Antioxidant actions of beta-carotene in liposomal and microsomal membranes: Role of carotenoid-membrane incorporation and alpha-tocopherol
Antioxidant actions of beta-carotene in liposomal and microsomal membranes: Role of carotenoid-membrane incorporation and alpha-tocopherol
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DOI：
10.1006/abbi.1996.9822
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发表时间：
1997-02-15
影响因子：
3.9
通讯作者：
Kaysen, KL
中科院分区：
文献类型：
--
作者：
Liebler, DC;Stratton, SP;Kaysen, KL
β-胡萝卜素和其它类胡萝卜素被广泛认为是生物抗氧化剂。然而，最近的临床试验表明，β-胡萝卜素补充剂在预防疾病方面无效，并对类胡萝卜素抗氧化作用的生物学意义提出了质疑。为了进一步探讨这个问题，我们重新评估了β-胡萝卜素在脂质体和生物膜系统中的抗氧化作用。在二亚油酰磷脂酰胆碱脂质体中，其中0.35摩尔%的β-胡萝卜素被纳入到脂质体制备过程中的双层，类胡萝卜素抑制脂质过氧化反应引发的10 mM偶氮双[脒基丙烷盐酸盐]（AAPH）。在加入相同量的β-胡萝卜素的不含类胡萝卜素的脂质体悬浮液中，没有观察到抗氧化作用。在体外向大鼠肝微粒体补充β-胡萝卜素，产生的微粒体含有1.7 nmol β-胡萝卜素mg（-1）和0.16 nmol α-生育酚mg（-1）微粒体蛋白。在空气气氛下，用10 mM AAPH孵育的β-胡萝卜素补充微粒体中，直到α-生育酚耗尽约60%才发生脂质过氧化反应。β-胡萝卜素没有表现出明显的抗氧化作用，并且在孵育中没有显著消耗。当在3.8 ℃ O-2下进行孵育时，获得了类似的结果。在蒙古沙鼠的肝微粒体中，β-胡萝卜素水平为α-生育酚水平的16-37%。尽管β-胡萝卜素和α-生育酚消耗的动力学相似，但在β-胡萝卜素补充的微粒体中AAPH诱导的脂质过氧化的动力学与未补充动物的微粒体中没有差异。结果表明，β-胡萝卜素是无效的抗氧化剂时，添加到预制的脂质双层膜和α-生育酚是一个更有效的膜抗氧化剂比β-胡萝卜素，无论类胡萝卜素膜掺入的方法。这些结果支持重新评估β-胡萝卜素在生物膜中的抗氧化作用。(C)北京：科学出版社.
beta-Carotene and other carotenoids are widely regarded as biological antioxidants. However, recent clinical trials indicate that beta-carotene supplements are not effective in disease prevention and raise questions about the biological significance of carotenoid antioxidant actions. To further explore this issue, we have reevaluated the antioxidant actions of beta-carotene in liposomal and biological membrane systems. In dilinoleoylphosphatidylcholine liposomes in which 0.35 mol % beta-carotene was incorporated into the bilayer during liposome preparation, the carotenoid inhibited lipid peroxidation initiated by 10 mM azobis[amidino-propane HCl] (AAPH). In carotenoid-free liposome suspensions to which the same amount of beta-carotene was added, no antioxidant effect was observed. Supplementation of rat liver microsomes with beta-carotene in vitro yielded microsomes containing 1.7 nmol p-carotene mg(-1) and 0.16 nmol alpha-tocopherol mg(-1) microsomal protein. In beta-carotene supplemented microsomes incubated with 10 mM AAPH under an air atmosphere, lipid peroxidation did not occur until alpha-tocopherol was depleted by approximately 60%. beta-Carotene exerted no apparent antioxidant effect and was not significantly depleted in the incubations. Similar results were obtained when the incubation was done at 3.8 torr O-2. In liver microsomes from Mongolian gerbils fed beta-carotene-supplemented diets, beta-carotene levels were 16-37% of alpha-tocopherol levels. The kinetics of AAPH-induced lipid peroxidation were no different in beta-carotene-supplemented microsomes than in microsomes from unsupplemented animals, although the kinetics of beta-carotene and alpha-tocopherol depletion were similar. The results indicate that beta-carotene is ineffective as an antioxidant when added to preformed lipid bilayer membranes and that alpha-tocopherol is a much more effective membrane antioxidant than beta-carotene, regardless of the method of carotenoid-membrane incorporation. These results support a reevaluation of the proposed antioxidant role for beta-carotene in biological membranes. (C) 1997 Academic Press.