Antioxidant properties and in vitro α-amylase and α-glucosidase inhibitory properties of phenolics constituents from different varieties of Corchorus spp.

Objectives This study investigated the phenolic constituents, antioxidant properties and effect of aqueous extracts from some Corchorus species (C. aestuans, C. bougoudo, C. capsularis, C. olitorius and C. urtifolicus) on α-amylase and α-glucosidase activities in vitro. Methods Gas Chromatography with Flame Ionization Detector (GC-FID) was used to characterize the phenolic constituents. Aqueous extracts were prepared weight/volume (w/v) and their effects on α-amylase and α-glucosidase activities, Fe 2+ induced lipid peroxidation , and 1,1-diphenyl-2 picrylhydrazyl (DPPH) radical scavenging properties were determined. Fe 2+ chelating abilities and Ferric Reducing Antioxidant Power (FRAP) properties were also studied. Results The predominant phenolics detected by GC-FID were kaempferol , rutin , apigenin , luteolin , caffeic acid and quercetin . The results showed that all the Corchorus species significantly (P < 0.05) inhibited α-amylase and α-glucosidase activities dose-dependently (0–8 μg/ml). C. olitorius had the highest α-amylase inhibitory ability while C. bougoudo demonstrated the maximum α-glucosidase inhibition. However, all the Corchorus species inhibited α-glucosidase better than α-amylase and also exhibited antioxidant properties. Conclusions The enzyme inhibitory and antioxidant properties exhibited by the Corchorus species could be attributed to their phenolic constituents and vitamin C content; a possible mechanism by which Corchorus species could elicit therapeutic effects on type 2 diabetes mellitus as obtained in folklore medicine.