title: Prooxidant activity of beta-carotene under 100% oxygen pressure in rat liver microsomes.
abstract: The effects of the partial pressure of oxygen (pO2) on antioxidant efficiency of beta-carotene in inhibiting 2,2'-azobis(2-amindinopropane) (AAPH)-induced lipid peroxidation are investigated in rat liver microsomal membranes. The rate of peroxyl radicals generated by thermolysis of AAPH at 37 degrees C is markedly higher at 150 than 760 mm Hg pO2. At 150 mm Hg Po2 beta-carotene acts as an antioxidant, inhibiting 2,2'-azobis(2-amidinopropane) 9AAPH0-induced Malonidaldehyde (MDA) formation. At 760 mm Hg Po2, it loses its antioxidant activity and shows a prooxidant effect, increasing lipid peroxidation products. alpha-Tocopherol prevents the prooxidant effect of beta-carotene in a dose-dependent manner. Our data provide the first evidence of a prooxidant effect of beta-carotene under 100% oxygen pressure in a biological membrane model and point out the existence of cooperative interactions between beta-carotene and alpha-tocopherol.
authors.affiliation: Institute of General Pathology, Catholic University, Rome, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Palozza
authors.forename: G
authors.initials: G
authors.lastname: Calviello
authors.forename: G M
authors.initials: GM
authors.lastname: Bartoli
mesh_terms: D000578:Amidines / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002338:Carotenoids / Q000494:pharmacology*; D004347:Drug Interactions; D005609:Free Radicals; D015227:Lipid Peroxidation / Q000187:drug effects*; D008315:Malondialdehyde / Q000378:metabolism; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D010100:Oxygen / Q000008:administration & dosage*; D010313:Partial Pressure; D051381:Rats; D017208:Rats, Wistar; D014810:Vitamin E / Q000494:pharmacology; D019207:beta Carotene
chemical_list: D000578:Amidines; D000975:Antioxidants; D005609:Free Radicals; D019207:beta Carotene; D014810:Vitamin E; D002338:Carotenoids; D008315:Malondialdehyde; C046728:2,2'-azobis(2-amidinopropane); D010100:Oxygen