Inhibitory effects of apple polyphenol extracts on α-amylase and α-glucosidase

Abstract：The phenolic compounds in apple polyphenol extracts were analyzed by high performance liquid chromatography（HPLC）,and the inhibitory effects of apple polyphenol extracts on the activity of α-amylase and α-glucosidase were examined by using starch and PNPG as substrate respectively.Several phenolic compounds,including gallic acid,protocatechuic acid,catechin,chlorogenic acid,epicatechin,lutin and phlorizin,could be detected in the apple polyphenol extracts.In addition,the results indicated that the apple polyphenol extracts exhibited certain inhibitory effect on α-amylase with an IC50 value of 1.48 g·L-1,and the maximum inhibitition percentage was 88.01% in the range of test concentrations from 0.071 to 5.357 g·L-1.Besides,the apple polyphenol extracts were also a potent α-glucosidase inhibitor with an inhibitory rate of 96.62% at concentration of 2.35 mg·L-1 and an IC50 of 0.72 mg·L-1.The kinetic analysis showed that the inhibition of apple polyphenol extracts on α-amylase was competitive,and the inhibition on α-glucosidase was noncompetitive.