title: Pigmentation effects of solar-simulated radiation as compared with UVA and UVB radiation.
abstract: Different wavelengths of ultraviolet (UV) radiation elicit different responses in the skin. UVA induces immediate tanning and persistent pigment darkening through oxidation of pre-existing melanin or melanogenic precursors, while UVB induces delayed tanning which takes several days or longer to develop and requires activation of melanocytes. We compared the effects of a 2-week repetitive exposure of human skin to solar-simulated radiation (SSR), UVA or UVB at doses eliciting comparable levels of visible tanning and measured levels of melanins and melanin-related metabolites. Levels of eumelanin and pheomelanin were significantly higher in the order of SSR, UVB, UVA or unexposed control skin. Levels of free 5-S-cysteinyldopa (5SCD) were elevated about 4-fold in SSR- or UVB-exposed skin compared with UVA-exposed or control skin. Levels of protein-bound form of 5SCD tended to be higher in SSR- or UVB-exposed skin than in UVA-exposed or control skin. Total levels of 5-hydroxy-6-methoxyindole-2-carboxylic acid (5H6MI2C) and 6H5MI2C were higher in SSR- than in UVB-exposed or control skin. These results show that SSR is more effective in promoting delayed tanning than UVB radiation alone, suggesting a synergistic effect of UVA radiation. Furthermore, free 5SCD may serve as a good marker of the effect of SSR and UVB.
authors.affiliation: Beiersdorf AG, R&D, Skin Research Center, Hamburg, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Wolber
authors.forename: Kathrin
authors.initials: K
authors.lastname: Schlenz
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Wakamatsu
authors.forename: Christoph
authors.initials: C
authors.lastname: Smuda
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Nakanishi
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Hearing
authors.forename: Shosuke
authors.initials: S
authors.lastname: Ito
mesh_terms: D000328:Adult; D003548:Cysteinyldopa / Q000378:metabolism; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D005260:Female; D006801:Humans; D007211:Indoles / Q000378:metabolism; D008297:Male; D008543:Melanins / Q000378:metabolism; D008875:Middle Aged; D011829:Radiation Dosage; D012867:Skin / Q000378:metabolism / Q000528:radiation effects; D012880:Skin Pigmentation / Q000528:radiation effects*; D013472:Sunlight / Q000009:adverse effects; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D007211:Indoles; D008543:Melanins; C018362:pheomelanin; C041877:eumelanin; D003548:Cysteinyldopa; C017407:5-hydroxy-6-methoxy-2-indolylcarboxylic acid; C017408:6-hydroxy-5-methoxy-2-indolylcarboxylic acid; D004295:Dihydroxyphenylalanine