Inhibitory Kinetics Study of Resveratrol on Tyrosinase Activity in Vitro

Abstract:

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.