title: Carotenoids as cellular antioxidants.
abstract: Consumption of carotenoids is associated with an enhanced immune response and protection against neoplasia and atherosclerosis. Because these effects have been achieved using carotenoids with no pro-vitamin A activity, they are assumed to be due to the antioxidant properties of carotenoids. Carotenoids protect against photosensitized oxidation by quenching singlet oxygen. In addition, beta-carotene reacts chemically with peroxyl radicals to produce epoxide and apocarotenal products. To investigate the potential significance of these reactions to biological systems, we have used soybean lipoxygenase to generate peroxyl radical enzymatically. beta-Carotene inhibits the oxidation of linoleic acid by soybean lipoxygenase as well as the formation of the hydroperoxide product. In addition, the absorption of beta-carotene is diminished (bleached) by soybean lipoxygenase. The potential significance of these antioxidant reactions of carotenoids to biological function is discussed.
authors.affiliation: Department of Biochemistry, University of Arizona, Tucson 85724.
authors.forename: L M
authors.initials: LM
authors.lastname: Canfield
authors.forename: J W
authors.initials: JW
authors.lastname: Forage
authors.forename: J G
authors.initials: JG
authors.lastname: Valenzuela
mesh_terms: D000975:Antioxidants; D002338:Carotenoids / Q000502:physiology*; D002386:Cataract / Q000517:prevention & control; D003327:Coronary Disease / Q000517:prevention & control; D005227:Fatty Acids / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007109:Immunity; D008077:Lipoproteins, LDL / Q000378:metabolism; D008084:Lipoxygenase / Q000378:metabolism; D009369:Neoplasms / Q000517:prevention & control; D010084:Oxidation-Reduction
chemical_list: D000975:Antioxidants; D005227:Fatty Acids; D008077:Lipoproteins, LDL; D002338:Carotenoids; D006861:Hydrogen Peroxide; D008084:Lipoxygenase