title: Down-regulation of melanin synthesis and transfer by paeonol and its mechanisms.
abstract: Down-regulation of melanin synthesis and\or melanin transfer are/is required for recovery of pigmentary disorders. It is known that direct inhibitors of tyrosinase, the key enzyme in melanin synthesis, such as hydroquinone with a phenol structure, suppress melanin synthesis. We screened some herbal monomers using human melanocytes and found that paeonol, a major phenolic component of Moutan Cortex, down-regulated melanin synthesis. The melanin synthesis and tyrosinase activity were inhibited by paeonol in a dose-dependent manner. The expression levels of tyrosinase mRNA and protein were also reduced by paeonol. We further studied the inhibitory effects of paeonol on melanin transfer in co-culture of melanocytes and keratinocytes. More than 50% of inhibition of melanin transfer was observed at concentration of 200 microM of paeonol and the increased melanin transfer induced by SLIGRL, the PAR-2 activating peptide, was also reduced by paeonol. However, paeonol did not influence the expression level of PAR-2 mRNA in co-culture cells. These results indicate that the depigmenting effect of paeonol might be due to its down-regulation of melanogenesis and melanin transfer.
authors.affiliation: Institute of Dermatology, Peking Union Medical College and Chinese Academy of Medical Sciences, Nanjing, China.
authors.forename: Shi-Hai
authors.initials: SH
authors.lastname: Xie
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Chen
authors.forename: Peng-Cheng
authors.initials: PC
authors.lastname: Ma
mesh_terms: D000098:Acetophenones / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008543:Melanins / Q000235:genetics / Q000378:metabolism*; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D000098:Acetophenones; D008543:Melanins; D012333:RNA, Messenger; C013638:paeonol; D014442:Monophenol Monooxygenase