Inhibitory Effects Of 6,6 '-Bieckol From Ishige Okamurae On Tyrosinase Activity And Melanin Synthesis In Mouse B16f10 Melanoma Cells

In this study, two phlorotannins such as 6,6'-bieckol and diphlorethohy-droxycarmalol were isolated from Ishige okamurae (Phaeophyta) and screened for their inhibitory effect on tyrosinase activity in vitro. Between them, 6,6'-bieckol has shown potent tyrosinase inhibitory effect (IC50 = 1.36 mu M) and Lineweaver-Burk plots suggest that 6,6'-bieckol acts as a non-competitive inhibitor. Moreover, the effect of 6,6'-bieckol on a-melanocyte stimulatory hormone (alpha-MSH) induced cellular melanin content and expressions of tyrosinase, TRP-1, TRP-2 and microphthalmia-associated transcription factor (MITF) in mouse melanoma B16F10 cells. According to the Western blot and RTPCR studies, it was revealed that 6,6'-bieckol down-regulates the expressions of tyrosinase, tyrosinase related protein-1 (TRP-1), tyrosinase related prgtein-2. (TRP-2) and MITF in mouse melanoma cells in a dose-dependent manner. Collectively, these results suggest that 6,6'-bieckol could be used as a novel inhibitor of melanin formation in cosmetic applications.