title: Insights into the mechanism of Piper betle leaf-induced contact leukomelanosis using C57BL/6 mice as the animal model and tyrosinase assays.
abstract: OBJECTIVE
  Steamed piper betle leaves (PBL) were once used by many Taiwanese women to treat pigment disorders on the face. Most women claimed a quick, favourable response at first, only to be overcome with facial leukomelanosis later.
  
  
  METHODS
  C57BL/6 mice were randomly assigned to different groups to study if PBL could cause the following effects: contact dermatitis, leukomelanosis, or hair bleaching. Intracellular melanin content was measured by tyrosinase assays.
  
  
  RESULTS
  Most steamed PBL-treated mice developed contact dermatitis and postinflammatory hyperpigmentation (PIH) on their shaved backs. About half developed bleached hair to varying extents. The steamed PBL did not only bleach the hairs, but also, unexpectedly, stimulated melanocyte replication, indicated by the fact that the number of functional melanocytes in the tail epidermis increased significantly after treatment (P = 0.007). Using tyrosinase assays PBL extract at the undiluted concentration showed limited inhibition of melanogenesis, probably via melanocytotoxicity.
  
  
  CONCLUSIONS
  The leukomelanosis observed in patients might be the consequence of PIH combined with a mixed reaction (hyper- and hypopigmentation), probably due to the different volatile chemicals that surface after steaming the PBL. This conflicting mixed reaction suggests that counteractive ingredients might exist in PBL. PBL, if purified, might be a promising source of a novel bleaching agent.
authors.affiliation: Department of Dermatology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan. hnliu@vghtpe.gov.tw
authors.forename: Han-Nan
authors.initials: HN
authors.lastname: Liu
authors.forename: Tsung-Yun
authors.initials: TY
authors.lastname: Liu
authors.forename: Chih-Chiang
authors.initials: CC
authors.lastname: Chen
authors.forename: Ding-Dar
authors.initials: DD
authors.lastname: Lee
authors.forename: Yun-Ting
authors.initials: YT
authors.lastname: Chang
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D017453:Dermatitis, Irritant / Q000209:etiology* / Q000473:pathology; D005260:Female; D006201:Hair Diseases / Q000139:chemically induced / Q000473:pathology; D017495:Hyperpigmentation / Q000139:chemically induced* / Q000473:pathology; D017496:Hypopigmentation / Q000139:chemically induced*; D008543:Melanins / Q000032:analysis; D008544:Melanocytes / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D031721:Piper betle / Q000633:toxicity*; D010936:Plant Extracts / Q000494:pharmacology / Q000633:toxicity*; D018515:Plant Leaves; D011897:Random Allocation
chemical_list: D008543:Melanins; D010936:Plant Extracts