Interaction of plasmenylcholine with free radicals in selected model systems
Interaction of plasmenylcholine with free radicals in selected model systems
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DOI：
10.1016/j.freeradbiomed.2017.02.029
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发表时间：
2017-05-01
影响因子：
7.4
通讯作者：
Sarna, T.
中科院分区：
文献类型：
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作者：
Broniec, A.;Zadlo, A.;Sarna, T.
缩醛磷脂（猪）-天然存在的甘油磷脂，在sn-1位具有乙烯基醚基团，通常被视为生理抗氧化剂。尽管在细胞培养物和实验动物中有许多缩醛磷脂抗氧化作用的例子，但由于这些研究的实质性限制，这一假设远未得到令人满意的证明。因此，细胞中的缩醛磷脂反应性导致有毒副产物的积累，并且实验设计通常过于复杂，无法评估仅一种类型的脂质分子种类的保护功能。在这项研究中，实验进行了均匀和非均匀的模型系统组成的解决方案，在有机溶剂以及胶束和脂质体含有纯合成的plasmenylcholines。在所用的实验条件下，缩醛磷脂的化学反应性可归因于特定的脂肪酸酯化模式。这是重要的，因为化学反应性不能与脂质的物理化学性质分开。通过碘量法和HPLC-EC测定磷脂和胆固醇氢过氧化物的时间依赖性形成。采用EPR血氧仪和Clark电极检测氧浓度的变化。通过标准比色TBARS方法以及MALDI-TOF质谱法监测所研究的脂质的氧化。我们的数据表明，在过氧自由基诱导或铁催化的过氧化反应中，sn-2单不饱和乙烯基醚脂质的反应性与它们的二酰基类似物相当。在含有胆固醇和缩醛磷脂的样品中，氧化过程导致胆固醇的自由基氧化产物的积累。可以得出结论，缩醛磷脂的抗氧化作用发生在分子内，而不是分子间，并取决于酯化脂肪酸的不饱和度。因此，尽管缩醛磷脂在特殊条件下可能表现出保护作用，但它是否真的可以被视为“内源性抗氧化剂”仍值得怀疑。
Plasmalogens (Pig) - naturally occurring glycerophospholipids with the vinyl-ether group in the sn-1 position are generally viewed as physiological antioxidants. Although there are numerous examples of antioxidant action of plasmalogen in cell cultures and in experimental animals, this hypothesis is far from being satisfactorily proven due to substantial limitations of such studies. Thus, plasmalogen reactivity in cells results in the accumulation of toxic byproducts and the experimental design is usually too complicated to evaluate the protective function of solely one type of lipid molecular species. In this study, experiments were performed in homogenous and heterogeneous model systems consisting of solutions in organic solvents as well as micelles and liposomes containing pure synthetic plasmenylcholines. Under the experimental conditions used, chemical reactivity of plasmalogens could be attributed to specific fatty acid esterification pattern. This is important because the chemical reactivity cannot be separated from physico-chemical properties of the lipids. Time-dependent formation of phospholipid and cholesterol hydroperoxides were determined by iodometric assay and HPLC-EC. EPR oximetry and Clark electrode were employed to detect the accompanying changes in oxygen concentration. Oxidation of the studied lipids was monitored by standard colorimetric TBARS method as well as MALDI-TOF mass spectrometry. Our data indicate that the reactivity of sn-2 monounsaturated vinyl ether lipids in peroxyl radical-induced or iron-catalyzed peroxidation reactions is comparable with that of their diacyl analogs. In samples containing cholesterol and plasmalogens, oxidative processes lead to accumulation of the radical oxidation product of cholesterol. It can be concluded that the antioxidant action of plasmalogens takes place intramolecularly rather than intermolecularly and depends on the degree of unsaturation of esterified fatty acids. Thus, it is questionable if plasmalogens can really be viewed as "endogenous antioxidant", even though they may exhibit, under special conditions, protective effect.