FACULTY OF PHARMACY

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Visible spectrophotometric determination of Furosemide in dosage forms following its hydrolysis and Diazo coupling with Chromotropic Acid
(Nigeria Association of Pharmacists in Academia, 2023) Thomas, O. E.; Adegoke, O. A.; Taiwo-Ojediran, B.
Background: Several previously reported visible spectrophotometric methods for the quantification of furosemide in dosage forms are fraught with poor specificity due to background absorptivities of other chemical species in the sample matrices. Objective: To develop a simple, sensitive and specific visible spectrophotometric method for the quantitative determination of furosemide in bulk and dosage forms. Method: The new spectrophotometric method was based on acid-hydrolysis of furosemide followed by its diazotization and coupling with chromotropic acid to generate a red adduct. Reactions variables critical to optimal response were established. Various analytical and validation parameters including repeatability, reproducibility and selectivity were also determined. Results: The calibration graph was linear between 8.09 μg/mL to 161.8 μg/mL at 503 nm with a correlation coefficient of 0.992. The Sandell’s sensitivity of the new method was 0.14 μg.cm-2/0.001 A.U. while the limits of detection and quantification were 0.75 and 2.28 μg/mL respectively. The method was accurate and precise with recovery in the range of 102.24–109.92% and intra- and inter-day precision (%RSD) at three different concentrations less than 2.0%. When applied to the analysis of dosage form, there was no statistical difference between the newly developed and official methods. There was no interference from commonly used excipients or background absorptivities in the sample matrices. Conclusion: In comparison with some previously reported colorimetric methods, the new method reliably quantified furosemide over a wider range of concentration and with a superior level of sensitivity. The new method can serve as a reliable alternative to the official method for analysis of furosemide.
In vitro cytotoxicity, genotoxicity and apoptoxicity of 8-hydroxy-3,6-disulphonaphthyl azohydroxynaphthalenes using Human Lymphocytes: Experimental and theoretical profiling
(Taylor & Francis, 2023) Thomas, O. E.; Adegoke, O. A.; Mukherjee, A.; Banerjee, R.
Regulatory agencies require demonstration of non-genotoxicity of new chemical entities prior to their use as pharmaceuticals or additives. Consequently, the in vitro cytotoxicity, genotoxicity and apoptoxicity of five novel monoazo colourants (8-hydroxy-3,6-disulphonaphthyl azohydroxynaphthalenes, 3a-e) on human lymphocytes were evaluated using a cell viability assay, alkaline comet assay, DNA diffusion assay, DFT calculations and molecular docking. The test concentrations of the compounds varied from 0 to 3.4 mM. Relative to negative control, the compounds at concentrations up to 0.5mM induced small dose-dependent reduction (< 20%) in viability of lymphocytes. Statistically significant changes (p<0.05) in DNA damage parameters (percent tail DNA, tail extent moment, olive tail moment) were observed at all concentrations of 3a, 3b while 3c-e showed genotoxicity at 2.8, 0.17 and 3.4 mM respectively. Compounds 3a, 3b, 3d induced apoptosis at concentrations below cytotoxic doses while 3c and 3e were non-apoptoxic at all test concentrations. DFT calculations showed the genotoxicity of 3a-e increased with electrophilicity and ionization potentials of the compounds. Molecular docking of 3a-e with apoptosis-associated proteins revealed binding affinity patterns that were consistent with observed experimental apoptoxicity. The structure-genotoxicity relationships of five novel monoazo compounds, which can be employed in the design of safer congeners, have been elucidated.
Characterization, antimicrobial and catalytic activities of silver nanoparticles biosynthesized using Aqueous extract of Euphorbia graminea
(Istanbul Medipol University, 2023) Thomas, O. E.; Alabi, S. O.; Osharode, P.E.
