权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Free-Radical Scavenging Reactions of Vitamin E on Biological Membrane Systems

维生素 E 对生物膜系统的自由基清除反应

基本信息

批准号：
08660151
负责人：
YAMAUCHI Ryo
金额：
$ 1.47万
依托单位：
Gifu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08660151/
关键词：
Vitamin E Lipid peroxidation Liposome alpha-Tocopherol Phosphatidylcholine Hydroperoxide リポソーム

项目摘要

The addition products of alpha-tocopherol (alpha-TH) with peroxyl radicals of phosphatidylcholines (PCs) ; 1-palmitoyl-2-linoleoyl-PC,1-palmitoyl-2-linolenoy-PC,1-palmitoyl-2-arachidonoyl-PC,and 1-stearoyl-2-arachidonoyl-PC,were isolated and identified as 8a-(PC-dioxy)-alpha-tocopherones. Large-unilamellar liposomal suspensions of PC containing alpha-TH (0.1 mol%, based on PC) were oxidized at 37ﾟC.The oxidation was initiated by a water-soluble free radical initiator or by Fe (III) -EDTA and ascorbate. In all the oxidation systems, alpha-TH suppressed the formation of PC hydroperoxides until all the alpha-TH had been depleted. The oxidation products of alpha-TH were 8a- (PC-dioxy) -alpha-tocopherones, 5,6-epoxy-alpha-tocopherylquinone, 2,3-epoxy-alpha-tocopherylquinone, and alpha-tocopherylquinone. The 8a- (PC-dioxy) -alpha-tocopherones were decomposed in the liposomes primarily by being hydrolyzed to produce alpha-tocopherylquinone. The results indicate that alpha-tocopherol can trap peroxyl radicals to form 8a- (PC-dioxy) -alpha-tocopherones which are hydrolyzed to alpha-tocopherylquinone in PC bilayrs. In another oxidation pathway, alpha-TH is oxidized by peroxyl radicals to form isomeric epoxy-alpha-tocopherylquinones. alpha-Tocopherol also reacted with peroxyl radicals produced from the iron-catalyzed decomposition of PC hydroperoxides to form 8a-alkyldioxy-alpha-tocopherones. The results indicate that alpha-tocopherol can react with lipid-peroxyl radicals to stop lipid peroxidation in liposomes.The lipid peroxidation was performed in the system of rat liver homogenate using a water-soluble free radical initiator. Endogenous alpha-TH in the homogenate could suppress the lipid peroxidation, and alpha-tocopherylquinone was detected as the oxidation products. However, the free-radical scavenging mechanism of alpha-TH in biological systmes is still unclear.

α-生育酚（α-TH）与磷脂酰胆碱（PC）过氧自由基的加成产物：1-棕榈酰-2-亚油酰-PC、1-棕榈酰-2-亚麻酰-PC、1-棕榈酰-2-花生四烯酸酰-PC和1-硬脂酰-2-花生四烯酸酰-PC被分离和鉴定为8 α-（PC-二氧）-α-生育酮。含有α-TH（0.1摩尔%，基于PC）的PC的大单层脂质体悬浮液在37 ℃下氧化。氧化由水溶性自由基引发剂或Fe（III）-EDTA和抗坏血酸盐引发。在所有的氧化系统中，α-TH抑制PC氢过氧化物的形成，直到所有的α-TH已经耗尽。α-TH的氧化产物为8 α-（PC-二氧基）-α-生育酮、5，6-环氧-α-生育醌、2，3-环氧-α-生育醌和α-生育醌。8 α-（PC-二氧基）-α-生育酮在脂质体中主要通过水解分解以产生α-生育醌。结果表明，α-生育酚能捕获过氧自由基，生成8 α-（PC-二氧基）-α-生育酮，8 α-（PC-二氧基）-α-生育酮在PC双层中水解生成α-生育醌。在另一种氧化途径中，α-TH被过氧化氢自由基氧化形成异构的环氧-α-生育酚醌。α-生育酚还与由PC氢过氧化物的铁催化分解产生的过氧自由基反应，形成8 α-烷基二氧基-α-生育酮。结果表明，α-生育酚能与脂质体中的脂质过氧化自由基发生反应，从而阻止脂质体中的脂质过氧化反应。匀浆中内源性α-TH可抑制脂质过氧化，氧化产物为α-生育酚醌。然而，α-TH在生物系统中清除自由基的机制尚不清楚。