt or at least retard the development and
progression of precancerous cells into malignant ones. The
cellular and molecular events affected or regulated by these
chemopreventives include carcinogen activation/
detoxification by xenobiotic metabolizing enzymes; DNA
repair; cell-cycle progression; cell proliferation, differentia-
tion and apoptosis; expression and functional activation of
oncogenes or tumour-suppressor genes; angiogenesis and
metastasis; and hormonal and growth-factor activity.
Several mechanisms have been advanced for the activities
of chemopreventives. One of such involves antioxidant and
free radical scavenging activities. I will now discuss my
research activities on naturally-occurring phytochemicals
with intrinsic antioxidant properties.
My Journey into the World of Antioxidant and Free
Radical Research
I started my journey into the world of Free Radical Research
in 1988 after interacting with one of my colleagues in the
Department, Dr. W.G Okunade who just returned from a 3
month British Council Fellowship to the Laboratory of
Professor Catherine Rice Evans of the Royal Guy Hospital
London, a lady I later met in April 1996 at the 658th
conference of the Biochemical Society in Liverpool (UK),
and who offered me the opportunity to work with her but I -
chose to go elsewhere. It was actually during my first Post-
doctoral training in the Laboratory of Dr:- George Britton at
the Department. of Biochemistry, University of Liverpool that
I delved actively into this area of'Research after reading a
fresh PhD thesis written by Dr. Alan Woodall on
'Carotenoids as Antioxidants and Free Radical Scayengers'.
After reading this thesis, I became interested and discussed
with my Preceptor who agreed that I could work on
carotenoids even though my PhD Supervisor Professor
Emerole wanted me to continue our work on the
characterization of active components in brown yam flour,
which was the thrust of my PhD thesis. Given my background
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UNIVERSITY OF IBADAN LIBRARY
training at Ibadan to work very hard and late into the night in
the laboratory, I decided to handle the two projects
simultaneously, which at the end was a very successful
endeavour. After spending about three weeks in the
laboratory, one day Dr. Britton asked 'Tunde, you are from
Nigeria and I have read from literature that your country
produces and consumes a lot of red palm oil. How can we get
red palm oil from Nigeria because studies showed that red
palm oil is rich in a- and ~-carotenes?'
As at that time no one really knew about a-carotene as an
antioxidant though some studies revealed ~-carotene as a
potent antioxidant. At that time, I remember I took two
bottles of palm oil along with me but for the purpose of
cooking vegetable soup to take 'Amala' my favourite meal.
Without wasting time I decided to give away the two bottles
of red palm oil for the purpose of research. This sacrifice has
been really rewarding and has launched me into prominence
in this important field of research.
My Contributions to Antioxidant Redox Biochemistry
(Antioxidant and Free Radical Research)
My first task was to isolate and characterize a and ~-
carotenes (which exist in the same concentrations in human
plasma-(O.I±O.2/...Imr1) from Nigeria red. palm oil using
chromatographic, HPLC and spectroscopic methods.
Antioxidant potency of other potential dietary antioxidants,
which exist in human plasma such as lycopene, lutein,
zeaxanthin and ~-cryptoxanthin had been examined but little
information existed about the potency of a-carotene. Figure
15 depicts the structures of some carotenoids. Thus, we
examined and compared for the first time the antioxidant
potency of a-carotene and ~-carotene from red palm oil in
organic solution. We showed that in organic solution
containing peroxyl radicals; a-carotene was a better
antioxidant than ~-carotene (fig. 16) (Farombi and Britton
1999a).
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UNIVERSITY OF IBADAN LIBRARY
Furthermore, using azo-initiated peroxyl radical
peroxidation of egg-yolk phosphatidylcholine, a membrane
model, we confirmed the superiority of a-carotene as
antioxidant over I3-carotene (Farombi and Britton 1999b).
Based on the chemical configuration of the two compounds it
was deduced that the cis configuration on the j3-ionone ring of
a-carotene makes it a better antioxidant compared with 13-
carotene. Sir, since my return to Nigeria in 1996, our
Laboratory has remained a consulting and collaborative
centre for colleagues in various Departments in the
University and outside for antioxidant research activities.
Thus, with Professor J.O. Moody of Pharmacognosy
Department and his first PhD student Dr. Yemisi Ogundipe,
we reported the antioxidant activities of extracts of Mallotus
oppositifolium in model systems (Farombi et al. 2001).
Again, with the same group and two of my MSc students we
reported for the first time, using the ferric thiocyanate
method, horseradish peroxidase catalyzed reactions and ~-
carotene linoleate model system the antioxidant activities of
the leaf and root extracts of Alchomea laxiflora, a plant used
locally for the preservation of food items in Nigeria. Thus,
qualifying the use of the leaves in the food industry for
preservation of lipid food products, which are prone to
rancidity and oxidation (Farombi et al. 2003).
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UNIVERSITY OF IBADAN LIBRARY
a -Carotene
~. Carotene
110
Lutein
HO
Zeaxanthin
Fig. 15: Structures of carotenoids. Source: Farombi and Britton 1999.
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400
!350 i..•.•Control (AWN) i
1 i~~el19 il3C~4 ':~:nIi..•. ~ene !
,,200 l...A•l.IN.: Tooop!IeJOl J'5.
iGo 150
!
f 100
50
~ ~ 00 rn ~ ~
Timt(mill)
Fig. 16: Effect of carotenoids and alpha-tocopherol on AMVN-induced
phopspholipid hydroperoxide formation. The points represent the
means of four experiments. Source: Farombi and Britton 1999a.
Bioprospecting for novel natural antioxidants in medicinal
plants and vegetables that may be relevant in pathologies
involving ROS as well as preservation of food substances in
food industries, together with one of my former PhD students
Dr. Akinmoladun who is now a Senior Lecturer in Federal
University of Technology (FUTA) Akure, we screened 10
selected plants used traditionally for various ailments-for
antioxidant and radical scavenging properties-using seven
different methods and assays involving ROS. We reported
that the methanol extracts of the studied plant parts possess
significant antioxidant and radical scavenging activities due
to the phytochemical contents of the plants and as such make
them potential candidates as natural chemoprophylactic
agents (Akinmoladun et al. 201Oa). Subsequently, we
considered and reported in isoproterenol treated rat model the
cardioprotective properties of one of the promising plants,
Spondias mombin, used traditionally in the management of
diabetes mellitus, the treatment of psychiatric disorders and to
gain and retain good memory (Akinmoladun et al. 201Ob).
Also, we reported the antioxidant and radical scavenging
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UNIVERSITY OF IBADAN LIBRARY
properties of Hibiscus sabdariffa L (Malvaceae) used in
making 'Sobo', a local popular drink in Nigeria. It is shown
to lower both the systolic and diastolic blood pressures in
patients presenting with essential hypertension (Herrera-
Arellano et al. 2004).
Further, we demonstrated its antigenotoxic properties in
bone marrow micronuclei assay (Farombi and Fakoya 2005).
I must point out that in recommending a dietary substance or
any plant-based phytochemical as a potential antioxidant, it is
necessary to establish its antioxidant and/or pro-oxidant
properties in vivo, as well as its general safety because pro-
oxidant effects of fruits and vegetable products have been
observed repeatedly in humans (Young et al. 2002).
In collaboration with Dr. Lars Dragsted of Institute of
Food Safety and Toxicology, Soborg, Denmark, we demon-
strated both anti and pro-oxidant properties of Bowman-Birk
inhibitor (BBI), a well characterized soy-derived 8 kDa
protease inhibitor (Farombi et al. 2004). Using protein
oxidation biomarkers as indices of biological protection
afforded by dietary antioxidants, we demonstrated pro-
oxidant effects of BBI protease inhibitor at high dose as
reflected by marked increase in plasma protein oxidation
biomarkers whereas half the dose was not able to elicit this
(pro-oxidant) effect and even acted as an antioxidant in
support of antioxidant properties of BBI.
This study shows that a plant-based phytochemical or
nutraceutical can act as both antioxidant (especially at low
dose) and/or pro-oxidant (at high dose) thus drawing caution
on the use of antioxidative agents generally. So in the words
of Paracelus, the father of Toxicology, the dose determines
toxicity. Our modest contributions on Kolaviron from
Garcinia kola as antioxidant will be considered later in this
lecture. Mr. Vice-Chancellor Sir, I am happy to report that
my contributions on Free Radical Chemistry and novel plant-
based phytochemicals as antioxidants led to the award and
my induction as Fellow of the Royal Society of Chemistry
(FRSC) of the United Kingdom in 2010 and this was cited
and published in the popular British newspaper "The Times".
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UNIVERSITY OF IBADAN LIBRARY
Chemoprevention with Selected Chemopreventives
Convincing and compelling evidences arising from both
preclinical and clinical investigations indicate that plant-
based diet rich in a wide variety of fruits and vegetables are
effective in preventing or reversing health-threatening
diseases including cancer. Thus, search for novel chemo-
preventive agents, acting on specific and/or multiple
molecular and cellular targets, holds promise as a rational
strategy to the control of these diseases. In the last 20 years, I
have chosen to work in-depth on some selected chemo-
preventives, understanding their pharmacological
mechanisms of actions -at the cellular and molecular levels.
Collaborating with Dr. Takuji Tanaka of the Department of
Oncologic Pathology, Kanazawa Medical University, Japan,
we examined and reviewed certain chemopreventives
abundantly present in our daily fruits and foods. They are
Auraptene (7-geranyloxycoumarin), a coumarin derivative
obtained from citrus fruits such as grapefruits (Citrus
paradise); Nobiletin, a polymethoxyflavonoid occurring
exclusively in citrus fruits (Citrus depressa); Zerumbone, a
monocyclic sesquiterpene occurring in rhizomes of Zingiber
zerumbet Smith (Zingiberaceae) and l' -Acetoxychavicol
acetate (ACA) present in the seeds and rhizomes of Languas
galangal (Zingiberaceae), used as a ginger substitute, as
stomach medicine and traditional condiment in Thailand and
other countries in Southeast Asia (Farombi and Tanaka
2007). Other selected chemopreventives are Curcumin from
Turmeric, Epivernodalol and its phenolics from Vernonia
amygdalina (bitter leaf), Soybean polyphenols from
Soybeans, Quercetin from onions, 6-Gingerol from Ginger
and our favourite Kolaviron from Garcinia kola (bitter kola).
For the purpose of this lecture I will discuss some of our
findings on the use of some selected chemopreventives
isolated and characterized from these plants in the prevention
and management of diseases.
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UNIVERSITY OF IBADAN LIBRARY
Curcumin
Curcumin is a favourite chemopreventive phytochemical to
many investigators especially in the area of cancer biology
worldwide. It is derived from turmeric. Because of its
brilliant yellow colour, curcumin is used as a food additive,
particularly in making 'curry,
It is used to treat various common ailments including
stomach upset;. flatulence, dysentery, ulcers, jaundice,
arthritis, sprains, wounds, skin and eye infections (Singh
2007). It is an age-old spice with modem target and
relevance. Its use in biliary diseases was documented in 1937
(67 patients treated), its antibacterial action in 1949 and its
ability to decrease blood sugar levels in human subjects (i.e.
its use as an antidiabetic) in 1972 (Aggarwal and Sung 2008).
