Sesquiterpenoids from Seriphidium transiliense and Their Melanogenic Activity

A sesquiterpenoid with an unprecedented 5/5/4 tricyclic skeleton (1), a nor-sesquiterpenoid with a rare 6/7 bicyclic skeleton (2), 10 new sesquiterpenoids (3–12), and six known analogues (13–18) were isolated from the whole plants of Seriphidium transiliense. The structures of compounds 1–12 were elucidated by spectroscopic data analysis. Compound 7 showed melanogenic promotion activity in murine melanoma (B16) cells more potent than the positive control used, 8-methoxypsoralen (8-MOP). Further mechanistic studies indicated that compound 7 promotes melanogenesis through activating the transcription of microphthalmia-associated transcription factor (MITF) and tyrosinase family genes in B16 cells. Moreover, compound 7 also inhibited the expression of IFN-γ-chemokine through the JAK/STAT signaling pathway in immortalized human keratinocyte (HaCaT) cells. These results suggest that the sesquiterpenoid 7 shows potential activity for treating vitiligo.