Peroxyl radical scavenging by beta-carotene in lipid bilayers. Effect of oxygen partial pressure.
Peroxyl radical scavenging by beta-carotene in lipid bilayers. Effect of oxygen partial pressure.
复制标题
脂质双层中的β-胡萝卜素清除过氧自由基。
DOI：
10.1016/s0021-9258(18)42884-0
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
D. Liebler
中科院分区：
文献类型：
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作者：
T. Kennedy;D. Liebler
研究了氧分压（pO 2）对全反式-β，β-胡萝卜素（BC）在大豆磷脂酰胆碱脂质体体系中抗氧化反应的影响。偶氮-双（2，4-二甲基戊腈）在37 ℃下热分解产生的过氧自由基引发脂质过氧化。BC抑制脂质过氧化，这是监测共轭二烯的形成，高达70%，与对照组在160和15 ℃ O2。相比之下，在760 ℃ O2下，与对照相比，最大抑制约为40%，且抑制的重现性较差。过氧自由基将BC氧化为5，6-环氧-β，β-胡萝卜素和几种未鉴定的极性产物。在160 ℃时，产品形成率和BC消耗率均显著高于15 ℃时。然而，在160和760 ℃ O2下，产品形成和BC消耗的速率相似。在不含偶氮-双（2，4-二甲基戊腈）的脂质体中，160 ℃时的BC消耗仅为760 ℃时的64%。这些结果表明，自由基捕获和自氧化反应消耗BC，后者加速高pO 2。自氧化消耗BC不清除过氧自由基，可能会削弱BC的抗氧化活性，特别是在高pO 2。其抗氧化作用在15和160 ℃ O2的相似性表明，BC可以提供抗氧化保护的任何组织在正常生理范围内的pO 2。
The effect of the partial pressure of oxygen (pO2) on the antioxidant reactions of all-trans-beta, beta-carotene (BC) was investigated in a soybean phosphatidylcholine liposome system. Peroxyl radicals generated by thermolysis of azo-bis(2,4-dimethylvaleronitrile) at 37 degrees C initiated lipid peroxidation. BC inhibited lipid peroxidation, which was monitored by conjugated diene formation, by up to 70% versus control at 160 and 15 torr O2. In contrast, at 760 torr O2 the maximum inhibition was approximately 40% versus control and inhibition was less reproducible. Peroxyl radicals oxidized BC to 5,6-epoxy-beta,beta-carotene and several unidentified polar products. The rates of both product formation and BC consumption were significantly higher at 160 torr than at 15 torr O2. However, at 160 and 760 torr O2, the rates of product formation and BC depletion were similar. In liposomes without azo-bis(2,4-dimethylvaleronitrile), BC depletion at 160 torr was only 64% that at 760 torr O2. These results suggest that both radical trapping and autoxidation reactions consume BC and that the latter are accelerated by high pO2. Autoxidation consumes BC without scavenging peroxyl radicals and may attenuate BC antioxidant activity, especially at high pO2. The similarity in its antioxidant effects at 15 and 160 torr O2 suggests that BC could provide antioxidant protection to any tissue within the normal physiologic range of pO2.