Inhibitory Effect of Naringin on α-Glucosidase and Its Mechanism

To investigate the inhibitory activity and mechanism of naringin on α-glucosidase, the inhibition effect, type, and molecular mechanism of naringin on α-glucosidase were investigated by integrative analysis of enzyme kinetics, fluorescence spectroscopy and molecular docking simulation. The results showed that IC50 of naringin against α-glucosidase was 0.174 mmol/L, which was significantly lower than that of acarbose (IC50=0.721 mmol/L). The inhibition type was non-competitive inhibition with a Ki of 0.114 mmol/L. The binding of naringin and α-glucosidase led to the internal fluorescence quenching of the enzyme molecule. Furhter analysis indicated that the quenching constant was 0.1598×104 L/mol, and there was only one binding site. The molecular docking results showed that naringin was bound to a hydrophobic pocket of α-glucoside enzyme by the driving force of hydrogen bond, ionic bond, hydrophobic action, π-π-T stacking, and electrostatic action, with a binding energy of −7.6 kJ/mol. The results indicated that naringin was a good food-borne α-glucosidase inhibitor, and therefore had a good application prospect in the adjuvant treatment of diabetes functional food.