2, 3, 5, 4′-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) induces melanogenesis in B16 cells by MAP kinase activation and tyrosinase upregulation

Aims: The 2, 3, 5, 4'-tetrahydroxystilbene-2-O-beta-D-glucoside (THSG), a water-soluble active component extracted from dried tuber root of Polygonum multiflorum, has been found to induce pigmentation in B16 cells, but the details of the underlying mechanism remain unknown. The present study was conducted to investigate the mechanism of stimulatory effect of THSG on melanogenesis using B16F1 melanoma cells. Main methods: Several experiments were performed in B16F1 melanoma cells. We studied melanin content, tyrosinase activity, cell viability, and performed reverse transcription polymerase chain reaction and Western blots for proteins involved in melanogenesis. Key findings: THSG increased the melanin content and tyrosinase activity in a concentration-dependent manner and treatment with 10 mu g/ml THSG enhanced the expression of tyrosinase time-dependently in B16 cells. We then investigated whether THSG influences the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. THSG was found to induce sustained MITF up-regulation and cAMP response element (CRE) binding protein (CREB) activation, suggesting that THSG-mediated MITF activation may be cAMP dependent. Furthermore, Western blot analysis revealed that THSG elevated the level of phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) significantly at 1-6 h: a p38 MAPK inhibitor, SB203580, almost completely attenuated the THSG-mediated up-regulation of melanin synthesis and induction of MITF and tyrosinase expression. Significance: THSG exerts its stimulatory effect on melanogenesis by MAP kinase activation and MITF-induction of tyrosinase. (C) 2009 Published by Elsevier Inc.