THE INHIBITION OF RADICAL-INITIATED PEROXIDATION OF MICROSOMAL LIPIDS BY BOTH ALPHA-TOCOPHEROL AND BETA-CAROTENE

被引:138
作者
PALOZZA, P
KRINSKY, NI
机构
[1] Institute of General Pathology, Catholic University
[2] Department of Biochemistry, Tufts University School of Medicine, Boston
关键词
BETA-CAROTENE; ALPHA-TOCOPHEROL; LIPID PEROXIDATION; MICROSOMAL LIPIDS;
D O I
10.1016/0891-5849(91)90158-Y
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Rat liver microsomal lipids in hexane solution were exposed to the lipid-soluble radical initiator, azobis-isobutyronitrile (AIBN), and the antioxidant activities of alpha-tocopherol and beta-carotene have been compared. Lipid peroxidation was monitored both by conjugated diene formation at 233 nm, and by malondialdehyde (MDA) formation in the thiobarbituric acid assay at 535 nm. Diene formation was continuous for at least 120 min in the presence of 85-mu-g/ml lipid and 4 mM AIBN. Both alpha-tocopherol and beta-carotene acted as chain-breaking antioxidants, suppressing lipid peroxidation and producing an induction period at concentrations as low as 0.5 and 8-mu-M, respectively. When both of these lipid-soluble antioxidants were present together, the oxidation was strongly suppressed and the induction period was the sum of the individual antioxidants. Alpha-tocopherol and beta-carotene also inhibited MDA generation. In the presence of 170-mu-g/ml lipid and 8 mM AIBN, beta-carotene exhibited an IC50 of 1.1-mu-M and inhibited completely at 15-mu-M. Using beta-carotene, an induction period was observed, although much less pronounced than with alpha-tocopherol. Furthermore, beta-carotene inhibited MDA production in a concentration-dependent manner and exhibited an IC50 of 50-mu-M. In addition, added beta-carotene delayed the radical-initiated destruction of the endogenous alpha-tocopherol and gamma-tocopherol in this system.
引用
收藏
页码:407 / 414
页数:8
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