title: Eupafolin, a skin whitening flavonoid isolated from Phyla nodiflora, downregulated melanogenesis: Role of MAPK and Akt pathways.
abstract: BACKGROUND
  In hyperpigmentation disorders marked by melanin overproduction in the skin, including melisma and freckles, melanogenesis is caused by tyrosinase overexpression. Natural medicinal resources, like Phyla nodiflora, a traditional Chinese herbal medicine, have been used for a long time to management of dermatological conditions, such as skin inflammation and melanogenesis. Eupafolin, a functional flavonoid isolated from Phyla nodiflora, is an herbal tea constituent and possesses anti-inflammatory and anticancer activities. However, molecular mechanisms of eupafolin-mediated antimelanogenesis remain unknown. We thus focused on its antimelanogenesis effects in B16F10 mouse melanoma cells.
  
  
  METHODS
  B16F10 cells were treated with eupafolin (0.01, 0.1, 1, and 10μM) in a dose-escalation-dependent manner for the determination of melanin, tyrosinase activity and melanogenesis protein levels by ELISA or western blot analysis.
  
  
  RESULTS
  Eupafolin treatment significantly reduced cellular melanin content and tyrosinase activity in a dose-dependent manner (P<0.05), and no cytotoxic effects were observed. Eupafolin was associated with reduction in the levels of phospho-cAMP response element-binding protein and microphthalmia-associated transcription factor (MITF), and downregulation of tyrosinase synthesis and tyrosinase-related protein expression, leading to inhibit melanin production. In addition, eupafolin significantly induced the phosphorylation of ERK1/2 and p38 MAPK, whereas the decreased effect was observed in the phosphorylation of Akt. Moreover, inhibitors of these signals recovered or attenuated the inhibitory effects of eupafolin on melanogenesis.
  
  
  CONCLUSIONS
  Our results seem that inhibition of Akt and activation of phospho-ERK or p38 MAPK may lead to the suppression of melanogenesis in eupafolin-treated B16F10 mouse melanoma cells.
authors.affiliation: Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Horng-Huey
authors.initials: HH
authors.lastname: Ko
authors.affiliation: Center for Drug Abuse and Addiction, China Medical University Hospital, Taichung, Taiwan.; China Medical University, Taichung, Taiwan.
authors.forename: Yao-Chang
authors.initials: YC
authors.lastname: Chiang
authors.affiliation: Department of Pediatrics, Division of Neonatology and Pediatric Hematology/Oncology, Chang Gung Memorial Hospital, Yunlin, Taiwan.
authors.forename: Ming-Horng
authors.initials: MH
authors.lastname: Tsai
authors.affiliation: Department of Nutrition and Health Sciences, Chang-Gung Institute of Technology, Taoyuan, Taiwan.; Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan.
authors.forename: Chan-Jung
authors.initials: CJ
authors.lastname: Liang
authors.affiliation: Department of Respiratory Care, Chang Gung University of Science and Technology, Chia-Yi, Taiwan.
authors.forename: Lee-Fen
authors.initials: LF
authors.lastname: Hsu
authors.affiliation: Department of Pharmacy, College of Pharmacy & Health Care, Tajen University, Taiwan.
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Li
authors.affiliation: Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Moo-Chin
authors.initials: MC
authors.lastname: Wang
authors.affiliation: Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: flyen@kmu.edu.tw.
authors.forename: Feng-Lin
authors.initials: FL
authors.lastname: Yen
authors.affiliation: Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan; Department of Nursing, Division of Basic Medical Sciences, Chang Gung University of Science and Technology, Chia-Yi, Taiwan; Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Chia-Yi, Taiwan. Electronic address: cwlee@gw.cgust.edu.tw.
authors.forename: Chiang-Wen
authors.initials: CW
authors.lastname: Lee
mesh_terms: D000818:Animals; D002460:Cell Line; D015536:Down-Regulation; D047309:Flavones / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism; D008543:Melanins / Q000096:biosynthesis*; D008545:Melanoma / Q000378:metabolism; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D010859:Pigmentation Disorders / Q000188:drug therapy; D035261:Plant Components, Aerial / Q000737:chemistry; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D029648:Verbenaceae / Q000737:chemistry*
chemical_list: D047309:Flavones; D008543:Melanins; D051057:Proto-Oncogene Proteins c-akt; D020929:Mitogen-Activated Protein Kinase Kinases; C503624:eupafolin
keywords: Eupafolin; Melanogenesis; Microphthalmia-associated transcription factor; Tyrosinase