Phytosynthesis of silver nanoparticles (AgNPs) is not only affordable and ecofriendly but provides a means of synthesizing phytochemical capped AgNPs with predefined characteristics. The objective of this study was the green synthesis of AgNPs that possess antimicrobial and catalytic activities using aqueous extract of Euphorbia graminea. Reactions parameters critical to the yield, size and morphology of the biosynthesized AgNPs were optimized using UV spectroscopy. The UV-visible spectra analysis of the biosynthesized AgNPs showed surface plasmon resonance occurred at 462 nm. Scanning Electron Microscopy with Energy dispersive X-ray analysis revealed the characteristic absorption band of AgNPs at 3 KeV and confirmed 73.66% composition of particles as metallic silver. The AgNPs appeared as well-separated, quasi-spherical particles with narrow size distribution of 6.77±0.89 nm when examined with Transmission electron microscopy. X-ray diffraction confirmed the crystallinity of the AgNPs with mean crystallite size of 7.65 nm. The biosynthesized AgNPs showed broad-spectrum antimicrobial activity against bacteria and fungi. The rate constant of the degradation of methylene blue in the presence of as-synthesized AgNPs was increased several folds to sec-1 from sec-1 in its absence. The prepared AgNPs could find applications as therapeutic.
Comparison of the Calf Thymus DNA Binding Interactions of 5-hydroxymethylfurfural and its Synthesized Derivative, 5, 5’[oxy-bis(methylene)]bis-2-furfural: Experimental, DFT and Docking Studies.
(Taylor & Francis, 2023) Thomas, O. E.; Oduwole, R. T.; Akin-Taylor, A.
In this study, the in vitro DNA-binding interactions of the food/drug additive, 5-hydroxymethylfurfural (HMF) and its major degradant, 5, 5’[oxy-bis(methylene)]bis-2-furfural (OBMF) were investigated. OBMF was synthesized and characterized using IR, NMR and mass spectrometry. Photometric titrations revealed OBMF induced more extensive perturbations in the 258nm band of DNA and exhibited binding constants that were 5–12-folds higher than those of HMF. The greatest net changes in viscosity of DNA induced by HMF and OBMF were 10.5 and 8.9%, respectively which confirmed both compounds as minor groove binders. Docking revealed that OBMF and HMF bound to the guanine–cytosine regions of minor groove of DNA with global binding energies of −36.36 and −26.12 kcal/mol, respectively. DFT calculations revealed the higher electrophilicity of OBMF contributed to its increased interaction with the negatively charged DNA backbone. There is a need for stricter control of permissible levels of OBMF in food and drug products.
Phytosynthesis, Antimicrobial and Catalytic Activities of Silver Nanoparticles derived using Leaf and Stem Extracts of Indigofera macrophylla
(Nigeria Association of Pharmacists in Academia, 2022) Thomas, O. E.; Adegoke, O. A.; Adeniyi, E. M.; Oliver, C. G.
Background: The phytosynthesis of metal nanoparticles is a promising green alternative to traditional chemical approaches. Objective: The aim of this study was to synthesize silver nanoparticles (AgNPs) with antimicrobial and biocatalytic activities using aqueous leaf and stem extracts of Indigofera macrophylla. Methods: Critical reaction variables for the biosynthesis of AgNPs were optimized using UV-vis spectroscopy before the biosynthesised AgNPs were characterized using various spectroscopic and microscopic techniques. The biological activities of the biogenic nanoparticles were then investigated with particular focus on their antimicrobial activity and biocatalytic efficiency in the degradation of methylene blue. Results: The surface plasmon resonance of silver nanoparticles biosynthesized using aqueous extracts of leaf (LEAgNPs) and stem (SE-AgNPs) of I. macrophylla occurred at 430 and 426 nm respectively. Scanning electron microscopy images of the nanoparticles showed highly aggregated polymorphs with mostly spherical shape. The particle sizes of LE-AgNPs and SE-AgNPs as determined by Transmission electron microscopy were 48.61±8.60 and 18.09±4.13 nm respectively with Energy dispersive X-ray analysis confirming characteristic absorption band at 3 KeV. In susceptibility assays, LE-AgNPs showed dose-dependent zones of inhibition against Escherichia coli (18mm), Staphylococcus aureus (18 mm), Pseudomonas aeruginosa (20 mm) while SE-AgNP was only active against Staphylococcus aureus (10 mm). Both LE-AgNPs and SE-AgNPs showed good biocatalytic efficiency in the degradation of methylene blue with rate constants of 0.0204 and 0.0182 min-1 respectively. Conclusion: Silver nanoparticles with antimicrobial and catalytic activities have been biosynthesized using the aqueous extract of Indigofera macrophylla.
