Hyperpigmentation mechanism of methyl 3,5-di-caffeoylquinate through activation of p38 and MITF induction of tyrosinase

Methyl 3,5-di-caffeoylquinate (3,5-diCQM) has been used for the treatment of various diseases in oriental medicine, but its effect on melanogenesis has not been reported yet. In this study, the molecular mechanism of 3,5-diCQM-induced melanogenesis was investigated. It was found that 3,5diCQM induced synthesis of melanin pigments in murine B16F10 melanoma cells in a concentrationdependent manner. Treatmentofcells with 3,5-diCQM for 48 h increased extracellularand intracellular melanin production and tyrosinase activity. The expressions of tyrosinase, tyrosinase-related protein 1 (TRP1), and TRP2 were up-regulated in a dose-dependent manner 48 h after 3,5-diCQM treatment. Western blot analysis showed that 3,5-diCQM increased the phosphorylation of p38 mitogen-activated protein kinase and cAMP responsive element binding as well as the expression of microphthalmiaassociated transcription factor. In addition, 3,5-diCQM-stimulated cAMP production, and 3,5-diCQMinducedtyrosinase activityandmelanin synthesiswere attenuated byH89,a protein kinase A inhibitor. These resultssuggestedthat3,5-diCQM-mediatedactivationofthe p38 pathway may represent anovel approach for an effective therapy for vitiligo and hair graying.