Inhibitory Effect of Belamcandae Rhizoma on the Melanogenesis in MSH-stimulated B16F10 cells

Abstract

Objective : The present study was designed to assess the potential inhibitory activity of an ethanol extract of Belamcandae Rhizoma (EBR) on the alpha-melanocyte stimulating hormone (α-MSH)-induced melanogenesis signal pathway in B16F10 melanoma cells. Methods : Several experiments were performed in B16F10 melanoma cells. We studied tyrosinase activity, melanin content, cell-free tyrosinase activity and DOPA stain, and performed Western blots and RT-PCR for proteins and mRNA involved in melanogenesis. Results : α-MSH-induced tyrosinase activity and melanin content were inhibited significantly by EBR. EBR markedly suppressed the protein expression level of tyrosinase in B16F10 melanoma cells. On the other hand, the expression of tyrosinase-related protein-1 (TRP-1) and -2 (TRP-2; DCT) were not affected by EBR. To elucidate the mechanism of the depigmenting property of EBR, we examined the involvement EBR in cAMP response element binding (CREB) protein phosphorylation and microphthalmia-associated transcription factor (MITF) signalling induced by α-MSH. EBR did not regulate CREB phosphorylation and MITF expression by α-MSH. Nevertheless, the mRNA expression of tyrosinase was significantly attenuated by EBR treatment without changes in the expression of TRP-1 and -2 mRNA. Conclusion : Our study suggested that EBR inhibits α-MSH-induced melanogenesis by suppressing tyrosinase mRNA.Key words : Belamcandae Rhizoma, melanin, tyrosinase, α-MSH