Alpha-Amylase Inhibitory and Antioxidant Activities in Aqueous Acetone Extract and its Fractions from Ampelocissus martini Root

This study aimed to evaluate and correlate phytochemical content, antioxidant activity and alpha-amylase inhibitory activity in aqueous acetone extract and fractions derived from it (ethyl acetate fraction, watersoluble fraction, aqueous methanol fraction and aqueous acetone fraction) which are obtained from Ampelocissus martini Planch. root. Ethyl acetate fraction and aqueous acetone fraction had the highest total phenolic content and total proanthocyanidin content, respectively. 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid), cupric reducing antioxidant capacity and ferric reducing antioxidant power assays showed that aqueous acetone fraction had higher antioxidant activity compared to other samples and standards. Acarbose and all samples except aqueous methanol fraction inhibited alpha-amylase, a key enzyme linked to type 2 diabetes, in a dose-dependent manner and aqueous acetone fraction showed the strongest inhibition (half-maximal inhibitory concentration=8.77 +/- 0.28 mu g/ml). Aqueous acetone fraction was a mixed noncompetitive inhibitor of the enzyme. Correlation analysis showed strong positive correlations among proanthocyanidin content, antioxidant activity and alphaamylase inhibitory activity. These results suggest that aqueous acetone fraction, proanthocyanidins-rich fraction from Ampelocissus martini root, may be used for effective diabetes management because of its high potential antioxidant activity and alpha-amylase inhibitory activity.