TitleGrape seed and tea extracts and catechin 3-gallates are potent inhibitors of α-amylase and α-glucosidase activity.
Publication TypeJournal Article
Year of Publication2012
AuthorsYilmazer-Musa M, Griffith AM, Michels AJ, Schneider E, Frei B
JournalJ Agric Food Chem
Date Published2012 Sep 12
Keywordsalpha-Amylases, alpha-Glucosidases, Camellia sinensis, Catechin, Enzyme Inhibitors, Fungal Proteins, Glycoside Hydrolase Inhibitors, Humans, Kinetics, Plant Extracts, Saccharomycetales, Saliva, Seeds, Vitis

This study evaluated the inhibitory effects of plant-based extracts (grape seed, green tea, and white tea) and their constituent flavan-3-ol monomers (catechins) on α-amylase and α-glucosidase activity, two key glucosidases required for starch digestion in humans. To evaluate the relative potency of extracts and catechins, their concentrations required for 50 and 90% inhibition of enzyme activity were determined and compared to the widely used pharmacological glucosidase inhibitor, acarbose. Maximum enzyme inhibition was used to assess relative inhibitory efficacy. Results showed that grape seed extract strongly inhibited both α-amylase and α-glucosidase activity, with equal and much higher potency, respectively, than acarbose. Whereas tea extracts and catechin 3-gallates were less effective inhibitors of α-amylase, they were potent inhibitors of α-glucosidase. Nongallated catechins were ineffective. The data show that plant extracts containing catechin 3-gallates, in particular epigallocatechin gallate, are potent inhibitors of α-glucosidase activity and suggest that procyanidins in grape seed extract strongly inhibit α-amylase activity.

Alternate JournalJ. Agric. Food Chem.
PubMed ID22697360
PubMed Central IDPMC4356113
Grant ListT32 ES007060 / ES / NIEHS NIH HHS / United States