Department of Chemical Sciences
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Browsing Department of Chemical Sciences by Author "Ajibade, Sunday"
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- ItemAdicardin and Other Coumarins from Breonadia salicina (Vahl) Hepper(Tropical Journal of Natural Product Research, 2019) Ajibade, SundayBreonadia salicina is an ethnomedicinal plant used in North Central Nigeria to treat sleeping sickness and respiratory diseases. The stem bark of the plant was extracted with methanol and the extract partitioned between dichloromethane and water. The dichloromethane soluble portion was subjected to column chromatography which resulted in the isolation of 7-(β-D apiofuranosyl (1-6)-β-D-glucopyranosyl) umbelliferone, α-amyrin, stigmasterol, 7-hydroxycoumarin and 6- hydroxy-7-methoxy coumarin. The structures of these compounds were elucidated based on NMR spectral analysis. This is the first report of these compounds from the plant.
- ItemBiochemical Properties, In-Vitro Antimicrobial, and Free Radical Scavenging Activities of the Leaves of Annona muricate(Journal of Appl. Sci. Environ. Manage., 2017) Ajibade, SundayFifteen (15) male Wistar rats were completely randomized into three (3) groups. Group A was normal control, Group B received 200 mg/kg weight of ethyl acetate extract of Annona muricata leaves (AMLE) and Group C received 100 mg/kg b.weight AMLE. Single daily dose of AMLE was administered orally for twenty one (21) days after which the animals were sacrificed. The blood samples were taken for haematological and biochemical analysis. Antibacterial and antifungal activities of n-hexane, ethyl acetate and methanol extracts of Annona muricata leaves were carried out. These extracts exhibited satisfactory inhibitory activities against bacterial and fungal strains, which include; Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Klebsiellae pneumonae, Candida albicans, Aspergillus niger, penicillium notatum and Rhizopus stolonifer. N-hexane extract of the plant exhibited antioxidant property by scavenging DPPH radicals with IC50 of 342.44 µg/mL. GC-MS analysis of n hexane, ethyl acetate and methanol extracts of the plant principally revealed the presence of Urs-12-ene (23.15%), Squalene (48.80%) and Clionasterol (15.88%) respectively.
- ItemExploring the Binding Interactions of Structurally Diverse dichalcogenoimidodiphosphinate Ligands with α-amylase: Spectroscopic Approach Coupled with Molecular Docking(journal of Biochemistry and Biophysics Reports, 2020) Ajibade, SundayPostprandial hyperglycemia has orchestrated untimely death among diabetic patients over the decades and regulation of α-amylase activity is now becoming a promising management option for type 2 diabetes. The present study investigated the binding interactions of three structurally diverse dichalcogenoimidodiphosphinate ligands with α-amylase to ascertain the affinity of the ligands for α-amylase using spectroscopic and molecular docking methods. The ligands were characterized using 1H and 31P NMR spectroscopy and CHN analysis. Dis elenoimidodiphosphinate ligand (DY300), dithioimidodiphosphinate ligand (DY301), and thio selenoimidodiphosphinate ligand (DY302) quenched the intrinsic fluorescence intensity of α-amylase via a static quenching mechanism with bimolecular quenching constant (Kq) values in the order of x1011 M-1s-1, indicating formation of enzyme-ligand complexes. A binding stoichiometry of n≈1 was observed for α-amylase, with high binding constants (Ka). α-Amylase inhibition was as follow: Acarbose > DY301>DY300>DY302. Values of thermodynamic parameters obtained at temperatures investigated (298, 304 and 310 K) revealed spontaneous complex formation (ΔG<0) between the ligands and α-amylase; the main driving forces were hydrophobic interactions (with DY300, DY301, except DY302). UV–visible spectroscopy and Forster ¨ resonance energy transfer (FRET) affirmed change in enzyme conformation and binding occurrence. Molecular docking revealed ligands interaction with α-amylase via some key catalytic site amino acid residues (Asp197, Glu233 and Asp300). DY301 perhaps showed highest α-amylase inhibition (IC50, 268.11 ± 0.74 μM) due to its moderately high affinity and composition of two sulphide bonds unlike the others. This study might provide theoretical basis for development of novel α-amylase inhibitors from dichalcogenoimidodiphosphinate ligands for management of postprandial hyperglycemia.
- ItemGC-MS Analysis, Antioxidant and Antimicrobial Activities of Extracts from Ficus mucoso Leaves(International Journal of Chemical and Biochemical Sciences, 2017) Ajibade, SundayThe phytochemical screening of n-hexane, ethyl acetate and methanol extracts of Ficus mucoso leaves confirmed the presence of alkaloids, steroids, terpenoids, flavonoids, saponins, anthraquinones, tannins, glycosides, carbohydrates and fats and oils. The ethyl acetate extract of the leaves had minimal antioxidant activity, exhibiting DPPH free radical scavenging property with IC50 of 701.6 μM, using DPPH antioxidant assay. Six bacteria strains namely; Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomona aeruginosa, Salmonella typhii and Klebsiellae pneumonae and four fungal strains namely; Candida albicans, Aspergillus niger, penicillium notatum and Rhizopus stolonifer were tested against the three extracts and they showed good inhibitory activities against the tested strains. Gas chromatography-Mass spectroscopy (GC-MS) characterization of the extracts revealed the presence of sixteen (16), fifteen (15) and fifteen (15) compounds in n-hexane, ethyl acetate and methanol extracts of Ficus mucoso leaves respectively. The principal constituent in the n-hexane extract was phytol with a relative abundance of 29.7% while the main constituents of the ethyl acetate and methanol extracts were phytol acetate and Naphthalene-1,2,3,5,6,7,8,8a-octahydro-1,8a-dimethyl-7-(1-methylethenyl) with relative abundance of 29.1% and 24.48% respectively.
