Curcumin inhibits melanogenesis in human melanocytes

Plant derived compounds, as potentially safe and effective skin lightening agents (SLAs), have attracted great attention from many researchers. Curcumin is a plant-derived polyphenol, which has been reported to suppress melanogenesis in B16 melanoma cells. However, little is known about whether curcumin affects melanogenesis in cultured human melanocytes. In addition, the molecular mechanism for the antimelanogenic effects of curcumin remains largely unknown. The present study assessed the effects of curcumin on melanin synthesis, cellular tyrosinase activity, the expression of melanogenesis-related proteins (microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein 1 and 2 (TRP-1, TRP-2)), and activation of melanogenesis-regulating signals including phosphatidylinositol 3-kinase (PI3K)/Akt/ glycogen synthase kinase 3 (GSK 3β), extracellular signal-regulated kinase (ERK) and p38 MAPK in human melanocytes. The results showed that the melanin content and tyrosinase activity, as well as the expression of melanogenesis-related proteins in human melanocytes, were significantly inhibited by curcumin in a dose dependent manner. In addition, PI3K/Akt/ GSK 3β, ERK and p38 MAPK were activated by curcumin, while inhibitors of these signals attenuated the inhibitory effects of curcumin on melanogenesis. These results suggest that curcumin inhibits melanogenesis in human melanocytes through activation of Akt/GSK 3β, ERK or p38 MAPK signaling pathways.