Inhibitory Kinetics of α-Sucrase by 1-Deoxynojirimycin from Mulberry Leaves

As a potent inhibitor of α-glycosidases,1-deoxynojirimycin (DNJ) purified from mulberry leaves has strong antidiabetic activity.In order to elucidate the functional mechanism of mulberry leaf DNJ to α-sucrase,the inhibitory characteristics of mulberry leaf DNJ (purity95%) to α-sucrase was analyzed by means of enzymatic inhibitory kinetics.The establishment of enzymatic reaction system indicated that,when the concentration of α-sucrase was below 500 μg/mL and the reaction time was within 8 min,the reaction system showed good linearity.Inhibition activity assay indicated that the activity of α-sucrase was obviously inhibited by mulberry leaf DNJ and the half inhibitory concentration (IC50) was 5.67 mg/mL.Based on the results of kinetic curves and Lineweaver-Burk plots of mulberry leaf DNJ's inhibition to α-sucrase,the inhibition was of the reversible noncompetitive inhibition pattern and the constant of inhibition (Ki) is 6.73 mg/mL.