Pharmaceutical Chemistry
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Item 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.Item 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.Item 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.Item 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.