Inhibitory Effect of Koji Aspergillus terreus on α-Glucosidase Activity and Postprandial Hyperglycemia

The compounds that could inhibit the activity of a-glucosidase are potentially used for antidiabetic by suppressing postprandial hyperglycemia. This research aimed to investigate the hypoglycemic activity in A. terreus koji extracted by ethyl acetate. The extracts was dissolved in methanol: water (1:4), followed by fractionations with n-hexane, methylene chloride and ethyl acetate. Each fraction was assayed for its activity against a-glucosidase. The active fraction was purified by column chromatography using silica gel and resin as adsorbent. The kopi extract showed potential as alpha-glucosidase inhibition with IC50 <10 microg mL(-1) and showed combination of non-competitive and uncompetitive inhibition mode against a-glucosidase. Ethyl acetate fraction showed potential as inhibitor alpha-glucosidase with IC50 = 8.6 microg mL(-1). In animal experiment, active fraction (F10-4) of ethyl acetate fraction suppressed the increase of postprandial blood glucosidase level compare to the control. Thus it showed potential as alpha-glucosidase inhibitor and demonstrated depressed postprandial blood glucose level and may have potential use in the management of type 2 diabetes.