title: Squalene as a target molecule in skin hyperpigmentation caused by singlet oxygen.
abstract: Based on our previous finding (Biochem. Biophys. Res. Commun., 223, 578-582, 1996) of singlet oxygen generation from coproporphyrin excreted on the skin surface from Propionibacterium acnes, we hypothesized that singlet oxygen formed in this way under UV exposure would promote peroxidation of skin surface lipids. We found that squalene was oxidized efficiently by singlet oxygen derived from coproporphyrin under UV exposure, and that the rate constant of squalene peroxidation by singlet oxygen was ten-fold higher than that of other skin surface lipids examined. The reaction was promoted more efficiently by UVA than by UVB. Furthermore, we found that topical application of squalene peroxide induced skin hyperpigmentation through increasing prostaglandin E(2) release from keratinocytes in guinea pigs. These results suggest that squalene peroxide formation by singlet oxygen plays a key role in photo-induced skin damage.
authors.affiliation: Research Laboratories, KOSE Corporation, Azusawa, Itabashi-ku, Tokyo, Japan.
authors.forename: Akemi
authors.initials: A
authors.lastname: Ryu
authors.forename: Kumi
authors.initials: K
authors.lastname: Arakane
authors.forename: Chiharu
authors.initials: C
authors.lastname: Koide
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nagano
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D015232:Dinoprostone / Q000378:metabolism / Q000528:radiation effects; D016503:Drug Delivery Systems / Q000379:methods*; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D017495:Hyperpigmentation / Q000139:chemically induced / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D026082:Singlet Oxygen / Q000378:metabolism* / Q000528:radiation effects / Q000633:toxicity*; D012867:Skin / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D013185:Squalene / Q000031:analogs & derivatives* / Q000378:metabolism / Q000528:radiation effects / Q000633:toxicity; D014466:Ultraviolet Rays
chemical_list: C002821:2,3-oxidosqualene; D026082:Singlet Oxygen; D013185:Squalene; D015232:Dinoprostone