Computational prediction integrating the inhibition kinetics of gallotannin on α-glucosidase

Due to the finding that inhibition of α-glucosidase is directly associated with treatment of several diseases, the development of a selective inhibitor for targeting α-glucosidase is important. Gallotannin (GT) is a natural ingredient that has been used as a food additive and for medicinal applications. In this study, we performed a computational docking experiment involving the pre-simulation of the binding mechanism of GT, and the effect of GT on α-glucosidase was evaluated with inhibitory kinetics based on its polyphenol properties. The computational simulations indicated that the hydroxyl groups of GT interact with several residues near the α-glucosidase active site (Met69, Tyr71, Phe177, Arg212, Asp214, Glu276, His348, Asp349, and Arg439), which could affect the catalytic function of α-glucosidase by retarding substrate access. Subsequent kinetic experiments showed that GT conspicuously inhibited α-glucosidase in a parabolic mixed-type manner (IC50 = 1.31 ± 0.03 μM; Ki = 0.41 ± 0.032 μM). Our study provides insight into the inhibition mechanism and binding manner of GT to α-glucosidase. Based on its α-glucosidase-inhibiting effect and its demonstrated safety as a naturally derived compound, GT represents a promising potential agent for treatment of α-glucosidase-associated diseases.