Chemistry
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Item PHYTOCHEMICAL AND PHARMACOLOGICAL EXAMINATION OF ENTANDROPHRAGMA ANGOLENSE AND CRYPTOLEPIS SANGUINOLENTA(1994-03) KOLAWOLE, A. J.Dried, pulverized stem bark and the root bark of Entandrophragma anqolense were separately extracted with methanol. The crude methanolic extract of the stem and root bark of E. anqolense were subjected to column fractionation and purification. This exercise afforded the Isolation of methyl angolensate, 2.26% yield from the stem bark and 0.27% yield from the root bark. The effect of the crude methanolic stem bark extract was investigated on indomethacin-induced gastric ulcer in rats. Its effect was dose-dependent, doses ranging from 0.4 to 1.6 gkg-1 body weight (BW) produced significant effect (P < 0.05). At the highest dose used (1.6gkg-1 BW), complete inhibition of ulceration occurred. Toxicity study showed that the extract was not toxic when doses ranging from 20-200gkg-1 BW was administered to experimental rats. It was established that methyl angolensate is the major anti- ulcer principle present in the methanolic extract of the stem bark of E. angolensate. Methyl angolensate produced a dose-related inhibition of gastric ulceration induced by indomethacin, 40mgkg BW being more effective than 40mgkg-1 BW of propanolol. 80mgkg-1 BW of methyl angolensate completely inhibited gastric ulceration. Methyl angolensate also significantly reduced gastric acid secretion induced by histamine and carbachol (1.0mgkg-1 BW). Thus we confirmed that methyl angolensate produces its anti-ulcer activity through inhibition of gastric acid secretion. The roots of Cryptolepis sanquinolenta were extracted with methanol. Column fractionation of the methanolic extract afforded the Isolation of a new benzocarboline alkaloid labelled (CS-1) melting point 272-274°C. Spectroscopic analysis of CS-1 including the infra-red (IR), 13 ultra-violet (UV), mass spectrum (MS), proton and C-nuclear magnetic spectroscopy were reported. This new alkaloid exhibited anti-microbial activity on five pathogenic organisms. The in-vivo anti-malarial study of the aqueous extract of the roots of sanguinolenta was done on Plasmodium yoeli nigeriensis in mice. Anti-malarial activity of the extract was determined by examining the blood schizontocidal action in established infection using chloroquine as Standard drug for comparison. The extract showed a dose-dependent effect against the malarial parasite.Item DEVELOPMENT OF RESIN-BOUND REAGENTS FOR ANALYSIS OF CARBOXYLIC ACIDS AND AMINES(1993-12) ADEWUYI, G. O.Resin-bound-reagents made up of ionically-bound 2- naphthalene-methanol and covalently bound and sodium-benzoxazole- 2-sulfonate have been synthesized and utilized as analytical reagents for the pre-chromatographic derivatization of fatty acids (i.e. acetic, lauric, capric, hexanoic, octanoic, nonanoic, palmitic, docosanoic linoleic), 1° and 2° aliphatic amines and amino acids respectively. The reagents have been designed to contain fluorescent moieties attached to the anionic and cationic resin backbones through sulfonated ester linkages. These moieties imparted UV and FL detector properties to the final derivatives. The derivatization reactions were performed before the thin- layer Chromatographie separations. Standards we,-e prepared and were used in monitoring the extent of reactions on the resin support. The derivatives were chromatographed and fluorescent spots were observed under UV light. These solid phase derivatizations have led to preliminary investigation of these two functionalities before embarking on instrumentation analysis such as high performance liquid chromatography with UV or fluorescence detection and HPLC-MS Identification.Item METAL(II) TETRAFLUOROBORATE COMPLEXES OF SOME DICARBOXYLIC ACID HYDRAZIDES(1990) ADENIYI, A. A.Eighty-eight divalent metal complexes derived from dihydrazides of oxalic, malonic, succinic, adipic, phthalic and terephthalic acids, with manganese( 11), cobalt(ll), nickel(ll), copper(IJ), zinc(ll), cadmium(ll), mercury(ll) and magnesium tetrafluoroborates have been prepared. The effect of 1:1 and 1:2 metal to ligand reactant ratios have been examined. The complexes have been characterized