title: Participation of singlet oxygen in ultraviolet-a-induced lipid peroxidation in mouse skin and its inhibition by dietary beta-carotene: an ex vivo study.
abstract: Dietary beta-carotene acts as a photoprotective agent in the skin, but the exact mechanism of protection is unknown. This ex vivo study is focused on determining the mechanism of action of beta-carotene against UV-A-induced skin damage by characterizing peroxidized phosphatidylcholine (PC) and beta-carotene oxidation products. BALB/c mice were fed with basal or a beta-carotene-supplemented diet, and homogenates from their dorsal skin were prepared after 3 weeks for UV-A irradiation. Analyses revealed that the degree of lipid peroxidation in the beta-carotene group was significantly lower than that in the controls. The isomeric composition of hydroperoxy fatty acids, constituting peroxidized PC, was determined by thin-layer chromatography-blotting followed by gas chromatography/mass spectrometry (MS)/selected ion monitoring analysis. The 9- and 10-isomers of peroxidized PC, resulting from the reaction of singlet molecular oxygen ((1)O(2)) with oleic acid, were elevated in the UV-A-exposed control group compared to the experimental group. Similar results were obtained from methylene-blue-sensitized photooxidation of mouse skin lipids in vitro. Liquid chromatography/MS analysis of the homogenates confirmed the formation of beta-carotene 5,8-endoperoxide, a specific marker for the (1)O(2) reaction. These results indicate that dietary beta-carotene accumulates in the skin and acts as a protective agent against UV-A-induced oxidative damage, by quenching the (1)O(2).
authors.affiliation: Department of Food Science, Graduate School of Nutrition and Biosciences, The University of Tokushima, Tokushima 770-8503, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Bando
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hayashi
authors.forename: Saori
authors.initials: S
authors.lastname: Wakamatsu
authors.forename: Takahiro
authors.initials: T
authors.lastname: Inakuma
authors.forename: Mariko
authors.initials: M
authors.lastname: Miyoshi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nagao
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamauchi
authors.forename: Junji
authors.initials: J
authors.lastname: Terao
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000032:analysis / Q000493:pharmacokinetics / Q000494:pharmacology*; D008041:Linoleic Acids / Q000032:analysis; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010084:Oxidation-Reduction; D026082:Singlet Oxygen / Q000032:analysis / Q000378:metabolism*; D012867:Skin / Q000737:chemistry / Q000187:drug effects* / Q000528:radiation effects*; D013438:Sulfhydryl Compounds / Q000032:analysis; D013473:Sunscreening Agents / Q000032:analysis / Q000493:pharmacokinetics / Q000494:pharmacology*; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014466:Ultraviolet Rays; D024502:alpha-Tocopherol / Q000032:analysis / Q000378:metabolism; D019207:beta Carotene / Q000032:analysis / Q000493:pharmacokinetics / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D008041:Linoleic Acids; D013438:Sulfhydryl Compounds; D013473:Sunscreening Agents; D017392:Thiobarbituric Acid Reactive Substances; D019207:beta Carotene; C008456:methyl hydroxyoctadecadienoate; D026082:Singlet Oxygen; D024502:alpha-Tocopherol