Despite Polygonum multiflorum (PM) has been experiencely used as a drug to treat early graying hair phenomenon in Asian countries for a long time, there is limited study examined the real biological effects of PM on hair graying in vitro and in vivo. In this study, we investigated the effects of PM root extract (PM-RE) on melanin synthesis in human melanoma SKMEL-28 cells and embryos/larvae of wild-type strain AB zebrafish. We also preliminary revealed the molecular mechanism of early hair graying phenomenon in both in vitro and in vivo models. Our results showed that PM-RE significantly induced melanin synthesis in melanin-producing SKMEL-28 melanoma cells and also in zebrafish embryos/larvae at 4-day postfertilization through activation of MC1R/MITF/tyrosinase-signaling pathway. We also investigated the differences in genotype between graying hair follicle and black hair follicle of young peoples and found that early hair graying phenomenon may be related to downregulation of MC1R/MITF/tyrosinase pathway. Taken together, we suggested that PM-RE at safe doses could be used as a potential agent for the treatment of early hair graying and other loss pigmentation-related diseases.
Keywords: Graying hair; MC1R/MITF/tyrosinase signaling; Polygonum multiflorum; melanin synthesis; zebrafish.