title: Interaction of oxygen and oxy-radicals with carotenoids.
abstract: Dye-sensitized photo-oxidations of liposomes are inhibited by the presence of carotenoids in the membrane. Some carotenoid bleaching occurs during the reaction. It was shown that carotenoids are capable of inhibiting free-radical-induced lipid peroxidation in liposomes as well as singlet oxygen-induced lipid peroxidation. There is little direct effect of lipid peroxides on carotenoid bleaching during the photo-oxidative reactions. The carotenoid bleaching observed during the dye-photosensitized oxidations of the liposomes appears to be due to interactions between the carotenoid pigments and either radical intermediates from type I reactions or direct chemical reaction with singlet oxygen in a type II reaction. It was concluded that carotenoid pigments function as protective agents by quenching triplet sensitizers, singlet oxygen, and radical intermediates.
mesh_terms: D002338:Carotenoids / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D005290:Ferric Compounds / Q000494:pharmacology; D005609:Free Radicals; D008081:Liposomes / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010777:Photochemistry; D013481:Superoxides / Q000378:metabolism*; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D005227:Fatty Acids; D005290:Ferric Compounds; D005609:Free Radicals; D008081:Liposomes; D008563:Membrane Lipids; D013481:Superoxides; D002338:Carotenoids; D010100:Oxygen