Inhibitory Kinetics Study of Resveratrol on Tyrosinase Activity in Vitro

The inhibitory effect of resveratrol on the activity of monophenolase and diphenolase existing in tyrosinase was investigated by the enzymatic kinetic method at 30 ℃ in a Na2HPO4-NaH2PO4 buffer system(pH6.8).The results indicated that resveratrol could inhibit both the monophenolase and diphenolase activities of tyrosinase,and the IC50 values(resveratrol concentration corresponding to 50% inhibitory rate) were 5.1 mg/mL and 5.6 mg/mL,respectively.Furthermore,resveratrol could extent the lag time of monophenolase for oxidation of L-tyrosine,of which 8 mg/mL of resveratrol prolonged the lag time from 22 s to 62 s,while no such effect was observed on diphenolase.According to the Lineweaver-Burk plot,resveratrol was found to be a mixed inhibitor for the oxidation of L-DOPA,and the equilibrium constants for binding with free enzyme KI and with enzyme-substrate complex KIS were 3.4 mg/mL and 35.98 mg/mL,respectively.