Our gain in knowledge about curcumin has been exponential
over recent years. For instance, we reported its ability to
attenuate Gentamicin-mediated nephrotoxicity and reverse
phthalate-induced testicular damage via its intrinsic
antioxidant properties (Farombi and Ekor 2006, Farombi et
al. 2007). Several studies have also revealed that curcumin
has antioxidant, antibacterial, antifungal, antiviral, anti-
inflammatory, antiproliferative and pro-apoptotic effects
(Aggarwal et al. 2007).
One of the most well-defined mechanisms underlying
chemopreventive effects of curcumin is suppression of tumor
promotion. My contribution to understanding of the
underlying molecular mechanisms of chernoprevention of
liver toxicity and cancer by curcumin was during my sojourn
in the Laboratory of Molecular Carcinogenesis and Cancer
Chemoprevention, Seoul National University, South Korea
(2005-2006) as a Visiting Professor working with Professor
Young-Joon Surh, the 2006 best Korean Scientist and a pre-
eminent Scholar in Cancer chemoprevention. Actually, I had
dreamt and prayed to work with this man since July 2001
given his profound contribution in the field when I first met
him at the International Conference of the Society for Free
Radical Research in Mauritius. The prayer was answered in
2005 when he invited me on a Ministry of Science and
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UNIVERSITY OF IBADAN LIBRARY
Engineering, Korea Grant. We investigated while in Seoul the
mechanisms by which curcumin elicits hepatoprotective and
other chemopreventive effects in association with' heme
oxygenase-l (HO-l), a stress-responsive enzyme widely
distributed in many mammalian tissues (Farombi and Surh
2006) and the role of a transcription factor Nuclear erythroid
related factor-2 (Nrf2) which plays a pivotal role in the
activation of Antioxidant Response Element (ARE)-driven
antioxidant gene expression (fig. 17). We demonstrated and
documented for the first time that curcumin protects against
Dimethylnitrosamine-induced liver injury through HO-l
expression and activation of Nrf2 signaling (Farombi et a1.
2(08) (figs. 18a and b) in rat liver in vivo. These mechanistic
studies provided clear understanding of the liver
chemopreventive properties of curcumin.
Curcumin
~
1'.::ift~f[Qit;.fl ?
\ ~I-
.L
HEPATOTOXICITY
Fig. 17: Mechanism of hepatoprotection by Curcumin via HO-l mediated
NrF2 activation. Source: Farombi and Surh 2006.
40
UNIVERSITY OF IBADAN LIBRARY
A Curcumin (mglkg) A Cureumln (mgIlg)
o 100 200
Nr12
HO-1
Actin ••••••••
Actin B cell lysate - + + +
cold oIigonucIooUdo +
B curwmin + +140 * ¥
Nrl2{
o 100 200
Curcumln (mglkg)
Fig. 18: (a) Effects of curcumin treatment on HO-l expression (A) and
activity (B) in rat liver. Values are means ± SD (n = 6). *significantly
different from the vehicle control (p < 0.001); (b) Activation of Nrf2
by curcumin in rat liver. (A) Effects of curcurnin on the nuclear levels
of Nrt2. (B) Effect of curcumin (200 mglkg) on the ARE-binding
activity ofNrt2 in rat liver. Source: Farombi et al. 2008
Vernonia amygdalina (Asteraceae)
Vernonia amygdalina, a member of the Asteraceae family is
commonly called "bitter leaf' because of its bitter taste. It is
known as Ewuro in Yoruba, Onugbu in Igbo language, Oriwo
in Bini and Chusar doki in Hausa. The leaves are used as
green leafy vegetables and may be consumed either as a
vegetable (leaves are macerated in soups) or aqueous extracts
used as tonics for the treatment of various illnesses (lgile et
al. 1995). In the wild, chimpanzees have been observed to
ingest the leaves when suffering from parasitic infections
(Huffman and Seifu 1989; Huffman 2003). Traditionally, the
leaf extracts are used in the treatment of varieties of ailments
ranging from emesis, nausea, loss of appetite, dysentery and
other gastrointestinal tract problems to sexually-transmitted
diseases and diabetes mellitus among others (Argheore et al.
1998; Farombi and Owoeye 2011). Some of these and other
uses have been verified experimentally and documented by
various workers, thus providing scientific evidence to support
many of these claimed health benefits (Izevbigie et al. 2004;
Farombi and Owoeye 2011).
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UNIVERSITY OF IBADAN LIBRARY
Mr. Vice-Chancellor Sir, I am happy to report that I have
trained and supervised two PhD candidates who worked on
the chemopreventive aspects of bitter leaf. They are Dr.
Omolola Adesanoye and Dr. Olatunde Owoeye who are both
Senior Lecturers in the Departments of Biochemistry and
Anatomy of this University respectively. We reported the
antioxidant activity of the phenolic-rich fraction of Vernonia
amygdalina using several assays involving ROS (Adesanoye
and Farombi 2014) and the chemoprotective properties of this
fraction in an experimental model of tert-butyl hydroperoxide
(t-BHP)-induced human erythrocyte lysis in vitro (Adesanoye
.et al. 2013). The advantage of this antioxidant property has
been revealed in neurotoxic studies and possible application
in patients receiving radiotherapy for cancer treatment. In this
connection, Owoeye and colleagues reported the neuro-
protection of the cerebellum by the methanolic extract of
Vernonia amygdalina leaves on the gamma-irradiated brain
of Wistar rats (Owoeye et al. 2011). Subsequently, we
demonstrated that Vernonia amygdalina protected against
carbon tetrachloride and 2-acetylaminofluorene-induced liver
injury by mechanisms involving scavenging of reactive free
radicals generated by these carcinogens and induction of
phase 2 drug metabolizing enzymes (Adesanoye and Farombi
2010; Adesanoye et al. 2016). In pursuance of good science
and breaking new grounds in the Vernonia amygdalina story,
a man had to sell his Mercedes Benz to add to the money
raised for him to travel outside of the country in order to carry
out an important aspect of his PhD work. Thus, Owoeye in
collaboration with experts at the Research Institute of
Chemistry, International Center for Chemical and Biological
Sciences, University of Karachi, Pakistan isolated and
characterized a Sesquiterpene lactone compound named
Epivernodalol (C20H2408) for the first time from this
plant using spectroscopic methods (Owoeye et al. 2010). He
subsequently showed that Epivemodalol was active against
skin melanoma cell line (HT-144) demonstrating its potential
anticancer property against human skin cancer (table 1).
Other investigators including my friend and collaborator
Professor Ernest Izevbigie formerly of Jackson State
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University, USA and now Vice-Chancellor of Benson
Idahosa University, Benin City showed that certain fractions
of Vernonia amygdalina inhibited cultured human breast
tumour cells (MCF-7) growth (Izevbigie 2003; Izevbigie et
al. 2004) and acted as DNA-damaging anti-cancer agent
against breast cancer (Yedjou et al. 2008). These studies raise
the potential application of Vernonia amygdalina (bitter leaf)
in the management and possible treatment of human breast
cancer. Happily, certain phytochemicals from bitter leaf have
been formulated into pills now used in the management of
breast cancer.
Table 1: Activity of Vernonia Amygdalina Del. Extract, Fractions,
Epivernodalol and Doxorubicin against HT-144
(skin melanoma) Cell Line
Cod" GIs. (1Ig/mI) TGI (jtglrol) LC5D tllg/roll
MEVA 86± 1.3 14L3± 4.7 199± 10.8
(eztrsct)
VAn 3.3±03** 63±O3** 10.6±0.8**
(fraction)
VAP 9.7±23* 212±S.4* 37.7 ± 4.4*
(fraction)
Epivemodalol 1.76± 03** 733 ±05S*· 22± 1.2**
Doxorubicin 0.01±0 0.Q7± 0.03 0.48±O.l
Each value represents the means ± SD of three independent experiments.
* Significantly different from MEV A (p < 0.05). ** Significantly different
from MEV A (p < 0.01). GI50 = Growth inhibition of 50% of the cells; TGI
= Total growth inhibition. LC50 = Lethal concentration of the
compound/extract that kills 50% of the cells. MEV A: methanolic extract
of Vernonia amygdalina; YAP: petroleum ether fraction; VAD:
dichloromethane fraction. Source: Owoeye et al. 2010.
Soybeans
Flavonoids continue to draw attention as possible, very useful
therapeutic agents for combating pathologic states associated
with free radicals. The role of dietary flavonoids in the
prevention of several chronic diseases has been the subject of
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UNIVERSITY OF IBADAN LIBRARY
intense research interest and the soy phenolics have been the
focus of particular attention. Furthermore, there is increasing
evidence that dietary phytoestrogens present primarily in
soybeans as isoflavones have a beneficial role in chronic
renal disease (Ranich et al. 2001). Nutritional intervention
studies have shown that consumption of soy-based diet owing
to intrinsic polyphenolic antioxidants (Ekor 2009) reduces
proteinuria and attenuates renal functional or structural
damage in animals and humans with various forms of chronic
renal disease (Ranich et al. 2001).
Our search revealed that the clinical use of Gentamicin,
one of the most important aminoglycoside antibiotics used
widely for the treatment of serious and life-threatening
infections is limited by its nephrotoxicity (Mingeot-Leclercq
and Tulkens 1999). In this connection, we investigated and
reported the protective effect of phenolic-rich fraction of
soybean in a rat model of gentamicin-mediated kidney
damage (Ekor et al. 2006). This effect was ascribed to the
rich antioxidant polyphenolic content of the soybean. In
continuation of enhancing the therapeutic indices of clinical
drugs with undesirable side effects, we therefore
hypothesized that the antioxidant polyphenolic compounds in
soybean with demonstrable anti-tumor activity (Barnes et al.
1990) may provide the protective benefit in cisplatin-
mediated nephrotoxicity. We expressed the optimism that the
anticarcinogenic effect of soybean may synergize with that of
cisplatin while at the same time protecting the kidney from
damage by the latter. This would enhance the therapeutic
efficacy and clinical utility of cisplatin. We reported that the
polyphenol-rich fraction of soybean via antioxidant and anti-
inflammatory actions offered protective benefit against
cisplatin-mediated acute toxic injury to the kidney (fig. 19)
(Ekor et al. 2010).
These findings have implications in translational medicine
and clinical applications in patients receiving amino-
gylcosides and chemotherapeutic drugs like cisplatin. Mr.
Vice-Chancellor Sir, the PhD thesis that emanated from
this novel and translational science was adjudged to be
the best PhD thesis in Basic Medical Sciences in Nigeria
Universities by NUC in the year 2009.
