α-Glucosidase inhibitory effect of resveratrol and piceatannol

Dietary polyphenols have been shown to inhibit alpha-glucosidase, an enzyme target of some antidiabetic drugs. Resveratrol, a polyphenol found in grapes and wine, has been reported to inhibit the activity of yeast alpha-glucosidase. This triggered our interest to synthesize analogs and determine their effect on mammalian alpha-glucosidase activity. Using either sucrose or maltose as substrate resveratrol, piceatannol and 3 '-hydroxypterostilbene showed strong inhibition of mammalian alpha-glucosidase activity; pinostilbene, cis-desoxyrhapontigenin and trans-desoxyrhapontigenin had moderate inhibition. Compared to acarbose (IC50 3-13 mu g/ml), piceatannol and resveratrol inhibited mammalian alpha-glucosidase to a lesser extent (IC50 14-84 and 111-120 mu g/ml, respectively). 3 '-Hydroxypterostilbene (IC50 105-302 mu g/ml) was 23-35-fold less potent than acarbose. We investigated the effect of piceatannol and resveratrol on postprandial blood glucose response in high-fat-fed C57BI/6 mice. Animals administered resveratrol (30 mg/kg body weight [BW]) or piceatannol (14 mg/kg BW) 60 min prior to sucrose or starch loading had a delayed absorption of carbohydrates, resulting in significant lowering of postprandial blood glucose concentrations, similar to the antidiabetic drug acarbose, while no significant effect was observed with the glucose-loaded animals. Our studies demonstrate that the dietary polyphenols resveratrol and piceatannol lower postprandial hyperglycemia and indicate that inhibition of intestinal alpha-glucosidase activity may be a potential mechanism contributing to their antidiabetic property. (C) 2017 Elsevier Inc. All rights reserved.