Inhibitory effect of CADI on melanin transfer in the B16F10-HaCAT cells co-culture system and anti-melanogenesis of CNCE in zebrafish

Skin pigmentation depends not only on melanosomes produced by melanocytes but also on the migration of melanosomes to adjacent keratinocytes and their distribution on the skin surface. The inhibitory effects of cardanol diene (CADI), a major phenolic compound extracted from cashew nut shell liquid (CNSL), on melanin transfer in B16F10-HaCAT co-culture cells and a crude extracted compound of cashew nut shell oil (CNCE) on melanin production in zebrafish were investigated. β-arbutin was used as a positive control. CADI inhibited the expression levels of the melanin phagocytosis-associated protein PAR-2 and filopodia-associated protein NMDAR1, and the effect was better than that of β-arbutin at the same concentration. To further study the inhibitory mechanism of CADI in melanin transfer, fluorescence microspheres were used to simulate melanin and co-culture with keratinocytes. The results indicated that CADI inhibited melanin transfer through suppressing keratinocyte phagocytosis, dendrite formation and filopodia three channels. We also found that CNCE inhibited melanin production in zebrafish and showed significant inhibitory effects on TYR, DCT and α-MSH. Thus, the natural components extracted from CNSL effectively inhibited skin pigmentation, providing insight into the application of new anti-melanin drugs in cosmetics and medicine.