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UNIVERSITY OF IBADAN LIBRARY
40
35
o Creatinine (JU110)
30 ill BUN
25 ~'
f6 -{"S.
'
20
8•• 15
10
5
0
Control COOP COOP+ COOP+ COOP. PESB
(2mg1kg) PESS PESB PESB (1.0glkg)
(0.25g1kg) (O.Sglkg) (1.0glkg)
Fig. 19: Effect of the phenolic extract of soybean (PESB) on serum
creatinine (CREA) and blood urea nitrogen (BUN) of normal and
cisplatin (CDDP)-treated rats. *p < 0.001 when compared with
control. **p < 0.05 and ***p < 0.001 when compared with CDDP
group. Source: Ekor et al. 2010
Ginger (Zingiber officinale Roscoe, Zingiberacae)
Ginger (Zingiber officinale Roscoe, Zingiberacae), another
interesting chemopreventive spice is a medicinal plant that
has been widely used all over the world, since antiquity, for a
wide array of unrelated ailments that include arthritis,
rheumatism, sprains, muscular aches, pains, sore throats,
cramps, constipation, indigestion, vomiting, hypertension;
dementia, fever, infectious diseases and diabetes (Awang
1992; Wang and Wang 2005). The pungent principles of
ginger include gingerols, shogaols, paradols, and zingerone
(Surh et al. 1999). These pungent phenolics of ginger possess
antioxidant, anti-inflammatory and anticarcinogenic
activities.
Currently, there is a renewed interest in ginger, and
several scientific investigations have been initiated aimed at
isolation and identification of active constituents of ginger,
scientific verification of its pharmacological actions and of its
constituents, and verification of the basis of the use of ginger
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UNIVERSITY OF IBADAN LIBRARY
in some of several diseases and conditions. Our interest is in
6-Gingerol, a major pungent principle in gingerol owing to its
strong anti-inflammatory and antioxidant properties and the
role of these activities in various diseases. Thus, we examined
6-gingerol from ginger in inflammation-associated colitis and
colon cancer. One of my PhD students, Mr. Jide Ajayi took
on the arduous task of extracting, isolating and characterizing
6-gingerol from ginger, a feat we initially considered
impossible given our limited facilities but he worked so hard
and today, we have established in my laboratory a simple
procedure for characterizing this compound from first
principle. Figure 20 depicts the HPLC chromatogram of 6-
gingerol isolated from ginger.
I_ !~1mlS-1l1E(); (~).=~14OOB1v4
~. »0,"", .",*,,,,,,,,,,,,.,,:;;:C:;:::,,,,,,, ... ·_-";~,W.'.',W»>'==»"",>'""·'
431 469-
3lJ 341-
[ ~
.s eoc• J9J c: m-
.Q .Q
!l '".. .~.Q .Q.
71 84-
.4lJ--t-----'------.--------.1 .44--t---L-------. --------.
1 1
OO:{lO 04:00 08:00 00:00 06:00 n:ol
Tim, [••• :,,] Ti••• [•••• :••]
Fig. 20: HPLC chromatogram of isolated 6-gingerol from rhizomes of
Zingiber officinale (A). HPLC chromatogram of standard 6-gingerol
(B). This figure is available in colour online at wileyonlinelibrary.
com/journal/ptr. Source: Ajayi et al. 2015.
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UNIVERSITY OF IBADAN LIBRARY
Using Dextran sulphate sodium-induced colitis
experimental model known to mimic the pathological features
of human colitis, we showed that 6-Gingerol suppressed the
induction of colonic oxidative damage and circulating
concentrations of pro-inflammatory cytokines in mice
(table 2) as well as preneoplastic lesion in distal colon of
mice (fig. 21) (Ajayi et al. 2015). Furthermore, in our chronic
ulcerative colitis model, using sulfasalazine (anti-colitis drug)
as positive control, 6-gingerol reversed the clinical features of
chronic colitis ranging from diarrhea, shortening of the colon
to rectal bleeding. Using immunohistochemical technique, we
further showed that 6-gingerol attenuated markers of
oxidative and nitrosative stress and abrogated a panel of pro-
inflammatory genes and certain transcription factors
expressed in chronic ulcerative colitis. Our preliminary data
shows. its effect on colon cancer and experiments are ongoing
in my laboratory to establish the veracity of this claim. In
totality, these studies qualify 6-gingerol as anti-colitis drug
and a lead compound in the possible management of human
colon cancer.
Table 2: Effects of 6-gingerol on Levels of Interleukin-Ijl, Tumor
Necrosis Factor Alpha, Nitric Oxide Concentration, and
. Myeloperoxidase Activity in DSS-exposed Mice
Control 6·GRalone DSSalone DSS "6·GR1 DSSt6-GR2 DSS+6-GR3
1l·1~ 91.21±4.06 90.32±5.08 118.7±4.21' 92.57±4.08b 91.14±5.0a" 88.89±4.W'
Ttfll 19.24±2.51 19.46f2.27 34.71 ±2.25' 18.84± 2.07b 19.6±2.07b 21.H2.0'f
NO 2.32±O.25 2.36tO.28 3.78±O.23' 2.4B±O.45b 2.40±O.3gl> 2.45tO.2t
MPO 1.4!hO.16 1.45iO.35 2.11:0.21' 1.52±O.34b 1.46±O.3i' 1.51iO.2'f
IL-IP, interleukin-If (pg/ml.); TNF-a, tumor necrosis factor alpha
(pglrnL); NO, nitric oxide (units/mg protein); MPO, myeloperoxidase
(units/mg protein); DSS, dextran sulphate sodium. 6-GRl, 6-GR2, and 6-
GR3 denote 50, 100, and 200 mglkg of 6-gingerol, respectively. Each bar
represents mean ± SD of seven mice. 'Values differ significantly from
control (p<0.05). bValues differ significantly from DSS group (p<0.05).
Source: Ajayi et al. 2015.
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UNIVERSITY OF IBADAN LIBRARY
Fig. 21: Effects of 6-gingerol on DSS-induced preneoplastic lesion in
. mice distal colon. Control and 6-gingerol alone (6-GR) showing
normal architecture without suspicious focus. Colons of mice treated
with DSS alone have enlarged ulceration with several aberrant crypt
foci. Dextran sulphate sodium-treated mice administered with 6-
gingerol at 50 mg/kg (6-GRl) and 100 mg/kg (6-GR2) showing
normal architecture. Dextran sulphate sodium mice administered with
6-gingerol at 200 mg/kg (6-GR3) showing normal histological
structure but with mild ulceration and a very few aberrant foci (red
arrow). Original magnification of 160X. Source: Ajayi et al. 2015.
Garcinia kola Heckel (Guttiferae)
Another interesting chemopeventive and our favourite in
Biochemistry Department is Garcinia kola, a tropical
flowering plant found in western and central Africa, which
produces large, orange fruits and brown, nut-like seeds
embedded in an orange-coloured pulp. It is popularly known
as bitter kola because of its bitter taste. It is called various
names in different parts of Nigeria: Orogbo (Yoruba), Edun
(Edo), Namiji ngooro (Hausa), aku ilu, ugugolu (Igbo). Bitter
kola plays pivotal role in traditional hospitality and
ceremony. For instance bitter kola and other components like
sugar cane, kolanut and honey are usually presented during
naming ceremony of babies and the officiating elder uses the
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seed to pray for the child, with the believe that properties of
longevity and pleasant living will be conferred on the baby.
The elders after chewing the seed pray thus "Orogbo 1'0 ni
kio gbo, obi nii bi ibi danu, nire nire laa soro ataare, ladun-
ladun la aba ile oniyo, adun ni toyin, adun ni tireke"
meaning bitter kola (orogbo) says you should grow to old
age, kolanut (Obi) wards away evil, table salt (lyo) is always
found with sweetness, honey is renowned for sweetness,
sugar cane is renowned for sweetness too.
Apart from the cultural use of bitter kola, it plays a very
important role in African ethno-medicine. The seed is
employed as a general tonic, and is believed to ' cure
impotence. Traditionally, the seeds are used in the treatment
of inflammatory disorders and liver disease. For instance,
extracts of the seeds led to remarkable improvement of liver
function in patients with chronic hepatitis and cholangitis
after treatment for ·14 days at a Nigerian herbal home (Iwu
1982). The seeds are used medicinally to treat parasitic,
microbial, and viral infections as well as treatment of
bronchitis, throat infections, chest colds, and coughs. Some of
these claims have been verified by experimental findings. For
instance Mr. Ifeoluwa Awogbindin, one of my PhD students,
under the mentoring of myself and Professor David Olaleye
of our Virology Department, demonstrated that bioflavonoid
fraction from Garcinia kola protected BALB/c mice against
influenza AlPerth/H3N2/16/09 (PrIH3N2) virus infection
(Awogbindin, Olaleye and Farombi 2015). This study
indicates that this fraction is effective for delaying the
development of clinical symptoms of influenza virus through
a mechanism unrelated to those deployed by the existing anti-
influenza drugs but closely associated to its antioxidant and
immunomodulatory properties.
Phytochemical studies on Garcinia kola revealed the
presence of complex mixtures of phenolic compound triter-
penes and benzophenones. Subsequently, Kolaviron
(biflavonoid complex containing GB 1, GB2 and kola-
flavanone), a deffated fraction of alcoholic extract of
Garcinia kola seeds was isolated (Iwu 1985) (fig. 22). Other
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UNIVERSITY OF IBADAN LIBRARY
researchers have isolated some other compounds from bitter
kola. For example, one of my PhD students Dr. Ademola
Oyagbemi, while collaborating with-my friend late Professor
Johan Esteryhyse of the Cape Peninsular University of
Technology, .Cape Town South Africa- isolated and
characterized for the first time Squalene, a novel antioxidant,
anticancer and cholesterol lowering phytochemical and
Rugulosin which has antibiotic and antimycotic properties
and acts asmv-1 i-ntegraseinhibitor.
Mr. Vice-Chancellor, our interest in Garcinia kola
research, especially the characterized bioflavonoid termed
Kolaviron, dates back to ·23 years in Biochemistry
Department. The interest in the research was facilitated by my
mentor and PhD Supervisor, Professor Godwin Emerole.
Today, we have graduated over 50 MSc students, 6 PhD
students and currently another PhD student is on the project.
