Ionescu Diana, Margină Denisa, Ilie Mihaela, Iftime Adrian, Ganea Constanţa
Carol Davila University of Medicine and Pharmacy, Faculty of Medicine, 8 Eroii Sanitari Blvd., 050474 Bucharest, Romania.
Food Chem Toxicol. 2013 Nov;61:94-100. doi: 10.1016/j.fct.2013.03.007. Epub 2013 Mar 20.
Cell membrane fluidity, which can be altered by oxidative stress, plays an important role in the cell physiology. Flavonoids are among the most studied food substances that prevent and/or reduce oxidative stress, but their action mechanisms are far from being understood. We performed a study on the effect of quercetin and epigallocatechin-3-gallate on 2-Dimyristoyl-sn-glycero-3-phosphocholine small unilamellar vesicles (SUVs) with different amounts of cholesterol, using Laurdan as a fluorescent probe, to put into evidence the perturbations of the phospholipid membrane fluidity and local lipid order in an attempt to decipher the action mechanism of the flavonoids at the cell membrane level. Results indicate that polyphenols modulate the transition from the gel phase to the liquid crystalline phase of SUVs in all studied membranes. SUVs with cholesterol have by themselves higher phase transition temperature and the presence of polyphenols stabilizes further the membrane. Quercetin has a dose-dependent effect on the fluidity and local order of the lipid membranes, whilst epigallocatechin-3-gallate action is not dose-dependent, the differences being attributable to the hydrophobic/hydrophilic character of the substances. The findings are discussed within the frame of earlier reports on the effect of polyphenols on artificial membranes.
细胞膜流动性可因氧化应激而改变，在细胞生理学中发挥重要作用。黄酮类化合物是研究最多的预防和/或减轻氧化应激的食物物质之一，但其作用机制远未被理解。我们以劳丹为荧光探针，研究了槲皮素和表没食子儿茶素-3-没食子酸酯对含有不同量胆固醇的二肉豆蔻酰-sn-甘油-3-磷酸胆碱小单层囊泡（SUV）的影响，以揭示磷脂膜流动性和局部脂质有序性的扰动情况，试图在细胞膜层面解读黄酮类化合物的作用机制。结果表明，在所有研究的膜中，多酚类物质调节了SUV从凝胶相到液晶相的转变。含胆固醇的SUV本身具有较高的相变温度，多酚类物质的存在进一步稳定了膜。槲皮素对脂质膜的流动性和局部有序性具有剂量依赖性作用，而表没食子儿茶素-3-没食子酸酯的作用不具有剂量依赖性，这些差异归因于物质的疏水/亲水特性。本研究结果在早期关于多酚类物质对人工膜影响的报告框架内进行了讨论。
