Abstract: Objective To investigate the effect of traditional Chinese medicine(TCM) on tyrosinase activity and provide experimental evidence for treating melasma. Methods Tyrosinase activity was measured by the rate of oxidation of DL-dopa. Results Tyrosinase activity decreased in groups of patients with Decoction of Six Drugs Including Rehmannia(Liuwei Dihuang Wan), Decoction for Reinforcing Middle jiao(Buzhong Yiqi Tang) (water extract P<0.05, ethanol extract P>0.05), increased in groups of patients with Modified Ease Pill(Xiaoyao Wan),Decoction of Four Ingredients plus Peach Kernel and Safflower(Taohong Siwu Tang)(P<0.01) and decreased in groups of patients with Bolus for Tonifying the Kidney-qi(Jingui Shunqi Wan).While determined in single component TCM of Liuwei Dihuang Wan, tyrosinase activity increased in groups of patients with water extract of Radix Rehmanniae Praeparatae, Cortex Moutan, decreased in Poria, Rhizoma Dioscoreae, Fructus Corni;and increased in groups of patients with ethanol extract of Cortex Moutan,Rhizoma Alismatis, and decreased in Poria, Rhizoma Dioscoreae, Fructus Corni. Conclusions Tyrosinase activity can be reduced by the treatment of Liuwei Dihuang Wan ,Buzhong Yiqi Tang, Poria, Rhizoma Dioscoreae, Fructus Corni;and increased by the treatment of Radix Rehmanniae, Cortex Moutan. Tyrosinase activity increases in ethanol extract and decreases in water extract of Rhizoma Alismatis.

Key words: Melanosis, Composite(TCD), Monophenol monooxygenase