Under the training of Professor Emerole and my humble self,
Dr. O.A. Adaramoye whose promotion to the grade of Reader
was announced a few days ago, was the first PhD student on
Garcinia kola. We have also collaborated with world experts
on chemoprevention on the project in countries spanning 4
continents of the world. In other words, we have taken
research on this wonderful seed beyond the shores of this
country. Our systematic and mechanistic experimental
findings at the cellular and molecular levels have lent
credence to the therapeutic value of this seed earlier alluded
to by traditional elders. Although some do not know the value
of this seed and therefore it has remained untapped as a novel
chemopreventive and therapeutic agent, just like the Nigerian
Juju musician, King Sunny Ade in 1973 released a musical
album on this seed and said "Ki Ian fani Orogbo, Kilan fani
Orogbo, Ohun ta pa ti 0 lawe, eyi ta je to tun koro, Kilan fani
Orogbo----". It was later in 1977, I guess elders who
understood the real value of bitter kola corrected him and he
released another album and sang thus: "Mojorogbo, Kiohun
mi le gbo, mo jogede, ki ohun mi le de, mo je kukundu ku
olohun areree=",
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UNIVERSITY OF IBADAN LIBRARY
RI R2 R3 R4
GBI OH H OH H
GBl OH H. OH OH
Kolanavanone OH H OCH, OR
KOLAVIRON FROM GARCINIA KOLA
Fig. 22: Garcinia kola and isolated bioflavonoid termed Kolaviron.
I shall now summarize some of our humble contributions
to knowledge on Garcinia kola and its isolated bioflavonoid,
Kolaviron, as novel chemopreventive agent.
Kolaviron as Liver Chemopreventive Agent
Garcinia kola seeds and seed extracts have been shown to be
of benefit to human health, and relevant in the management
and chemoprevention of life-threatening diseases. The effects
range from antidiabetic, immunomodulatory, antiviral, anti-
inflammatory, and antioxidant activities to strong
hepatoprotective properties. Kolaviron and other isolates of
Garcinia kola seeds were shown to protect against CCI4-
induced liver injury, reduce significantly CCl4-induced
increases in serum aminotransferases and sorbitol dehydro-
genases, and protect against CCl4-mediated liver damage by
modulating the cholesterol:phospholipid ratio as well as the
toxic onslaught imposed on liver microsomal marker
enzymes (Farombi 2000). Kolaviron given orally to rats prior
to challenge with 2-acetylaminofluorene reversed its effects
on ornithine carbamyltransferase and other biochemical
indices of hepatic damage (Farombi et al. 2000). The
protective effect of kolaviron was comparable to the effect of
butylated hydroxylanisole, indicating that kolaviron may act
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UNIVERSITY OF IBADAN LIBRARY
as chain-breaking in vivo antioxidant. Furthermore, purified
fractions from Garcinia kola elicited hepatoprotective
properties in the same model of CCLJ-mediatedliver damage
(Adaramoye et al. 2008).
Of particular interest is the remarkable effect 'Ofkolaviron
on Aflatoxin Bt (AFB.)-induced liver damage. AFBr- a
potent hepatotoxic and hepatocarcinogenic agent, is produced
by the mould Aspergillus flavus, which contaminates cereal
grains and nuts in tropical regions of the world such. as
Nigeria. AFB. and hepatitis B have been implicated in the
aetiology of hepatocellular carcinoma, which has one of the
poorest 5-year survival rates (Groopman et al, 1992) and
accounts for 15% of total cancer mortality. We demonstrated
the chemopreventive effect of kolaviron against the hepatic
oxidative damage (fig. 23) and genotoxicity (fig. 24) induced
by APR. in rats (Farombi et al. 2(05) by mechanisms
involving induction of phase 2 xenobiotic metabolizing
enzymes capable of detoxifying toxic aflatoxin metabolites.
We showed also that Kolaviron protected against Dimethyl
nitrosamine (DMN)-mediated liver toxicity and histological
changes in rats (fig. 25) (Farombi et al. 20(9).
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UNIVERSITY OF IBADAN LIBRARY
60r • 17 -:s 1400S * •
6 e~1200 ~ I:twtl
r1000
"C
!800
·'.;6600
:!v 400
~
::9v 2000 -
0
CTRl KV
Fig. 23: Effects of kolaviron, vitamins C and E on (A) the activities of serum alanine aminotransferase (ALT), aspartate
aminotransferase (AST) and gamma glutamyltransferase (y-GT), (B) malondialdehyde (MDA) and lipid hydroperoxide
(LHP) of rats treated with aflatoxin B. (AFB.). *P<O.OOIsignificantly different from control; values are mean±SD for
five rats in each group. **P<O.Ol significantly different from AFB. group; ***P<O.05 significantly different from
AFB. group. Source: Farombi er al. 2005.
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UNIVERSITY OF IBADAN LIBRARY
3.5
3 J Ie: CTRL *
Q KV I
sa VitC
2..5 DID VitE
91 AFBl
~ 2 Ell AFB1+KV
~ AFB1+VitC
~0.. 1.5 11II AFB1+VitE
z:::i •
1
0.5
o I I' ,IX'lr'I, ~ ,
CTRL KV VitC VitE AFB1 AFB1AFB1 AFB1
+KV +VitC +VitE
Fig. 24: Effects of pretreatment with kolaviron, vitamins C and E on the frequency of occurrence of micronucleated
polychromatic erythrocytes (MNPCEs) in rats treated with aflatoxin B. (AFB.). Values are mean ± SD for five rats in
each group. *P<O,OOI significantly different from control; **P<O.Ol significantly different from AFB. group. Source:
Farombi et al. 2005.
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UNIVERSITY OF IBADAN LIBRARY
Fig. 25: Effects of kolaviron and curcumin on DMN-induced histological changes in the livers of rats. (A) Liver from a
vehicle treated rat. (B) DMN-treated rat liver. (Cj-liver from the rat treated with kolaviron (100 mg/kg) plus DMN. (D)
liver from a rat treated with kolaviron (200 mg/kg) and DMN. (E) liver from a rat treated with curcumin (200 mg/kg)
and DMN. Liver sections were stained with hematoxylin and eosin. X400. Source: Farombi et al. 2009.
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UNIVERSITY OF IBADAN LIBRARY
Biochemical Basis for the Chemopreventive Action of
Kolaviron
Earlier hypotheses regarding the biochemical mechanisms of
the hepatoprotective effect of kolaviron stated that it
protected against carcinogen-induced liver injury by
stabilizing the membrane, and by interfering with the
distortion of the cellular ionic environment associated with
xenobiotic treatment; also possibly by the interference of
kolaviron with hepatic drug metabolism (Braide 1991). These
studies, however, did not elucidate the hepatoprotective
mechanism of action of kolaviron.
Kolaviron modulates Xenobiotic Metabolizing Enzyme
Complex System
We investigated the hepatoprotective action of kolaviron
using CCl4 as a model compound. Our data showed that
kolaviron treated with CCl4 in rats preserved the activities of
certain phase 1 enzymes, especially aniline hydroxylase, a
representative CYP 2El enzyme (Farombi 2000), while
administration of kolaviron alone did not alter the activity of
these enzymes. This result was further corroborated by our
recent observation that kolaviron did not influence the
constitutive expression of CYP 2El, determined by western
blot. Our results further showed that treatment of rats with
kolaviron resulted in a marked elevation in the activity of
major phase 2 conjugation enzymes (Farombi 2000; Farombi
et al. 2005) (fig. 26), demonstrating that kolaviron protects
against carcinogen-induced damage to tissues by stimulating
the activities of phase 2 enzymes to detoxify toxic reactive
metabolites generated by the carcinogens.
Following CCl4 administration to rats, the
cholesterol:phospholipid ratio was increased, suggesting a
decrease in membrane fluidity with a resultant alteration in
membrane function (Farombi 2000). Co-administration of
kolaviron with CCl4 reversed the CCl4-induced elevation in
the cholesterol:phospholipid ratio and preserved some
microsomal marker enzymes, suggesting that kolaviron may
protect biomembranes against damage, maintain membrane
fluidity (Farombi 2000), and stabilize the drug metabolizing
enzyme complex.
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UNIVERSITY OF IBADAN LIBRARY
UDPGT
a 300 •• F'=NOO 2500r-GST250 .. •• ~2000 12
§! )200 1, •••
~~ II. L .. *i* r1500 ;§2.a-~~150 .* ~
:~ :€ ~ 1000 S
~!i - 1!00 V l- I~ "~ i--~ *'" .'".' .*. f
tfj 50 * 500 ~~
CJ
o I I i I I
CTRl KV vac oVItE AFB1 AFB1 AF131AFB1
+KV +VitC+VitE
Fig. 26: Effects of kolaviron, vitamins C and E on the activities of uridyl
glucuronosyltransferase (UDP-GT), NADH:quinone oxidoreductase
(NQO) and glutathione S-transferase (GST) of rats treated with
aflatoxin B, (AFBd. Values are mean±SD for five rats in each group.
*P<O.OOI significantly different frOID control; **P<O.Ol significantly
different from AFBI group; ***P<O.05 significantly different from
AFBl group. Source: Farombi et al. 2005.
Kolaviron as a Potent Antioxidant and Free Radical
Scavenger
One of the mechanisms of chemoprevention is the anti-
oxidative activity of chemopreventive agents; thus, the ability
of natural compounds to reverse or mitigate carcinogen-
induced tissue damage may be related to their intrinsic
antioxidant properties.
Using several in vitro chemical models involving the
generation of reactive oxygen species, we evaluated the
antioxidant properties of kolaviron. Kolaviron showed
significant reducing power, and a dose-dependent inhibition
of oxidation of linoleic acid (Farombi et al. 2002). In our
model system, Kolaviron inhibited H202, and was more
effective than butylated hydroxyanisole and ~-carotene, but
comparable in activity with a-tocopherol, a radical chain-
breaking antioxidant. Kolavironalso significantly scavenged
superoxides generated by phenazine methosulfate and
NADH. Furthermore, kolaviron scavenged hydroxyl radicals
by inhibition of the oxidation of deoxyribose. The ability of
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UNIVERSITY OF IBADAN LIBRARY
kolaviron to scavenge hydroxyl radicals by inhibiting the
oxidation of deoxyribose may relate directly to prevention of
the propagation of the process of lipid peroxidation, and may
account for its hepatoprotective properties in vivo (Farombi
2000; Farombi et al. 2000).
Kolaviron Compromises Radical-induced DNA Damage
In human-derived liver HepGZ cells with morphological
characteristics of liver parenchyma cells, kolaviron dose-
dependently inhibited the intracellular ROS induced by H202
(Nwankwo et al. 2000). Using single cell gel electrophoresis
("Comet assay") in collaboration with Professor Steffen Loft
of Panum Institute, University of Copenhagen, we showed
that kolaviron concentration-dependently decreased H202-
induced DNA strand breaks, and oxidized purine and
pyrimidine bases in both human lymphocytes and rat liver
cells (table 3) (Farombi et al. 2004). These data show that
kolaviron is effective against oxidative modification of DNA
and supports the role of kolaviron as an antioxidant, and a
candidate for the chemoprevention of chemically-induced
DNA damage.