- ItemHarungana madagascariensis Lam ex poir (Hypericaceae) Fruits Oil Extract: Photochemistry and Acute Toxicity Evaluation(International Journal for Pharmaceutical Science and Research, 2017) Ajibade, SundayThis study reports the phytochemistry of the oil obtained from the air-dried non-utilized fruits of H. madagascariensis a plant widely used in folklore medicine. The H. madagascariensis fruits oil (HMO) was obtained by de-fatting the chloroform extract of the air-dried fruits with n-hexane. The n-hexane extract further separated on a normal phase silica column to afford the HMO. The acute toxicity test was done on mice using the Lorke’s method. Selected physico-chemical properties (specific gravity, refractive index, pH, viscosity and saponification value) were evaluated using standard procedures. Characterization of the fatty acids constituents was done using Gas Chromatography-Mass (GC-MS) and Fourier Transform Infra Red (FTIR) spectroscopic techniques. The HMO (reddish oil) had LD50 > 5000 mg/kg; specific gravity = 0.918; refractive index = 1.472; pH: 6.4, Viscosity: 2.252, Saponification value (mg KOH/g): 140.5. GC-MS characterization of the HMO afforded eight fatty acids derivatives (47.93% unsaturated fatty acid and 14.82% saturated fatty acids of the total peak area): palmitic acid methyl ester (7.00%), palmitic acid (2.61%), linoleyl alcohol (1.22%), linoleic acid methyl ester (26.87%), stearic acid methyl ester (4.09%), linoleic acid (12.72%), linoleic acid ethyl ester (7.12%) and behenic acid methyl ester (1.12%). FTIR spectrum showed vibrational frequencies for: OH, C=C, C=O and C-O functional groups. Aside reporting for the first time the phytochemistry of the fruit oil of H. madagascariensis, the presence of the unsaturated fatty acids, the promising LD50 and physico-chemical properties imply application of the HMO in nutraceutics and cosmetology.
- ItemIsoxazole Derivatives: The Search for Anticancer Drugs(Chemical Research Journal, 2017) Ajibade, SundayAbstract Over the last seven years, there has been a continuous interest towards structural modification of isoxazole heterocycle in order to develop anticancer agents. This quest culminated in the syntheses of a large number of compounds and their evaluation against several cancer cell lines. In this paper, emphasis is made on reporting the synthesis and anticancer studies of selected compounds that exhibited a spectacular activity against the different cancer cell lines.
- ItemA novel benzofuro-(2, 3-c)-7′-chromene from Cassia sieberiana(Natural Product Research, Taylor & Francis, 2021) Ajibade, SundayThe stem bark of Cassia sieberiana was extracted with methanol and the methanol extract partitioned with chloroform. Column chromatography of the chloroform fraction over silica gel yielded a novel benzofurochromene [2-(4-hydroxylphenyl)-7’-1, 2-dihy droxy-1-phenylpropyl)-4’, 6’-dihydroxy [1] phenylbenzofuro (2, 3-c)-7’-chromene], lupeol and epiafzelechin. Their structures deter mined by Nuclear Magnetic resonance and mass spectrometry.
- ItemSynthesis, Antimalarial Activity, and Docking Studies of Monocarbonyl Analogues of Curcumin(Ovidius University Annals of Chemistry; 29, 2, 92-96. DOI: 10.2478/auoc-2018-0013, 2018) Ajibade, SundayThe synthesis of five monocarbonyl analogues of curcumin is described. In vitro anti-malarial assay of the compounds was carried out and the effect of the substituents on the aryl ring has been described. The results show that all the five compounds exhibited some reasonable activity against the chloroquine-resistant plasmodium parasite. Molecular docking studies further confirmed the observed biological activity of the compounds.
- ItemThaumatococcus Daniellii Leaves: Its Chemical Compositions, Antioxidant and Antimicrobial Activities(Ife Journal of Science, 2017) Ajibade, SundayThe preliminary phytochemical investigation of n-hexane, ethyl acetate and methanol extracts of aumatococcus daniellii leaves revealed the presence of fats and oils, terpenoids, flavonoids, steroids and glycosides. The antimicrobial tests against some strains of bacteria and fungi showed inhibitions at moderate to high concentrations. Methanol extract of the plant exhibited low 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity with IC of 615.14 µg/ml. Gas chromatography-mass spectrometry (GC-MS) 50 characterization of n-hexane, ethylacetate and methanol extracts of T. daniellii leaves identified , thirteen and fifteen compounds, with tetracontane (28.76%) and L-ascorbic acid (15.07%); hexadecanoic acid (21.62%) and γ-sitosterol (11.06%); and naphthalene-1,2,3,5,6,7,8,8a-octahydro-1,8a-dimethyl-7-(1-methylethenyl)- ,[1R(1.alpha.,7.beta.,8a.alpha.] (26.90%) and hexadecanoic acid (12.60%) being the major compounds respectively. The GC-MS analysis revealed various peaks of bioactive compounds of which the antioxidant and antimicrobial activities of the plant have been attributed to the prominent compounds in synergy with all the other compounds present in smaller quantities in the extracts.