Inhibitory mechanism of novel allosteric inhibitor, Chinese bayberry (Myrica rubra Sieb. et Zucc.) leaves proanthocyanidins against α-glucosidase

α-Glucosidase is a key enzyme related to starch digestion and type-2 diabetes. In the present study, the inhibition effect and the underlying mechanism of Chinese bayberry leaves proanthocyanidins (BLPs) on α-glucosidase were investigated by enzyme kinetic analysis, multi-spectroscopy and molecular docking simulation. The results revealed that BLPs was a high potential noncompetitive-type inhibitor of α-glucosidase with the half maximal inhibitory concertation (IC50) value of 0.037 ± 0.001 mg mL −1 and acarbose equivalent (AE) of 517.01 mmol AE g −1 . What’s more, BLPs may interact with some amino acids surrounded in the allosteric site of α-glucosidase to form a complex driven by hydrogen bonding and hydrophobic interaction, and thus change the structure and microenvironment of α-glucosidase, leading to the decrease of activity of α-glucosidase. The present study suggested that BLPs as epigallocatechin-3-O-gallate (EGCG) polymers could be a novel α-glucosidase inhibitor and had potential to be further used in functional food or anti-diabetic drug.