Development and Application of a High-Throughput Assay for Discovery of Starch Hydrolase Inhibitors

Abstract

For in vitro diabetes assay, to search for the active ingredients in low Glycemic Index foods, a 96-well based high-throughput method (HTS) for rapidly measuring the inhibition of starch hydrolase was developed, by monitoring the decrease in turbidity over time during the enzymatic digestion of starch. By applying HTS, extracts of wild buckwheat root exhibited strong starch hydrolase inhibitory activity, and diboside A was isolated as a selective inhibitor of pancreatic a-amylase and sucrase. Moreover, proanthocyanidins in the extracts of root were also found to be major contributors to the inhibition of starch hydrolase. Phenylpropanoid sucrose ester compounds, smilaside A and smilaside D were isolated from extracts of the Smilax glabra rhizome. Both compounds displayed negligible inhibitory effects towards porcine pancreas a-amylase, but weak and moderate inhibitory activity towards rat intestinal a-glucosidase. The use of grape seeds extracts as a-amylase inhibitors using wheat noodles as the food matrix was investigated.