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

ABSTRACT

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 alpha-amylase and alpha-glucosidase activities in vitro. 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 alpha-amylase and alpha-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. The predominant phenolics detected by GCFID were kaempferol, rutin, apigenin, luteolin, caffeic acid and quercetin. The results showed that all the Corchorus species significantly [P < 0.05] inhibited alpha-amylase and alpha-glucosidase activities dose-dependently [0-8 micro g/ml]. C. olitorius had the highest alpha-amylase inhibitory ability while C. bougoudo demonstrated the maximum alpha-glucosidase inhibition. However, all the Corchorus species inhibited alpha-glucosidase better than alpha-amylase and also exhibited antioxidant properties. 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