Abstract

This study sought to investigate the inhibitory effect of methanolic extract of different species of African eggplant (Solanum melongena L.) and (Solanum macrocarpon) on starch hydrolysing enzymes relevant to type-2 diabetes (α-amylase and α-glucosidase). The phenolic content and antioxidant properties of the eggplant varieties were also assessed. The results revealed that both extracts exhibited mild α-amylase and stronger α-glucosidase inhibitory activities in a dose dependent manner. Furthermore, S. macrocarpon exhibited stronger radicals (1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging ability, nitric-oxide (NO·) scavenging ability and ferric reducing antioxidant property (FRAP) than S. melongena, while S. melongena had stronger hydroxyl (OH·) radical ability. The inhibition of starch hydrolysing enzymes and antioxidant activities suggested the potential use of eggplants in the dietary management or control of postprandial hyperglycemia associated with type-2 diabetes.

Key words: Antioxidant activity, diabetes, α-amylase, α-glucosidase, Solanum macrocarpon,Solanum melongena.