Table 3: Effect of Kolaviron on H202-induced Oxidized DNA bases
in Human Lymphocytes
DNASB ENDOIII sites FPGsiies
Tterimelli ('Ie ortail DNA) (';.({tailDNA) rl. ({(ail DNA)
DMS(} 8.ot4.! 2.3±4.6 1.7±2.8
HP! 82.1±6.2 16.7±3.2 17.8±3.4
Kolam (30)IDK'IiL) 7.8±1\ Hi3.7 1.9± 2.5
Kolaviron (30IUJIOI!L+) H:O: 581H1' IO.hU' 9.1±l6'
Kolaviron (60 )IDK'I1L 81H2 15±2.7 1.9±2.4
Kolaviron (60 ~moL'l t·H~O: 47.1±5.2" 6.2±3.8" 5.6±l7"
Kolaviron (90 ~moljlj 7.2±4.7 2.0±2.5 1.5±2's
Kolaviron (90 ~olili + H~ 28.1±3.6" 5.4±3.0" 0±3.1"
Percentage of tail DNA (FPG) and ENDO III sites. FPG=
formamidopyrimidine glycosylase; ENDO III= endonuclease III enzyme;
DNASB- DNA strand breaks. Values are mean ± SD of 5 determinations.
*p< 0.05; **p< 0.01, refers to difference between H202 (lOOumollL)v
treated lymphocytes preincubated with or without kolaviron. Source:
Farombi et al. 2004.
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UNIVERSITY OF IBADAN LIBRARY
Kolaviron Decreases LDL Oxidation and Affects
Biomarkers of Oxidative Stress
Oxidation of low density lipoprotein (LDL) is generally
believed to promote atherosclerosis primarily by leading to an
increased uptake of oxidized LDL (ox-LDL) by macrophages,
and subsequent foam-cell formation. Therefore, attempting to
inhibit or reduce the process of LDL oxidation by anti-
oxidants, which may slow the progression of atherosclerosis,
appears to be a rational and pragmatic approach to preventing
cardiovascular diseases. Thus, in rats treated with kolaviron
for 7 days, lipoprotein resistance to copper-induced oxidation
was highly improved, as shown by a significant increase in
lag time, and a decrease in the area under the curve (AVC)
and the slope of propagation (Farombi & Nwaokeafor 2005).
Markers of lipid oxidation significantly decreased in the
kolaviron-treated rats, with an attendant significant increase
in the total antioxidant activity compared to control.
Additionally, kolaviron inhibited the Cu2+ -induced
oxidation of rat serum lipoprotein in a concentration-
dependent manner, and elicited a significant chelating effect
on Fe2+. Furthermore, kolaviron effectively prevented
microsomal lipid peroxidation induced by iron/ascorbate in a
concentration-dependent manner (Farombi & Nwaokeafor
2005). In totality, the results demonstrate that kolaviron
protected against the oxidation of lipoprotein by mechanisms
involving metal chelation and antioxidant activity, and, as
such, might be of importance in relation to the development
of atherosclerosis and cardiac dysfunction as reported in
similar works (Adaramoye et al. 2005; Adaramoye & LawaI
2015).
Molecular Mechanisms Underlying Chemopreventive
Action of Kolaviron
Kolaviron Compromises Stress Response and Inflammatory
Proteins
The role of inflammation in carcinogenesis has been
extensively investigated and well documented. Many bio-
chemical processes that are altered during chronic
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UNIVERSITY OF IBADAN LIBRARY
inflammation have been implicated in tumorigenesis. These
include shifting cellular redox balance toward oxidative
stress; induction of genomic instability; increased DNA
damage; stimulation of cell proliferation, metastasis, and
angiogenesis; deregulation of cellular epigenetic control of
gene expression; and inappropriate epithelial-to-mesenchymal
transition. Thus, inadequate resolution of inflammation and
uncontrolled inflammatory reactions can evoke a state of
chronic inflammation, which is a common etiologic factor for
various human ailments including cancer (BalkwiII et al.
2005; Aggarwal et al. 2006). Using DSS-induced colitis
(gastrointestinal inflammatory disorder) in rats, we showed
that Kolaviron suppressed the DSS-mediated increase in
colonic nitric oxide concentration and myeloperoxidase
activity, and significantly prevented the increase in
inflammatory mediators, interleukin-If and tumour necrosis
factor alpha in the colon of DSS-treated rats (fig. 27)
(Farombi et al. 2013). Professor S.B. Olaleye of Physiology
Department, another lover of Garcinia kolalKolaviron
research, demonstrated that both crude extracts of G. kola and
kolaviron have the capacity to attenuate gastrointestinal
inflammatory disorders (Olaleye et al. 2000; Olaleye et al.
2010).
Recently one of my proteges, Dr. Abarikwu demonstrated
further the anti-inflammatory property of kolaviron via
inhibition of interleukin-6 (IL-6) secretion in lipopoly-
saccharide stimulation of macrophages (Abarikwu 2014).
Like other early-response gene products, Cycloxygenase-2
(COX-2) can be induced rapidly and transiently by pro-
inflammatory mediators, endotoxins as well as carcinogens
(Kim et al. 2005). Inducible nitric oxide synthase (iNOS) is
another inducible enzyme that causes the overproduction of
nitric oxide during inflammation and tumor development
(Aggarwal and Shishoda 2004; Chung et aI. 2007). Therefore,
suppression of the induction and activity of COX-2 and/or
iNOS has been considered a new paradigm in cancer
chemoprevention in several organs (Chung et al. 2007;
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UNIVERSITY OF IBADAN LIBRARY
Neergheen et al. 2010). Collaborating with Professor Young-
Joon Surh while in Korea, our findings on the molecular
mechanisms underlying hepatoprotective action of kolaviron
indicate that it can suppress certain pro-inflammatory genes
who-se expression have been shown to be regulated by
transcription factors. We demonstrated that kolaviron
abolished the expression of COX-2 and iNOS proteins in
dimethylnitrosamine (DMN)-treated rat liver (fig. 28) and
confirmed by immuno-histochemical staining (fig. 29),
suggesting that kolaviron may be important not only in
alleviating liver inflammation but probably for the prevention
of liver cancer (Farombi et al. 2009). These data suggest that
kolaviron compromises inflammation and oxidative stress (as
reported before) which are "co-conspirators" in the science of
the "killers" and as such is a strong anti-inflammatory
chemopreventive relevant in the management of
inflammation-associated diseases.
_COIliroi
22 • E3 KV
• Control 11II sz
20
SKV
11
IIII!IISZ ~_~~+KDVSS~+' SZ
c:::J DSS
m DSS+KV b b b b
_ DSS+SZ
NO MPO lllF·A1pha Il1Beta
Fig. 27: Effects of kolaviron and sulfasalazine on (A) nitric oxide
concentration and myeloperoxidase activity; (B) tumour necrosis
factor-alpha (TNF-a) and interleukin-I P (IL-l P) levels in colons of
DSS-exposed rats. Each bar represents mean ± S.D. of 6 rats. "Values
differ significantly from control (p<0.05). bYalues differ significantly
from DSS group (p<0.05). DSS, Dextran Sulphate Sodium; KY,
Kolaviron; SZ, Sulfasalazine. Source: Farombi et al. 2013.
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A B
CCM + CCM +
KV - KV
DMN
COX-21::--:
-- :...+.:.;.:-: + ~+ + DMN +;-1 ---+ +iNOS
* >- 70
~:E *60
** ** ~i 50 ** ***~ ~ 40·
~:i .~a3020
0"i 10
~- 0
Fig. 28: Inhibitory effect of kolaviron and curcumin on DMN-induced
COX-2 expression in rat liver. Quantifications of COX-2 (A) and
iNOS (B) immunoblots were normalized to that of actin followed by
statistical analysis of relative image density in comparison to control.
Lane 1, control; lane 2, DMN-treated; lane 3, kolaviron (100 mg/kg)
plus DMN; lane 4, kolaviron (200 mg/kg) plus DMN, lane 5,
curcumin (200 mg/kg) plus DMN. (*P<O.OOI compared with lane 1;
**P<O.05 compared with lane 2; ***P<O.OI compared with lane 2.
Source: Farombi et al. 2009.
Fig. 29: Immunohistochemistry of COX-2 in the liver of kolaviron and
curcumin-treated rats. Treated rat livers were used for immuno-
histochemical analysis of COX-2, using rabbit polyclonal anti-rat
COX-2 antibody as a primary antibody. Positively stained COX-2
staining yielded a brown-colored product. Vehicle treated control rat,
XI00 (A). DMN-treated, XIOO (B); DMN-treated, X400 (C);
kolaviron (l00mg/kg) plus DMN-treated, XIOO (D); kolaviron
(200mg/kg) plus DMN-treated, X 100 (E); curcumin (200 mg/kg) plus
DMN-treated, Xl00 (F). Source: Farombi et al. 2009.
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UNIVERSITY OF IBADAN LIBRARY
Kolaviron Down Regulates Inflammation-Associated
Redox-regulated Transcription Factors
Nuclear factor kappa B (NF-KB) is a ubiquitous transcription
factor that resides in the cytoplasm as a heterodimer
consisting of p50, p65 and IKBa subunits. Upon activation, it
trans-locates to the nucleus where it induces gene
transcription (Nanji et al. 2003). On activation, IKBa
undergoes phosphorylation and ubiquitination-dependent
degradation by 26S proteosomes, thus exposing nuclear
localization signal on p50-p65 heterodimer, leading to its
nuclear translocation. In the nucleus, it binds to a specific
consensus sequence in the DNA (5'-GGGACTITC-3') called
kB binding site. On activation, NF-KB induces expression of
more than 200 genes including COX-2. The transcription
factors NF-KB and AP-l have been reported to be key
regulators of inflammatory protein such as COX-2 and iNOS
(Nanji et al. 2003). Using gel shift Electrophoretic Mobility
Shift Assay (EMS A) and Western blot analysis, we showed
that kolaviron abrogated the DNA binding activity of NF-KB
and AP-l induced by DMN (Farombi et al. 2009) (fig. 30).
Agents that can suppress NF-KB and AP-l have the potential
of preventing the onset of cancer (Aggarwal et al. 2004).
Therefore the inhibition of DMN-mediated DNA binding of
these transcription factors and expression of pro-
inflammatory proteins by kolaviron explains the molecular
basis of the hepatoprotective effect of kolaviron.
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A I B:~E i(;
:zE 0E
00
NF-lCB ---+
AP-1-
!l1 70 60
oL 60 * Ii. *
fz
"" 50
'0450 '00 f 40
~ 30i 30
i 20- l:
20
10 **
**
** **
ti s
~ '0
0 0
Fig. 30: Inhibitory effects of kolaviron and curcumin on DMN-induced
activation of NF-ICB(A) and AP-l (B) in rat liver. Lane 1, free probe;
lane 2, control; lane 3, DMN alone; lane 4, kolaviron (100 mglkg)
plus DMN; lane 5, kolaviron (200 mglkg) plus DMN; lane 6,
curcumin (200 mglkg) plus DMN; lane 7, competitor. *P<O.OOI
compared with lane 2; **P<O.OOlcompared with lane 3. Source:
Farombi et al. 2009.
