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Free Radic Biol Med. 1995 Dec;19(6):887-92.

Prooxidant activity of beta-carotene under 100% oxygen pressure in rat liver microsomes.

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  • 1Institute of General Pathology, Catholic University, Rome, Italy.


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.

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