on the basis of their analytical data, magnetic susceptibility, electronic and IR spectral studies as well as conductance measurements. Reactions involving 1:1 and 1:2 metal to ligand ratios gave complexes with different metal to ligand stoichiometry in most cases. It is evident, from the analytical data, that complexes precipitated out mostly with 1:2 and 1:3 metal to ligand stoichiometry. However, complexes of oxalic dihydrazide with Cu (II) and Hg (II), succinic dihydrazide with Co (II), Ni(ll), Zn(ll) and Mg prepared using a 1:1 molar reactant ratio contained one and a half moles of ligands. Similarly, complexes of Mn(ll), Ni(ll) and Hg(ll) prepared using a 1:2 molar ratio of metal salt to adipic dihydrazide contained one and a half moles of adipic dihydrazide. Nevertheless, reactions involving 1:1 and 1:2 molar reactant ratios gave the same set of compounds in phthalic dihydrazide with Co(ll), Ni(ll) and Zn(ll) tetrafluoroborates respectively. Likewise the complexes of adipic and malonic dihydrazides with Zn(BF4)2 .6H2O4 and Cd(BF4)2 .7H2O respectively. The complexes have poor solubilities in methanol, ethanol, acetone, nitrobenzene, nitromethane, benzene, hexane, aceto- nitrile, dimethylformamide, dimethylsulfoxide and water. But the complexes of inanganese( 11), cobalt(ll), zinc(ll) and cadmium(II) with oxalic, malonic, succinic and adipic dihydrazides were found to be soluble in water. Similarly, nickel(11), CO ppe-f (11) and magnesium complexes of malonic and succinic dihydrazides were soluble in water, so also is the complex of mercury(ll) with adipic dihydrazide. In addition, the complexes of succinic dihydrazide, with manganesef11) and cadmium(ll) tetrafluoroborates were soluble in dimethylsulfoxide. The infrared spectra indicate that the bonding sites in these compounds are the carbonyl oxygen and the amino or amide nitrogens. The electronic and magnetic data of the complexes of manganese( 11), cobalt(ll), nickel(ll) and copper(ll) at room temperature suggested that they assume octahedral geometry. Generally, for a given ligand, the 1:2 complex has a lower magnetic moment than the 1:3 complex. The Variation of the moments with chain length does not appear to be systematic at room temperature. However, the magnetic moments for the Zn (11), Cd(II), Hg(ll) and Mg indicates that they are diamagnetic with some evidence of polarization paramagnetism. The conductance data of the complexes that were soluble in water and dimethylsulfoxide revealed 1:2 type electrolytes.Item SECONDARY METABOLITES FROM A LOCAL MEDICINAL PLANT - GARDENIA ERUBESCENS. STAPF. AND HUTCH(1995-03) ADELAKUN, E. A.A detailed Chemical analysis of the stem of Gardenia erubescens Stapf. & Hutch. was carried out. The crushed stem was sequentially extracted with petroleum ether, ethyl acetate and methanol. Subsequently the Petroleum ether, ethyl acetate and methanol extracts when subjected to phytochemical tests revealed the presence of steroids, flavonoids and saponins, while anthraquinones and alkaloids were not detected. The petroleum ether extract and the n-butanol soluble fraction of the methanol extract were further subjected to chromatographic analyses using a combination of column, TLC and preparative TLC. The TLC analysis of petroleum ether extract showed the presence of steroids and flavonoids as the major components. TLC analysis of the n-butanol soluble fraction of methanol extract however revealed only the presence of saponins. Purification of the petroleum ether extract on column of silica gel afforded, after further purification by preparative TLC, five known compounds, one fraction containing isomerie mixture of two compounds and one new bisnortriterpenoid compound. From the saponin fraction of the n- butanol soluble fraction of methanol extract, five compounds were isolated and identified. Four of these compounds were known while one was a new_ oleanene-type compound. A total of fourteen compounds were isolated and identified from both the petroleum ether extract and n-butanol soluble fraction of the methanol extract of the stems of Gardenia ernbescens. Characterization of the known compounds was achieved through spectral correlation with authentic samples and/or derivatisation and