Kolaviron Abrogates Apoptosis and Related Caspases
In pursuance of additional mechanisms of chemoprevention
with kolaviron, Dr. Adedara my former PhD student, during
his doctorate programme on a John D. and Catherine T.
MacArthur Foundation-funded Fellowship, carried out some
aspects of his research with Professor Premendu Mathur, one
of our collaborators in the Department of Biochemistry &
Molecular Biology, Pondicherry University, India. Dr.
Adedara was able to elucidate other chemopreventive
mechanisms of action of kolaviron in models of testicular cell
death induced by two environmental compounds-Ethylene
glycol monoethyl ether (EQEE) , a widely used industrial
solvent and a component of many cleaning agents, paints and
hydraulic fluid, and Carbendazim (CBZ), a broad-spectrum
and systemic fungicide. Immunoblot analysis revealed
significant increase in stress-inducible protein levels, protein
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expression of active caspases, Fas and Fas-L, accompanied by
elevation of cytosolic cytochrome c level in the testes of
EGEE-treated rats (figs. 31 and 32).
In addition, the observation from immunofluorescence
staining was consistent with the increased apoptotic bodies as
revealed by TUNEL-positive nuclei in the testes of EGEE-
treated rats (Adedara, Mathur and Farombi 20l3c).
Interestingly, carbendazim similarly mediated apoptosis
involving both the mitochondria- and FasL-mediated
pathways (fig. 33) (Adedara, Mathur and Farombi 2013d).
Our results showed that kolaviron not only protected the
testes against damage but also abolished apoptosis in the two
models of testicular death induced by these environmental
toxicants. Thus Kolaviron, may provide additional therapeutic
approach to testicular dysfunction resulting from exposure to
environmental compounds by its anti-apoptotic properties.
2 :1 ••
ciMiii I Cyt C, lll<Da
NFkB,65l<Da
[;;J:Mii,"i:IIII'i;"I-lflI!LI!I:I!!!1 :::::JRi,ih1'1"[]4' 11iiMi!"L, lII_lIlt! A.ctDt,42l<Da
4
_ Lane 1: Control
IIIlIIIIIIIIIII Lane 2:EGEE
_ Lane 3: EGEE + KV1
IIIlIIIIIIIIIII Lane 4: EGEE + KV2
_ Lane S: EGEE + Vit E
o
CylC NFkB
Fig. 31: Effect of kolaviron and vitamin E on cytosolic levels of
cytochrome c release and NF-kB in EGEE-exposed rats. The data are
expressed as mean + S.D.; n=5. *: Values differ significantly from
control (p<O.05). **: Values differ significantly from EGEE (p<O.05).
Source: Adedara et al. 2013c.
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baa 1 2 3 4 5Y' "~ ~ '~~I C...".~.,3"17kD- .•
u '~~~-"'-'ik~"",&~C'l C"'-'P·,.,. ••Y, 37.klh
I
@'t'F' :,,~,e .~ ';,,i4-~1ii;,,~" ;;~ FasL,30klh
Actin, 42 kDa.
5
_ Lane 1: Control
t 'J~-'-"'lJLane 2: EGEE
4 _ Lane 3: EGEE ..•.K. V1
1Lc:':"::J Lane 4: EGEE+KV2Lane~: EGE~Vit E
o
Caspasa 3 caspasa 9 FAS FasL
Fig. 32: Effect of kolaviron and vitamin E on caspases, Fas and FasL in
EGEE-exposed rats. The data are expressed as mean+S.D.; n=5. *:
Values differ significantly from control (p<0.05),. **: Values differ
significantly from EGEE (p<0.05). Source: Adedara et al. 2013c.
50
a
- 40~e....
~ 30
Z
§'",!
E
~ 20...I
Wz
F! 10
b b,c b,c
0
Control CBZ CBZ + KV1 CBZ + KV2CBZ + Vit E
Fig. 33: Testis histopathology guide showing the effect of kolaviron and
vitamin E on seminiferous tubules with TUNEL-positive nuclei in CBZ-
treated rats. Control (A) lOOX, CBZ alone (B) 200%, CBZ + KVl (C)
lOOX, CBZ + KV2 (D) 200X And CBZ + Vitamin E (E) lOOX.
Arrowheads identify TUNEL-positive nuclei. Increased number of
TUNEL-positive nuclei, mainly spermatogonia and spermatocytes, are
seen in testis sections of CBZ-exposed rats. The data are expressed as
mean±S.D. "Values differ significantly from control (p<0.05). hValues
differ significantly from CBZ (p<0.05). "Values differ significantly from
CBZ + KVl (p<0.05). Source: Adedara et al. 2013d.
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UNIVERSITY OF IBADAN LIBRARY
Neuroprotective Mechanisms of Kolaviron-Implications for
Parkinson Disease
We reported for the first time the anti-apoptotic activity of
Kolaviron in PC12 cells, a rat pheochromocytoma, exposed to
endocrine disruptoratrazine. In the PC-12 cells, kolaviron
reversed atrazine-induced generation of reactive oxygen
species detected by Flow cytometric analysis. Furthermore,
kolaviron treatment elicited significant restoration in atrazine-
induced alterations in the expression of apoptosis markers
viz. p53, Bax, Bcl2, caspase-3, caspase-9, cyclooxygenase-2
(COX-2) as well as c-Jun and c-fos (fig. 34) (Abarikwu et al.
20lla). In order to find a possible therapeutic intervention by
application of natural compounds to degenerative diseases,
we selected the SH-SY5Y human neuroblastoma cell line, a
reliable neuronal model system for apoptosis to elucidate the
underlying signal transduction pathway(s) involved in
kolaviron-mediated protection. Thus, we demonstrated for the
first time unequivocally that kolaviron blocked atrazine-
mediated nuclear changes associated with apoptosis (fig. 35);
including nuclear fragmentation, condensation, DNA
laddering (fig. 35), and increased caspase-3 activity.
Interestingly, kolaviron, prevented atrazine-induced changes
in the expressions of p53, Bax, Bcl-2, p21, and mRNA levels
of caspase-3 and caspase-9 (fig. 36) (Abarikwu et al. 2011b).
These data suggest that kolaviron possesses potential
therapeutic properties against chemical-induced apoptotic cell
death in the neuronal system and therefore opens up a new
therapeutic window in progressive neurodegenerative
diseases such as Parkinson's disease. Mr. Vice-Chancellor
Sir, I am happy to report that our new research on preclinical
evaluation of Kolaviron as an anti-parkinsonian lead drug has
been supported by a recently awarded TETFUND National
Research Fund (NRF) Grant. Figure 37 summarizes how
Kolaviron, a novel chemopreventive agent compromises the
science of the "killers".
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UNIVERSITY OF IBADAN LIBRARY
(a)c_.,unl __ -- -- ••• 1 (b) -"·-1 c-Fos
I ;:======:GAPDHI _________ ...•1GAPDH
'-&::.-12 i.z## ":
8 1 " .&
c•:. 1 '1 fi#
g 0,8 ~ 08 1
0
10,6 LLi! 0.6~ ,
••
~ 0.4 -l .~• 0.4 -'(30,2 " su:-e 0,2'& "'0 _l _° u.. 0-- ~I-,# $" ¢ <" ,# ~'Vcl' .:;.x'r' c,'~<;' 'r' ¢ .:;.x'<r'"
*'" *'"
Fig. 34: Protective effect of kolaviron (KV) on atrazine (ATZ)-induced
alterations in the protein expression of c-Jun and c-Fos (A, B) in
PC12 cells. Source: Abarikwu et at. 2011a.
(a)
" " V
AtR
(b) 20 bed e
18
~ 16
~ 1.•
~ 12
'9 10
.f! 86
#. ••
2
Fig. 35: Kolaviron (KV) prevents atrazine (ATR)-induced apoptosis. SH-
SY5Y cells, with or without simultaneous treatment with KV were
exposed to ATR for 48 h, microscope (magnification, X400). Arrow
heads indicated condensed nuclei and arrow indicated fragmented
nuclei (a), quantification of abnormal nuclei after exposure to ATR in
the presence or absence of KV. Source: Abarikwu et at. 2011 b.
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UNIVERSITY OF IBADAN LIBRARY
(a) [.control mAIl. c
9 --.---------K-V--e-K-v+ATZ I
8'
~ . ••
o 7 I
'~ 6 i
: 5f,·· "'II **
i~ '"I.·li·•·•• #N.
o t~- '. ,. F
ce-s Cas-9 p53 COX-2 Bax
(b) 1.6
~ 1 ••1.4 tf 1.2 1-I
"'Q
'e0::. 1
.~.e..-. 0.8
1
'-.f.l, 0.6
"?
! 0.4
u'e"e
0.2
0
control ATZ KV KV+ATZ
Fig. 36: Real-time quantitative-PCR analyses of mRNA expression of
caspase-3 (cas-3), caspase-9 (cas-9), p53, cyclooxygenase-2 (COX-
2), Bcl-2 and Bax genes in PCl2 cells exposed to kolaviron (KV) and
atrazine (ATZ) alone or in combination for 6 h (A). Caspase activity
(B). Source: Abarikwu et al. 2011b.
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UNIVERSITY OF IBADAN LIBRARY
Chemicals
", ...•..
~ .!l.-- ..• IROS----+_/~ / ...•..~. .' Oxidativsetres~ T'T--<'
-~IBax_ Bcl-2
• •••
+
Caspase +ctivat~
Apoptosi *
Fig. 37: How kolaviron compromises the science of the "Killers".
Conclusion
Mr. Vice-Chancellor, distinguished ladies and gentlemen, I
have in the course of this lecture shown through our series of
studies that humans are advertently and inadvertently exposed
to environmental toxicants especially through diet. Also,
therapeutic drugs especially when taken at overdose are
capable of damaging tissues. Through excessive generation of
free radicals, the tissue defence mechanism can be
compromised and overwhelmed leading to oxidative stress.
Inflammation especially unresolved, is another mechanism of
initiating disease conditions such as cancer. I have also shown
that providentially in our diet, certain protective factors are
inherent in them and capable of preventing, delaying or
reversing diseases caused by these chemicals. In this
connection, chemopreventives with potent antioxidant and
anti-inflammatory properties can compromise the two co-
conspirators employed as veritable tools by the 'killers' in
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UNIVERSITY OF IBADAN LIBRARY
initiating cell dysfunction and death. Therefore, if we invest
in eating these naturally occurring chemopreventive agents,
there is hope that humans can be spared from certain health-
threatening diseases and longevity can be achieved. In actual
fact, there has been a paradigm shift in many countries
(including the USA) from the use of conventional medicine to
naturally-occurring phytochemicals and it has been predicted
that the doctors of the future will prescribe pills made of
phytochemicals and chemopreventives to patients given their
beneficial principles. I will conclude with the words of
wisdom from Hippocrates a celebrated Greek Physician and
adjudged "father of Western medicine" who said "Let
medicine be thy food and food be thy medicine" and "You
are what you eat".
