title: The water-soluble fullerene derivative "Radical Sponge" exerts cytoprotective action against UVA irradiation but not visible-light-catalyzed cytotoxicity in human skin keratinocytes.
abstract: Fullerene was entrapped in polyvinylpyrrolidone of 60-80 kDa at a molar ratio range of 0.42-0.67:1, resulting in a water-soluble derivative with a mean particle diameter of about 688 nm, named "Radical Sponge" because of its ROS-scavenging ability as previously demonstrated, and examined in the present study for its photo-biological actions toward human skin keratinocytes HaCaT. The keratinocytes were repeatedly irradiated with a visible light of wavelengths of 400-2000 nm (approximately 19,800 lux) in the presence or absence of Radical Sponge of 25-75 microM and did not exhibit any photo-cytotoxicity due to coexistent Radical Sponge as compared with the sham-irradiation control. Radical Sponge exerted a more marked cytoprotection at doses of 10-40 microM against UVA irradiation of 30 J/cm(2) when it was pre-irradiationally administered and rinsed out immediately before the irradiation, than when administered only during or after the irradiation, indicating the preventive rather than therapeutic or ray-sheltering effect of Radical Sponge on UVA injuries. Cytoprotection by Radical Sponge against UVA was achieved at the advisable range doses of 10-40 microM in contrast to no effect of polyvinylpyrrolidone alone; its dose-dependency was advantageous over that of VC-IP, a tetra-alkyl-esterized provitamin C, which became less cytoprotective above 20 microM. Thus, Radical Sponge is expected as an anti-UVA-preventive agent without visible-light-catalyzed cytotoxicity toward human skin keratinocytes.
authors.affiliation: Laboratory of Cell-Death Control BioTechnology, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima 727-0023, Japan.
authors.forename: Li
authors.initials: L
authors.lastname: Xiao
authors.forename: Hiroya
authors.initials: H
authors.lastname: Takada
authors.forename: Xue hui
authors.initials: Xh
authors.lastname: Gan
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Miwa
mesh_terms: D019610:Cytoprotection / Q000187:drug effects* / Q000528:radiation effects*; D037741:Fullerenes / Q000494:pharmacology*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects*; D008027:Light; D012867:Skin / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D012995:Solubility; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D037741:Fullerenes; D014867:Water