Soft corals collected from Jeju Island inhibits the α-MSH-induced melanogenesis in B16F10 cells through activation of ERK

In the present study, we first evaluated the melanin inhibitory effect of four crude 70% ethanol extracts separated from soft corals abundantly growing along the seawaters of Jeju Island, South Korea, including Dendronephthya castanea (DC), Dendronephthya gigantea (DG), Dendronephthya puetteri (DP), and Dendronephthya spinulosa (DS). Among the four ethanol extracts, the ethanol extract of DP (DPE) did not possess any cytotoxic effect on B16F10 cells. However, all other three extracts showed a cytotoxic effect. Also, DPE reduced the melanin content and the cellular tyrosinase activity without cytotoxicity, compared to the α-MSH-stimulated B16F10 cells. Specifically, DPE downregulated the expression levels of tyrosinase and microphthalmia-associated transcription factor by activating the ERK signaling cascade in α-MSH-stimulated B16F10 cells. Interestingly, the melanin inhibitory effect of DPE was abolished by the co-treatment of PD98059, an ERK inhibitor. According to these results, we suggest that DPE has whitening capacity with the melanin inhibitory effects by activating ERK signaling and could be used as a potential natural melanin inhibitor for cosmeceutical products. Molecular mechanisms associated with melanin inhibitory effect of soft coral extracts against α-MSH induced B16F10 cells