Recommendations
In the course of my training and development of my academic
career, I have by the Grace of God and His Mercy worked in
various world-class laboratories and worked with inter-
national experts in my field of research. I had postdoctoral
training three times in three different laboratories around the
globe and I have been invited to conduct research in many
laboratories abroad as Visiting Scholar and Visiting
Professor. My doctoral students as well as junior colleagues
have also leveraged on this and I have connected them to my
friends and collaborators aboard. Some of them have
conducted certain parts of their PhD work outside the
country. Hence, I have been able to present the information
contained in this lecture to you all. During these visits, I
learnt so many things in terms of research, academic culture
and best practices. The common denominator is actually the
commitment of the government to high quality research and
engagement of scientists to highly competitive and globally-
relevant research. For instance as a Visiting Professor in
Seoul National University, Korea my friend Professor Young-
Joon Surh disclosed that so many Korean Scientists who
trained in the USA were recruited back to the country to
replicate and do the 'wonders' in Korea while they were in
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the USA. They were given space, grants and enabling
environment to do research and compete globally. Mr. Vice-
Chancellor, ladies and gentlemen within a short period of
time the dividend of this investment started showing. In
certain fields of research endeavour and technological
innovations, South Korea is on top today. This country was at
par with Nigeria in the 1960s! This is another opportunity of
calling on the government to invest in quality research. Thank
God the awareness is there as the past Nigerian Government
instituted the National Research Fund scheme under
TETFUND. We need more of this at this time.
Another lesson I learnt while in those institutions abroad
is also the issue of the universities and their focus on certain
specialized research. They have not attempted to shine in all
areas of research but they have strived to be known in certain
focused specialized areas. Many researchers in our
universities are just conducting what I call 'survival' or
racking research, only for the purpose of promotion and to
gain high scores during the usual scoring of papers exercise.
Unfortunately, this will not take us anywhere. I am using this
medium to call on the University management to examine our
research activities critically and focus on certain impactful
research areas that can showcase the University, taking into
consideration the strength and comparative advantage of
researchers in Departments and Faculties.
While the effort to centralize certain equipment may be
good, serious efforts should be made to develop laboratories
based in various departments and equip them with a state-of-
the-art facilities. Most of the equipment we centralize in the
central research laboratories are usually placed on the
corridors of personal laboratories of colleagues abroad. To
my esteemed colleagues especially the younger ones, it is
highly imperative to do away with 'survival' research and go
beyond mere publishing only for the purpose of promotion.
Rather, we should be engaged in cutting-edge research,
highly competitive hypothesis-driven proposals that can
attract international grants to do globally-relevant research. It
is only by engaging in this kind of research that the gown can
effectively impact the town.
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For researchers working in the field of natural product, I
encourage you to dig deeper and stop scratching the problem
on the surface. While the use of extracts may provide some
preliminary information on the therapeutic use of a plant, it is
only isolated and well-characterized compounds that can be
useful in investigating and understanding the underlying
pharmacological basis of action of these plants. Hence, multi-
disciplinary approach involving Biochemists, Chemists,
Pharmacognosists, Toxicologists, Pharmacologists and
Microbiologists is highly needed at this time.
Judging from what I have presented today you will all
agree with me that there is a lot to be done between
biomedical scientists and clinicians. Translational medicine is
actually the future of molecular medicine. The University
should encourage and support translational research through
research funding-taking research products from 'bench to
the bedside'. As a Fellow of the Nigerian Academy of
Science, in the month of September 2015, Professor Fola
Esan (retired Professor of Hematology) and I were privileged
to represent Nigeria and the Academy in Beijing, China on
Inter academy programme. In China, we were exposed to a
lot of translational research and many products actually
developed in the laboratory facilitated by the government and
various universities are useful in Chinese Traditional Medical
Hospitals in treating many health-threatening ailments
including cancer. No wonder, China continues to be a major
exporter of traditional medicinal products to the world market
through well-organized and articulated translational research.
Toxicology is a cross-cutting research field and there is
actually a dearth of trained and qualified toxicologists around
the African continent. Toxicology plays an important role in
detecting poisons, fake drugs, hazardous chemical
compounds, genotoxic agents and dangerous herbal products.
Before taking any natural product to the market, it must have
passed through series of toxicity testing and found not to be
toxic. There is the need for the University to establish viable
and well-equipped toxicity screening center to serve the
nation. In addition, University of Ibadan should have a
Toxicology programme at the postgraduate level to train and
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increase manpower and build capacity in this important field.
During my one-month visit to the Indiana State University,
Bloomington, USA (April, 2014), I discussed this extensively
with the leadership of Society of Toxicology (SOT), USA and
International Union of Toxicology (lUTOX) when I was
honoured with the globally competitive award of the SOT
Global Senior Toxicology Fellowship. Happily, we have the
support of these esteemed organizations and experts in the
field. We need the support of the University management to
actualize this for our University, Nigeria and Africa at large.
Finally, research on chemoprevention should be
encouraged given the role it plays in preventive medicine and
health care delivery system. The Government through the
Ministry of Health should promote and facilitate
chemopreventive initiatives just like many governments
abroad have done in recent years. For instance, a number of
government programmes have been created in the United
States and in Europe to increase vegetable consumption and
plant-based phytochemicals-in order to decrease cancer
incidence and other life-threatening diseases. These include
the following: 'Savor the Spectrum' an initiative that urges all
Americans to eat five to nine servings of colourful fruit and
vegetables a day for better health based on current research
showing that phytonutrients from different colour groups are
powerful disease fighters that help our body fight off cancer
and heart diseases.
European Prospective Investigation of Cancer and
Nutrition (EPIC) is one of the most important multicentre
prospective cohort studies ever launched worldwide involving
more than half a million (520,000) participants recruited by
20 centres in 10 countries under the coordination of the
International Agency for Research on Cancer. (lARC) and .
partly funded by the 'Europe Against Cancer' programme of
the European Commission, as well as by the participating
countries. EPIC focuses on identifying the dietary
determinants of cancer, and is aimed at expanding the
presently limited knowledge of the role of nutrition and other
lifestyle factors in the aetiology and prevention of cancer and
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other life-threatening diseases. These initiatives in place in
Nigeria, will facilitate longevity and accentuate our average
life span, which is currently one of the lowest in the world.
Acknowledgements
For this cause I bow before the Father of light, the Creator of
the ends of the earth, the 'Elohim' of Israel for the avalanche
of grace, mercy and favour bestowed on me without measure.
He is the Lifter up of my head, my Succorer, Standby and
One who causes me to triumph in every situation and make
manifest the savour of His knowledge in every place. Glory
be to His Holy name!
I am highly indebted to my late father Chief Emmanuel
Oyetunji Farombi for his investment in my education and
support all the way. In nostalgia, I remember he used to quote
to me regularly Proverb 22:8 "Seest thou a man diligent in his
business? he shall stand before kings; he shall not stand
before mean men". Today, the fulfillment of this scripture has
come to pass. I am eternally grateful to my mother Mama
Comfort Adegbenle Farombi who is seated here today to
witness this occasion. I thank her for motherly care, love,
concern, affection and constant prayers. Mama may you live
long for more years to come! Amen.
12th century theologia Salisbury said in 1159: "We are
like dwarfs sitting on the shoulders of giants. We see more,
and things that are more distant, than they did, not because
our sight is superior or because we are taller than they, but
because they raise us up, and by their great stature add to
ours. "
My special gratitude to all my mentors starting from my
PhD Supervisor and academic father, Professor Godwin
Onyenoro Emerole for the training, counsel, guidance,
support and encouragement. I appreciate deeply my PhD
External examiner, Professor A.A. Odutuga. I acknowledge
my international collaborators for inviting me to conduct
research in their laboratories and for their wonderful support
namely Professor George Britton, Department of
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Biochemistry, University of Liverpool, Professor Lars
Dragsted, Institute of Food Safety and Toxicology, Soborg,
Denmark, Professor Steffen Loft, Panum Institute University
of Copenhagen, Professor Herman Autrup, Department of
Environmental Health, University of Aarhus, Denmark, Dr.
Peter Moller, Department of Pharmacology, University of
Copenhagen. Denmark, Professor Young-Joon Surh, Seoul
National University, Korea, Professor Beatrice Pool-Zobel
(late), University of Jena, Germany and Professor James
Klaunig, Indiana State University, Bloomington USA. I
acknowledge with thanks the kind cooperation of my friends,
Professor Paul Tchounwou and Dr. Antia Patolla of Jackson
State University (JSU) USA and Professor Ernest Izevbigie,
formerly of JSU and now Vice-Chancellor, Benson Idahosa
University, Professor Okezie Aruoma, American University
of Health Sciences, Signal Hill, USA, Professors Johan
Esterhuyse, Cape Peninsular University of Technology, KS
Mossanda, Walter Sisulu University and Mary Gulumian,
University of Witwatersrand, South Africa.
I acknowledge the funding support of the following
organizations- UNESCO/MCBN, IUBMB, WHOrrDR,
IUTOX, SOT, SFRR-Africa, Danish Research Council, Lady
Bank-Anthony Cancer Research Foundation, Ministry of
Science and Technology of South Korea, National Institutes
of Health (NIH) RCMI-Center for Environmental Health and
the U.S. Environmental Protection Agency.
I am grateful to Professor Olufunso Olorunsogo, current
Head of Department whom I met first in the Department
during my initial registration as first year Biochemistry
student. Ever since he has been very supportive and helpful
and kind. I also acknowledge my former Teachers in the
Department who taught me a lot of things including the
history of Biochemistry. I consider my self a link between the
very old and the younger colleagues in the Department. I
thank Professors Enitan Abisogun Bababunmi, Anthony
Uwaifo, Michael Fafunso (late), Emmanuel Maduagwu, and
S.l. Faparusi. I also thank Drs. A. Adekunle and J.O.
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Nwankwo (now Professor). I appreciate the entire staff of the
Department of Biochemistry: My sister Professor Oyeronke
Odunola, Dr. O.A. Adaramoye, Dr. C.O.O. Olaiya, Dr. M.A.
Gbadegesin, Dr. Sarah Nwozo, Dr. Omolola Adesanoye, Dr.
A. Abolaji, Dr. S. Owumi, Dr. LA. Adedara, Dr. Olanlokun,
Dr. Temitope Ayeotan, Mrs. Toyin Adeyemo-Salami, Mr.
Esan, Miss Bukola Oyebode, Mr. 1.0. Awogbindin, Mr. 1.0.
Olugbami, Mr. A. Olowofolahan and Mr. A.M. Adegoke. I
wish to acknowledge the technical support of two
technologists who assisted me in the early stage of my
academic career-Miss Grace Uloma Nwachuckwu now Mrs.
Grace U. Egemonu (Mama G) and Mrs. Vibeke Kegel,
Institute of Food Safety and Toxicology, Soborg, Denmark.
