Tyrosinase activity and melanogenic effects of rhododendron schlippenbachii extract in vivo and in vitro

Abstract

Rhododendron schlippenbachii have been used as a medicine because of their various biological activities. In this study, R. schlippenbachii ethanol extract was evaluated for the treatment of vitiligo. The R. schlippenbachii ethanol extract did not show any cell cytotoxicity. The effect on mushroom tyrosinase and cellular tyrosinase activities were further assessed. In addition, the determination of melanin content in melanocytes was measured using both the B16 melanoma cells and C57BL/6J Ler-vit/vit mice. Finally, the existence of quercetin in R. schlippenbachii was confirmed by qualitative analysis using HPLC. The results clearly demonstrated the R. schlippenbachii extract enhanced melanogenesis and also increased tyrosinase activity in cultured melanoma cells and C57BL/6J Ler-vit/vit mice. In addition, treatment with R. schlippenbachii extract led to a higher content of melanin and eumelanin in C57BL/6J Ler-vit/vit mice hair than in control (untreated) mice, which demonstrated the therapeutic effect of hair-graying associated with vitiligo. Finally, we confirmed a notable increase in melanocytes in the skin of C57BL/6J Ler-vit/vit mice treated with R. schlippenbachii extract compared with the control. Extracts of R. schlippenbachii was shown to be potent tyrosinase and melanin synthesis activator in B16 melanoma cells. The R. schlippenbachii extract have significantly higher melanin content than the untreated control in C57BL/6J Ler-vit/vit mice hair. The results suggest that R. schlippenbachii extract might be considered as an alternative treatment for improvement of vitiligo.