Preferential solvation of 4-carboxyl-2, 6-dinitrophenylazohydroxynaphthalenes in mixed hydroxylic solvents
(Nigeria Association of Pharmacists in Academia, 2021) Thomas, O. E.; Adegoke, O. A.; Adenmosun, F. G.; Abiodun, O. J.
Background: The applications of a group of 4-carboxyl-2,6-dintrophenylazohydroxynaphathalenes, AZ-01 to 04, as colourants, chemosensors or synthetic intermediates have been limited by their solubility. Aim: To investigate the effect of solvent mixture composition on the solubility, solution thermodynamics and position of equilibrium processes of the dyes. Method: The UV-visible spectral patterns of the dyes in binary mixtures including Methanol:Water, Ethanol:Water, Methanol:Ethanol, Methanol:Propan-1-ol, Methanol:Propan-2-ol, Propan-1-ol:Water and Propan-2-ol:Water were acquired. The type and quantitative estimation of solute-solvent interactions at play were determined by fitting spectral patterns to solvent parameters using multilinear regression. Results: Preferential solvation was detected by the non-ideality of the plots of E12 as against the mole fractions of cosolvent in all binary mixtures. In pure solvents, the spectral shifts of AZ-01, 03 and 04, which exist predominantly in the hydrazone form, were affected by polarity of solvent milieu while solvent basicity and acidity, in that order, were the significant parameters for AZ-02. In aqueous alcoholic mixtures, solvent polarity was contributory, although to different degrees, to the observed spectral data of the four dyes. However, solvent acidity and basicity were the primary determinants of spectral shifts observed with AZ-04 and AZ-03 respectively. Spectra-structure relationships identified the formation of the charged hydrazone tautomer which requires stabilisation by polar solvent milieu as responsible for the observed trend. In addition, interactions between new aggregated solvent-solvent species and the propionic acid substituent present in AZ-03 contributed to its spectral shifts. Conclusion: The solvatochromic properties of the phenylazonaphthalene series in binary mixtures have been successfully studied.
Heavy Metal Contamination of Paediatric Paracetamol and Ascorbic Acid Drug Products in South-West Nigeria.
(West African Postgraduate College of Pharmacists (WAPCP), 2019) Thomas, O. E.; Itopa, M. O.; Adegoke, O. A.
Background: Water is a primary contributor to human populations’ heavy metals exposure and industrial contamination of products. Consequently, paediatric medications because of their high-water constitution can contribute significantly to intake of heavy metals in excess of allowable limits. There is therefore a need for effective preventive and control strategies. Unfortunately, studies investigating heavy metal content in paediatric formulations in Nigeria are scarce and often limited in the range of elements assayed. Objective: To evaluate elemental impurities in the two most frequently administered paediatric medications-paracetamol and ascorbic acid marketed in South-west Nigeria. Methods: Thirteen paediatric syrup brands were used for the study. Sample pretreatment involved dry ashing followed by digestion using concentrated aqua regia (nitric acid:hydrochloric acid, 3:1). Chromium, lead, copper, cadmium, zinc, nickel, cobalt and manganese were assayed with the atomic absorption spectrophotometer with the limit of detection set at 0.001. Results: The most abundant metal ions present in all the formulations were chromium (1.16-1290.2 mg/) and nickel (2.37-1289.0 mg/L). Cadmium was detected at low concentration in only two of the brands while lead was detected in three brands at concentrations ranging from 0.09 - 0.12 mg/L. The calculated expected daily exposures of lead in the three brands were in excess of the permissible daily exposure for oral drug products. Conclusion: Some of the paracetamol and vitamin C syrups sold in the South-West of Nigeria are contaminated with cadmium, nickel and lead.
Two New Spectrophotometric Methods for the Determination of Isoniazid in Bulk Form and Tablet Dosage Form.
