Abstract

The study investigated the antioxidant potential as well as the inhibitory potential of the seed extracts of Picralima nitida on α-amylase and α-glucosidase enzymes. The methanolic, aqueous and coconut water extracts were obtained using 70% methanol, distilled water and coconut water, respectively. Antioxidant properties were studied in vitro using DPPH (1, 1-diphenyl-2-pricrylhydrazyl) radical scavenging, Ferric Reducing Antioxidant Power (FRAP), Total Antioxidant Capacity (TAC), Hydroxyl Radical Averting Capacity (HORAC), Total Phenol Content (TPC), and Total Flavonoid Content (TFC) assays. Different concentrations (0.1 - 0.5 mg/ml) of the extracts were subjected to α-amylase and α-glucosidase inhibitory assays using acarbose as standard. Absorbance was measured at 540 (for α-amylase) and 405 nm (α-glucosidase). The percentage of α-amylase and α-glucosidase inhibitory activity of the extracts and their IC50 values were determined. The seed extracts of P. nitida showed significant antioxidant potential. The inhibitory activity of the extracts on α-amylase and α-glucosidas compared favourably with acarbose with the methanolic extract possessing the highest inhibitory activity. The methanolic extract also possessed the highest antioxidant capacity with the lowest IC50 value among the extracts. The results indicate that the seed extracts of P. nitida possess significant antioxidant properties and are effective inhibitors of α-amylase and α-glucosidase enzymes.

Key words: Antioxidants, α-amylase, α-glucosidase, diabetes, phenolics, flavonoids, Picralima nitida.