Objective: To observe the effect of Xiaochaihu Tang on the mRNA expression levels of melanogenesis related genes

including tyrosinase (TYR)

tyrosinase related protein-1 (TRP-1) and tyrosinase related protein-2 (TRP-2) in B16 melanoma cells. Method: CCK8 assay was used to test the cell activity

and low dose

middle dose and high dose Xiaochaihu Tang (0.1

1

2.5 g · L-1) were used in the test. Reverse transcription-polymerase chain reaction(RT-PCR) was applied to measure the mRNA expression levels of TYR

TRP-1 and TRP-2. Result: Compared with the blank group

Xiaochaihu Tang can significantly down-regulate the mRNA expression levels of TYR

TRP-1 and TRP-2 with the increase of concentrations (P<0.05

P<0.01). Conclusion: Xiaochaihu Tang could significantly suppress melanogenesis not only by inhibiting TYR activity

but also by down-regulating the gene expression of TRP-1 and TRP-2 as well as protein synthesis

indicating that Xiaochaihu Tang could inhibit melanogenesis by regulating pathways after enzyme protein transcription.