P. Palozza et al., PROOXIDANT ACTIVITY OF BETA-CAROTENE UNDER 100-PERCENT OXYGEN-PRESSURE IN RAT-LIVER MICROSOMES, Free radical biology & medicine, 19(6), 1995, pp. 887-892
The effects of the partial pressure of oxygen (pO(2)) on antioxidant e
fficiency of beta-carotene in inhibiting 2,2'-azobis(2-amidinopropane)
(AAPH)-induced lipid peroxidation are investigated in rat liver micro
somal membranes. The rate of peroxyl radicals generated by thermolysis
of AAPH at 37 degrees C is markedly higher at 150 than 760 mm Hg pO,.
At 150 mm Hg pO(2) beta-carotene acts as an antioxidant, inhibiting 2
,2'-azobis(2-amidinopropane) (AAPH)-induced Malondialdehyde (MDA) form
ation. At 760 mm Hg pO(2), it loses its antioxidant activity and shows
a prooxidant effect, increasing lipid peroxidation products. alpha-To
copherol prevents the prooxidant effect of beta-carotene in a dose-dep
endent manner. Our data provide the first evidence of a prooxidant eff
ect of beta-carotene under 100% oxygen pressure in a biological membra
ne model and point out the existence of cooperative interactions betwe
en beta-carotene and alpha-tocopherol.