(Istanbul Medipol University, Faculty of Pharmacy, 2019) Adegoke, O. A.; Thomas, O. E.; Babatunde, D. I.; Oyelami, O.; Adediran, A.; Omotosho, A.
To develop two new spectrophotometric methods for the analysis of isoniazid in bulk form and tablets. The methods involved condensation of isoniazid with salicylaldehyde and diazo coupling with diazotized p-nitroaniline. Critical factors were optimised; evidence for new product formation, selection of analytical wavelengths, temperature and time and solvent for dilution. Validation was carried out according to ICH guidelines. The new methods were used for isoniazid tablets. Isoniazid formed an imine and azo adduct readily with the two reagents at 30 ⁰C after 5 and 20 mins, and determined at 405 and 420 nm, respectively. Low LODs were obtained for the two methods and recoveries were generally above 98%. The methods were successfully adopted for the assay of isoniazid in tablets and there were no significant differences in the contents when compared with the official titrimetric method of analysis. The methods could find application as in-process method in pharmaceutical industries.
A New Method for the Microdetermination of Para Aminophenol in Generic Brands of Paracetamol Tablets
(Taylor & Francis Group,, 2019) Adegoke, O. A.; Thomas, O. E.; Amao, S. A.; Agboola, S. O.; Omotosho, A. E.
In Nigeria, paracetamol is readily available in several retail outlets where the conditions of storage can be poor leading to elevated levels of para-aminophenol (PAP), which is known to be nephrotoxic and hepatotoxic. However, the routine analysis of PAP is mostly by chromatographic separation which requires expensive instrumentation not often available in developing countries. The objective of this research was to develop a sensitive colorimetric method for the quantification of PAP in paracetamol. The method was based on the diazo coupling reaction between diazotised PAP and chromotropic acid. Various reaction parameters critical for optimal detector response were optimized. The validation of the new method was done following the determination of parameters including repeatability, reproducibility and selectivity using current ICH guidelines. The new method was also applied to the assay of PAP in 14 paracetamol tablet samples. The calibration was linear between 0.0297 and 0.2229 mg/mL at 470nm with limits of detection and quantification of 0.0061 and 0.0185 mg/mL, respectively. The recovery was in the range of 95.96 and 102.21 while intra- and inter-day precisions at three different concentrations did not exceed 4.03%. The new method was successfully applied to quantify PAP in paracetamol with percent content varying from 0.14 to 0.21%w/w. A simple and reliable method for the quantification of PAP has been developed and successfully employed to report, for the first time, the presence of the degradation product at levels beyond the allowable limits in paracetamol dosage forms in Nigeria.
Preferential Solvation of Mordant Black and Solochrome Dark Blue in Mixed Solvents Systems.
(Sami Publishing Company, 2019) Thomas, O. E.; Adegoke, O .A.; Kazeem, A. F.; Ezeuchenne, I. C.
In this study, the preferential solvation of Mordant Black and Solochrome Dark Blue were investigated in mixed solvent systems of aqueous methanol, ethanol, propan-1-ol, propan-2-ol, methanol: ethanol, ethanol:propan-1-ol, methanol:propan-2-ol, ethanol:propan-1-ol, ethanol:propan-2-ol, propan-1-ol:propan-2-ol and carbon tetrachloride: dimethylformamide. Results showed a deviation of solvation data from ideality over the majority of composition ranges in all the solvent mixtures. The type and contribution of specific and non-specific solute-solvent interactions were analyzed in the framework of the linear solvation energy relationships. Statistical analysis of single, dual, and multiparametric equations revealed that in pure solvents, spectral behaviours of MB and SDB were affected by the polarity and basicity of the solvent milieu respectively. However in aqueous alcohols, polarity of the solvent milieu was the most significant determinant of spectral patterns with α and β parameters playing secondary contributory roles in the spectral changes of MB and SDB, respectively. Multiparametric equations generally yielded the best fitted model in mixed alcohol systems with polarity remaining the largest contributor, followed by β and α of the solvent milieu in that order. Spectral-structure relationships identified ion-dipole interactions involving the charged sulphonate and hydrazone moieties as well as protondonor-acceptor interactions of the common labile hydroxyl groups as mechanisms for the observed solvation data.

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