Oleanolic Acid from Fragaria ananassa calyx Leads to Inhibition of α-MSH-induced Melanogenesis in B16-F10 Melanoma Cells

Natural products with non-toxic and environmentally friendly properties are good sources for skin-whitening and brightening cosmetic agents. Strawberries (Fragaria ananassa), and their parts are used as cosmetic agents, because they contain high levels of bioactive substances. We isolated and identified compounds from F. ananassa calyx. Oleanolic acid has multiple biological activities, including anti-tumor, anti-angiogenic, anti-inflammatory, anti-oxidant, and pro-apoptotic effects. However, no study has investigated the influence of oleanolic acid on melanin synthesis in B16-F10 melanoma cells. In the present study, we investigated the effect of oleanolic acid on melanin biosynthesis in B16-F10 melanoma cells stimulated with alpha-melanocyte stimulating hormone (alpha-MSH). Oleanolic acid-mediated melanogenesis inhibition was studied by measuring intracellular and secreted melanin levels and by using Western blot and semi-quantitative reverse transcriptase-polymerase chain reaction analyses. Oleanolic acid suppressed melanin release and expression, resulting in a significant dose-dependent decrease in secreted and intracellular melanin levels and cellular tyrosinase activity. Furthermore, it inhibited the expression of melanogenesis-associated factors, including tyrosinase, tyrosinase-related proteins-1 and -2, and microphthalmia-associated transcription factor, in alpha-MSH-stimulated B16-F10 melanoma cells. The results of the present study can contribute to the development of cosmetic agents utilizing the skin whitening and brightening effect of oleanolic acid, which will likely have a wide range of applications in the cosmetic industry and/or clinical practice in the future.