Abstract: Objective To develop an in vitro method to determine the effects of drugs on tyrosinase(TYR)activity and screen the inhibitory effects on TYR of 14 extracted components of Chinese medicinal herbs.Methods The activity of TYR was detected by revised Matsuda's method.Effects of14extracted components on tyrosinase system were observed in vitro.Results Ten of the 14 components showed dose-dependent down-regulation of tyrosinase activity and melanogenesis.The inhibitory activities of eugenol,curcumin and gallic acid were significantly higher than those of arbutin(P<0.05).The combinations of eugenol and curcumin(1:1),and eugenol,curcumin and ecdysone(1:1:1)had significantly higher inhibitory activities as compared to those of arbutin(P<0.05).It was indicated that eugenol and curcumin acted as competitive inhibitors while gallic acid as an opposite competitive inhibitor.Conclusion Eugenol,curcumin,gallic acid and other effective components of traditional Chinese medicines can inhibit TYR in vitro.

Key words: Monophenol monooxygenase, Eugenol, Curcumin, Gallic acid, Ecdysone, Drugs,Chinese herbal