Cypress tree (Chamaecyparis obtusa) Bark extract inhibits melanogenesis through repressing CREB and MITF signalling pathways in α-MSH-stimulated B16F10 cells

ABSTRACT Cypress tree (Chamaecyparis obtusa) bark is well-known for its bio-functional activities and high content of polyphenol and flavonoids. It has previously exhibited antioxidant, anti-pathogenic, and anti-inflammatory activities. Our study aimed to investigate the anti-melanogenic effect of Cypress Tree Bark extract (CBE). We evaluated cellular tyrosinase activity and melanin content in alpha-melanocyte-stimulating hormone (α-MSH) induced B16F10 murine melanoma cells. We analyzed microphthalmia-associated transcription factor (MITF), tyrosinase-related protein (TRP1 and TRP2), and cAMP response element-binding protein (CREB) activation via phosphorylation of AKT and ERK using western blot analysis. Tyrosinase, MITF, TRP1, and TRP2 mRNA expression were examined via real-time polymerase chain reaction. CBE restored melanin content and tyrosinase activity remarkably in α-MSH stimulated melanoma cells. It exhibited an anti-melanogenic effect through suppressing MITF, TRP1, TRP2, tyrosinase mRNA and protein expression in α-MSH-induced B16F10 cells. Furthermore, CBE has significantly inhibited CREB activation by suppressing AKT and extracellular signal-regulated kinase phosphorylation. Our data strongly suggest that CBE has potential effects against melanogenesis. GRAPHICAL ABSTRACT Graphical Abstract: The proposed mechanism of CBE on anti-melanogenic effect.