title: Photoirradiation of retinyl palmitate in ethanol with ultraviolet light--formation of photodecomposition products, reactive oxygen species, and lipid peroxides.
abstract: We have previously reported that photoirradiation of retinyl palmitate (RP), a storage and ester form of vitamin A (retinol), with UVA light resulted in the formation of photodecomposition products, generation of reactive oxygen species, and induction of lipid peroxidation. In this paper, we report our results following the photoirradiation of RP in ethanol by an UV lamp with approximately equal UVA and UVB light. The photodecomposition products were separated by reversed-phase HPLC and characterized spectroscopically by comparison with authentic standards. The identified products include: 4-keto-RP, 11-ethoxy-12-hydroxy-RP, 13-ethoxy-14-hydroxy-RP, anhydroretinol (AR), and trans- and cis-15-ethoxy-AR. Photoirradiation of RP in the presence of a lipid, methyl linoleate, resulted in induction of lipid peroxidation. Lipid peroxidation was inhibited when sodium azide was present during photoirradiation which suggests free radicals were formed. Our results demonstrate that, similar to irradiation with UVA light, RP can act as a photosensitizer leading to free radical formation and induction of lipid peroxidation following irradiation with UVB light.
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA.
authors.forename: Qingsu
authors.initials: Q
authors.lastname: Xia
authors.forename: Jun J
authors.initials: JJ
authors.lastname: Yin
authors.forename: Wayne G
authors.initials: WG
authors.lastname: Wamer
authors.forename: Shu-Hui
authors.initials: SH
authors.lastname: Cherng
authors.forename: Mary D
authors.initials: MD
authors.lastname: Boudreau
authors.forename: Paul C
authors.initials: PC
authors.lastname: Howard
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
authors.forename: Peter P
authors.initials: PP
authors.lastname: Fu
mesh_terms: D017666:Deuterium Oxide / Q000737:chemistry; D004224:Diterpenes; D000431:Ethanol / Q000737:chemistry / Q000528:radiation effects; D008041:Linoleic Acids / Q000737:chemistry* / Q000528:radiation effects; D015227:Lipid Peroxidation; D017382:Reactive Oxygen Species / Q000737:chemistry; D000084562:Retinyl Esters; D019810:Sodium Azide / Q000737:chemistry; D014466:Ultraviolet Rays; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000737:chemistry / Q000528:radiation effects
chemical_list: D004224:Diterpenes; D008041:Linoleic Acids; D017382:Reactive Oxygen Species; D000084562:Retinyl Esters; D014801:Vitamin A; C014794:retinol palmitate; C005575:methyl linoleate; D000431:Ethanol; D019810:Sodium Azide; D017666:Deuterium Oxide