comparison of melting points with the known compounds. Full characterization of the new compounds was accomplished by use of 2D nmr experiments - COSY and 1H-13C nmr correlation spectra, assisted by NOE difference spectroscopy. The known compounds isolated and identified from Gardenia ernbescens in this work were: •D-Mannitol •Stigmasterol •Stigmasterol-3β-D-glucopyranoside •5-Hydroxy-7,4'-dimethoxyflavanone •5-Hydroxy-7,4'-dimethoxyflavone •5-Hydroxy-7,3',4'-trimethoxyflavanone •3β-Acetoxyolean-12en-30-oic acid •Isomerie mixture of oleanolic and ursolic acids •3β,23-Dihydroxyolean-12-en-28-oic acid •2β,3β -Dihydroxyolean-12-en-28-oic acid •2β,3β,23-Trihydroxyolean-12-en-2 8-oic acid and the two novel compounds were: •Erubescenone and •3β,23,24-Trihydroxyolean-12-en-28-oic acid.Item A SEMI-EMPIRICAL SELF-CONSISTENT FIELD MOLECULAR ORBITAL (SCF-MO) STUDY OF THE GROUND STATE PROPERTIES OF SUBSTITUTED NAPHTHALENE COMPOUNDS(1990-03) ADEKUNLE, A. O.The ground and excited state properties of naphthalene and some of its derivatives have been studied. The molecular orbitals were evaluated using the modified Huckel Molecular Orbital (HMO) theory and the calculated molecular properties such as dipole moments, electronic transition frequencies, have been compared with experimental values. The electronic absorption spectra of some of the compounds were further studied in detail as to their band systems and characteristics, solvent polarity effects and hydrogen bonding effects. The dipole moment changes from ground to excited states were generally determined to be high. A linear regression analysis obtained for plots of the 'L(b) band maxima (υ(obs) versus solvent physical properties and solvent empirical parameters has shown that there is no meaningful correlation between solvent dielectric constant (ɛ) and solvent induced shifts. The oscillator strengths have been found to be generally low for the examined compounds in all the solvents. However, the electronic relaxation times calculated for each of the compounds give strong indication as to the likelihood of the band systems arising from mixed states. The relationship between relaxation times, t, and solvent viscosities,ᶯ, allows the prediction of large changes in spherical symmetries of the two band systems ('La and ’Lb) in both 1-naphthylamine and 4-nitro-l-naphthylamine. A possible existence of free internal rotation in the excited states of these molecules, has thus been suggested. The infrared spectra have been studied in the solid state and in solution and the vibrational frequencies assigned by making correlations with spectra of substituted benzene compounds and other related compounds. The substituent modes for each of the compounds have been discussed in detail.Item EFFECT OF ELECTROSTATICALLY LINKED IONIZABLE GROUPS ON SULPHYDRYL REACTIVITIES OF HEMOGLOBINS(1990-03) ABOLUWOYE, C. O.The kinetics of the reactions of two sulphydryl reagents with the CysF9(93)β sulphydryl group of various human and animal hemoglobin derivatives have been studied as a function of pH at 20°C, at an ionic strength of 0.05 M. A quantitative analysis of the data was possible only for the 2,2'-dithiobispyridine data. For the 5,5'-dithiobis[2-nitrobenzoic acid] data, the equation relating the apparent second order rate constant to the model parameters was complex and therefore not useful for quantitative analysis. However, interesting results were observed for the 5,5'-dithiobis [2-nitrobenzoic acid]reaction. As a general conclusion, it is suggested that the reactivity of the CysF9(93)β sulphydryl , depends on two factors: the conformation of the sulphydryl group and the electrostatic effects of the charged ionizable groups on the protein. In order to determine the nature of the charged groups affecting sulphydryl reactivity, the reaction of hemoglobin with another sulphydryl reagent, was studied by potentiometric difference titration as a function of pH at 20°C and ionic strength O.05M. Differences were observed for various derivatives for the parameter Δh+ the number of protons released per sulphydryl group reacted. These differences reflect differences in tertiary structure between the derivatives studied rather than differences in quaternary structure.