Antioxidant and α-Glucosidase Inhibitory Activities of Phenolic Compounds Isolated from the Aerial Parts of Ampelocissus africanus
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Date
2021
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Natural Product Research Group, Department of Pharmaceutical Chemistry Faculty of Pharmacy, University of Benin, Nigeria.
Abstract
Ampelocissus africanus is an important medicinal plant with diverse ethnomedicinal uses. The purpose of this study was to investigate the antioxidant and α-glucosidase inhibitory activities of phenolic compounds isolated from the aerial parts of Ampelocissus africanus.Two known compounds were isolated using a combination ofcolumn and thin layer chromatography. The structures were elucidated usingUV and NMR spectroscopy. The antioxidant activity of the compounds was evaluated using 2,21-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays, while the antidiabetic potential was investigated using the α-glucosidase inhibition assay. Ascorbic acid and acarbose were used as standard and data obtained were expressed as mean ± SEM.The IC50 of the two compounds were calculated using a suitable regression analysis and graph pad prism software 6.0 using t-test.Compounds 1 and 2 were isolated as a yellow solids and identified as methyl gallate and quercetin, respectively. Result of the antioxidant assay using ABTS revealed that compound 1 gave a percentage inhibition of 98.22±0.79, while compound 2 gave 99.04±0.39% inhibition. The DPPH assay revealed inhibition at 59.38±3.23% and 63.45±2.56% for compounds I and 2, respectively. The values for DPPH assay were significantly different at p value <0.05 when compared to ascorbic acid. Compound 2 exhibited α-glucosidase inhibitory activity (IC50 4.02±0.37 μg/mL) though lower than acarbose (IC50 0.98± 0.57 μg/mL). Compound 1 however, showed weak α-glucosidase inhibitory activity with IC50>100μg/mL. These results might justify the ethnomedicinal uses of this plant in ameliorating metabolic disorder such as diabetes.