I thank members of the Faculty of Basic Medical Sciences
for support and for giving me the mandate to lead the Faculty
for four years. I also appreciate all staff of the College of
Medicine currently led by the Provost, Professor B.L. Salako.
I appreciate the friendship of the following-Professors E.A.
Falaye, O.G. Ademowo, A.R.A. Alada, E.A. Ajav, 1.1.
Anetor, B.O. Omitoyin, Y. Raji, Drs. Georgina Odaibo, Gani
Adeniran and many other important people not mentioned. I
thank Professors A.I Ajaiyeoba, O. Oladimeji, A. Ajuwon
and Modupe. Arowojolu who served as colleague Deans in
the College of Medicine and Professors Oluremi
Ogunshehinde (Deputy Provost), A. Ogunniyi (Director of
IAMRAT) (2010-2014) and Mrs 'Bunmi Faluyi (Secretary to
the College).
I thank my postgraduate students, past and present that
worked so hard with me during some of the studies I
presented today. I have trained them to be hardworking,
dogged, dedicated and committed to science. Wherever they
are, they are good ambassadors of sound training and
mentoring. I am deeply grateful to the working group
committee of this inaugural lecture. May God bless you all!
I appreciate all my siblings and their spouses, Evangelist
Akinwumi Farombi, Mrs. Olufunke Sagunna, Mr. Olusegun
Farombi and Pastor (Mrs.) Olufunmilola Alalibo for the love
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and affection we have shared over the years. I thank the
friends of my youth especially my secondary school
classmates at Akinorun Grammar School, lkirun. Many of
them are in this audience today.
I thank the following for enriching my administrative
experience while I was Head of Department and Dean of
Faculty-Professors A.O. Omigbodun and O. Akinyinka
(former Provost, College of Medicine), Professors A. Agbaje,
O. Bamiro, LF. Adewole and O.D. Olaleye, my predecessor
in office as Dean for his kind support and encouragement
over the years.
I thank my research groups and collaborators at Ibadan,
Drs. O.A. Adaramoye, LA. Adedara, A. Abolaji, Omolola
Adesanoye, 1.0. Awogbindin, O. Owoeye, S. Onasanwo,
Professors M.O. Oyeyemi, C.B. Babalola, Kunle Idowu and
S.B. Olaleye who is not only a research collaborator but a
faithful lieutenant, brother and friend. I appreciate my prayer
mentor Rev. (Dr.) Moses Aransiola of Gethsemane Prayer
Ministries and my friends Pastors Victor Okoruwa (now
Professor), Kayode Ojo, Elder Gabriel Akinbola (now
Professor) and some members of the church at a time
including Professors Bankole Oke and his wife my sister
Gbemi Oke, our own DVC Academic, and the Vice-
Chancellor, Professor 1. Olayinka and his wife who were my
parishioners. I appreciate the wonderful spiritual support of
Rev. (Dr.) Gomba Oyor of 'God Will Do It Ministries' and
Apostle Segun Adebowale of Grace and Mercy Ministries. I
cherish the love and support of the Pastorate and the entire
members of the Jesus Covenant Family, RCCG, Ibadan led
by Pastor Wale Akande.
I appreciate my parents in-law Mr. and Mrs. Olonimoyo
and their children for their love. I would like to thank my
darling wife Dr. (Mrs.) Temitope Farombi, my sweetheart
and damsel for your love, and support over the years, and my
children who always wonder why I stay late in the laboratory
and travel outside the country so frequently. I love you so
deeply.
Now unto the King Eternal, Immortal, Invisible, the only
Wise God, the only Potentate, the First and the Last, the
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Alpha and Omega, the Sovereign Father, Eternal Refuge, my
Helper and Pillar of Support. By Him I have run through
several troops and by Him I have leaped over the wall. He
made me a fruitful bough by the well with branches running
over the wall. Yea my bow abide in strength and the arms of
my hands have been made strong by the hands of the
Almighty. To Him alone be the Glory, the Honour, the
Power, the Might, the Victory and the Majesty for ever and
ever.
Mr. Vice-Chancellor, distinguished ladies and gentlemen
"Hitherto the Lord has helped me (Ebenezer)". I thank you
all.
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BIODATAOF
PROFESSOR EBENEZER OLATUNDE FAROMBI
Ebenezer Olatunde Farombi was born in Osogbo, Osun State
to the family of Late Chief Emmanuel Oyetunji Farombi and
Chief (Mrs.) Comfort Adegbenle Farombi. After his primary
education, he attended Akinorun Grammar School, Ikirun
where he obtained the West Africa School Certificate with
Division 1 and he was the Library Prefect. He had his A'
Levels at the Polytechnic Ibadan. Thereafter, he proceeded to
the University of Ibadan to study Biochemistry and graduated
as the only candidate with Second Class Upper Division and
was the best student in his graduating class. After the
compulsory NYSC, he returned to the University for
postgraduate studies for which he was awarded the Federal
Government of Nigeria Scholarship. He obtained his MSc
degree in Biochemistry and again he was the overall best
student and the only candidate with PhD grade in his
graduating class.
His academic career in the University began in 1988 as
practical class demonstrator in Biochemistry, Graduate
Assistant in 1989, and Assistant Lecturer in March 1990.
During his doctorate programme, he enjoyed two fellowships
Bassir Thomas Research Fellowship and Cadbury PIc
Postgraduate Fellowship and he was the first to receive the
prestigious Award. He rose steadily and consistently through
the ranks of the promotion ladder of the University. He
became Lecturer II in 1993, Lecturer I in 1997, Senior
Lecturer in 2000, Reader in 2003 and Professor of
Biochemistry on October 1, 2006.
After his PhD in 1995, he proceeded to the University of
Liverpool, England for postdoctoral training with Dr. George
Britton as his preceptor. He had another postdoctoral training
in Denmark between 2001 and 2002 where he worked with
three giants in the field of chemical carcinogenesis-Dr. Lars
Dragsted of the Institute of Food Safety and Toxicology,
Soborg, Professor Steffen Loft, Panum Institute, University of
Copenhagen and Professor Herman Autrup of the Department
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of Environmental Health, University of Aarhus, Denmark. He
was at different times Visiting Professor to the National
Research Laboratory of Molecular Carcinogenesis and
Chemoprevention, Seoul National University, South Korea
(2005/2006); the Department of Nutritional Toxicology,
Friedrich-Schiller University of Jena, Germany (2007);
College of Science, Engineering and Technology, Jackson
State University, Jackson, Mississippi, USA (2009, 2010);
Cape Peninsular University of Technology, Cape Town,
South Africa (2011); University of Chicago Medical School,
USA (2011); Indiana University, Bloomington, USA (2014)
and China Academy of Chinese Medical Sciences, Beijing
China (2015).
Worthy of note, his scientific impact nationally and
globally has been recognized. For instance in 2005, he was
cited and listed among top 10 productive researchers in
University of lbadan who contributed research articles within
a 10 year frame (1995-June 2005)- (SESRTCIC,
http://sesrtcic.org/statisticstate) and ten years later, following
the February 2015 Webometric Ranking of Nigerian
Scientists, he was top-rated (ranked number 1 Nigerian
scientist) with h-index of 35, ilO-index of 86 and 4,156
citations. He is a recipient of several International
Fellowships and Grants including: UNESCOIMCBN (1998);
IUBMB (1998, 2003); WHOfIDR (1998) Fellowships;
Danish Research Council Grant (2002); Lady Bank-Anthony
Cancer Research Grant (2004), Seoul National University,
Korea Visiting Professorship Grant (2005), the MacArthur
Foundation Grant for Multidisciplinary Team Research on
Chemoprevention (2009), The MacArthur Foundation Grant
for Specialized Linkages in the special area of Biotechnology
and Medicinal Chemistry (2008, 2009) and 2012 IUTOX
Fellowship. Professor Farombi was the winner and recipient
by open international competition of the 2014 SOT Global
Senior Toxicology Award for his outstanding contribution to
the Science of Toxicology.
A very effective, productive and innovative researcher,
supervisor and mentor, he has supervised 150 MSc
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dissertations and 19 PhD theses in Biochemistry and
Toxicology and several BSc students' projects. He is the
supervisor of the adjudged best PhD Thesis in the discipline
of Basic Medical Sciences within the Nigeria University
system during 2009 assessment by NUC. He has edited a
book on Cancer Chemoprevention and has published 165
scientific articles in reputable international journals, 12
chapters in books, and has given over 100 scientific lectures
in countries spanning four continents of the world. He is the
Foundation Editorial Board Chairman of the Archives of
Basic and Applied Medicine (ABAM) and Foundation
Editor-in-Chief of Toxicology Digest, the official journal of
West Africa Society of Toxicology (WASOT).
He has held several administrative positions including:
Sub-Dean Postgraduate, Faculty of Basic Medical Sciences
(2006-2008), Head of Biochemistry Department, (February
1St, 2008- 31st July, 2010), Coordinator, Zonal Committee,
National Biotechnology Development Agency (NABDA)
Zonal Biotechnology Centre (October 2008-2009), Leader,
University of Ibadan Biotechnology Center of Excellence
Project (November 2009-2010), Dean, Faculty of Basic
Medical Sciences (2DlO-2014), Acting Director, Institute for
Advanced Medical Research and Training (IAMRAT) (1st
May_31st July 2011) and Acting Provost, College of
Medicine, University of Ibadan (2010-2014) (on several
occasions).
In the course of his scientific career, he has been
honoured with prestigious professional awards: He is a
Fellow of the Royal Society of Chemistry (FRSC) UK,
Fellow Nigerian Academy of Science (PAS), Fellow
Academy of Toxicological Sciences (FATS) of the USA and
recently, he was admitted to the Fellowship of the African
Academy of Science (FAAS), being the first Nigerian
Biochemist to be so honoured. He is happily married to Dr.
(Mrs.) Temitope Farombi a Senior Registrar, University
College Hospital, Ibadan and they are blessed with three
children.
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NATIONAL ANTHEM
Arise, 0 compatriots
Nigeria's call obey
To serve our fatherland
With love and strength and faith
The labour of our heroes' past
Shall never be in vain
To serve with heart and might
One nation bound in freedom
Peace and unity
o God of creation
Direct our noble cause
Guide thou our leaders right
Help our youths the truth to know
In love and honesty to grow
And living just and true
Great lofty heights attain
To build a nation where peace
And justice shall reign
UNIVERSITY OF IBADAN ANTHEM
Unibadan, Fountainhead
Of true learning, deep and sound
Soothing spring for all who thirst
Bounds of knowledge to advance
Pledge to serve our cherished goals!
Self-reliance, unity
That our nation may with pride
Help to build a world that is truly free
Unibadan, first and best
Raise true minds for a noble cause
Social justice, equal chance
Greatness won with honest toil
Guide our people this to know
Wisdom's best to service turned
Help enshrine the right to learn
For a mind that knows is a mind that's free
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UNIVERSITY OF IBADAN LIBRARY
UNIVERSITY OF IBADAN LIBRARY