Inhibitory effect and mechanism of tannic acid against two starch digestive enzymes

Backgrounds:Tannic acid(TA),as a plant-derived phenolic substance,is involved in regulating the activity of starch digestive enzymes,but its underlying mechanism remains unclear.Methods and Results:In the present study,inhibition rate and inhibition kinetics assays were performed and confrmed that TA had a strong inhibitory effect on bothα-amylase andα-glucosidase with IC50 values of 0.1585 mg/mL and 0.00542 mg/mL,respectively,through a mixed inhibition mode.The secondary structures of both enzymes were confrmed to be modifed by TA through circular dichroism(CD)spectra.Fluorescence quenching analysis revealed that the interaction between TA and two enzymes was a static process of pontaneous complex formation.Finally,molecular docking revealed that non-covalent bonds were the main interaction forces between TA and both enzymes.Conclusions:Thus,TA was a promising candidate for the inhibition of starch-digesting enzymes,and the present research provided insight into postprandial glucose regulation through polyphenols.