Bieckol isolated from Ecklonia stolonifera inhibits melanin synthesis in B16 melanoma cells.

Abstract

Abstract

Melanin has major roles in skin and pigmented epithelium of the retina. Melanin plays a role in protection against DNA damages and photo-carcinogenesis caused by exposure of the solar-radiation in human skin. Although, melanin is excellent photo-protectant to prevent the DNA damages by UV-radiation, mis-regulation of production and accumulation of melanin is leads to hyper-pigmentation in skin. Melanin is synthesized in the melanosomes of melanocytes and, regulated by melanogeninc enzymes, such as tyrosinase, tyrosinase related protein-1 (TRP-1), and tyrosinase related protein-2 (TRP-2). In this study, the inhibitory effects of the biekol isolated from E. stolonifera on α-MSH-stimulated melanogenesis in cultured B16 mouse melanoma cells were investigated. Biekol had no inhibitory cytotoxicity on B16 cells up to 10 μM and intracellular tyrosinase activity was suppressed by bieckol treatment with dose-dependent manner. In Western blotting analysis, biekol inhibited the expression of tyrosinase, TRP-1, and TRP-2 in α-MSH-stimulated cells with a dose-dependent manner. Furthermore, in RT-PCR experiments, the mRNA expressions of TRP-1, TRP-2 and MITF were significantly reduced by biekol treatment with dose-dependent manner. Bieckol treatment with 5 μM delayed the phosphorylation of Akt and ERK which are responsible to the degradation of MITF. In this result, the hypopigmentary effect of biekol isolated from E. stolonifera resulted from the inhibition of the expression of tyrosinase, TRP-1, and TRP-2 via down-regulation of MITF through phosphorylation of Akt and ERK. Bieckol may provide a beneficial effect for inhibiting melanogenesis and it has a potential for the development of functional cosmetics for whitening effects.