Docosahexaenoic acid inhibits melanin synthesis in murine melanoma cells in vitro through increasing tyrosinase degradation.

AIM: To investigate the effects of docosahexaenoic acid (DHA) on melanin synthesis and related regulatory mechanisms. METHODS: B16F10 mouse melanoma cells were exposed to DHA for 3 d, and melanin content and tyrosinase activity were measured. Western blot analysis was used to analyze the protein levels in DHA-mediated signal transduction pathways. RESULTS: DHA (1-25 μmol/L) did not affect the viability of B16F10 cells, but decreased α-MSH-induced melanin synthesis in a concentration-dependent manner. DHA concentration-dependently reduced tyrosinase activity in the cells, but did not affect mushroom tyrosinase activity in a cell-free system. Furthermore, DHA treatment significantly reduced tyrosinase level without affecting microphthalmia-associated transcription factor (MITF) in the cells. DHA did not activate ERK and Akt in the cells. Pretreatment with the proteasome inhibitor MG132 (80 nmol/L) abolished DHA-induced tyrosinase reduction. CONCLUSION: DHA inhibits melanogenesis in B16F10 cells in vitro through increasing tyrosinase degradation. The results suggest that DHA may be a potential agent for treatment of hyperpigmentary disorders of skin.