Tsuchiya H
Department of Dental Pharmacology, Asahi University School of Dentistry, 1851 Hozumi, Hozumi-cho, Motosu-gun, 501-0296, Gifu, Japan.
Chem Biol Interact. 2001 Mar 14;134(1):41-54. doi: 10.1016/s0009-2797(00)00308-2.
Green tea catechins consisting of catechin stereoisomers and their derivatives have been suggested to show biological activities through the interactions with cellular membranes. Their effects on membrane fluidity were comparatively studied by measuring fluorescence polarization of liposomal membranes prepared with phospholipids and cholesterol. All catechin stereoisomers reduced membrane fluidity by acting on the hydrophilic and hydrophobic regions of membrane bilayers at 20-500 microM. Both epicatechins in a cis form were more effective for reducing membrane fluidity than both catechins in a trans form. (-)-Epicatechin, (+)-epicatechin, (-)-catechin and (+)-catechin reduced membrane fluidity in increasing order of intensity. Such difference between optical isomers was increased by chiral cholesterol added to membrane lipids. In reversed-phase chromatographic evaluation, (-)-epicatechin and (+)-epicatechin were more hydrophobic than (-)-catechin and (+)-catechin, although hydrophobicity was not distinguishable between optical isomers. Stereospecificity in the membrane effects of catechin stereoisomers may be induced by the different hydrophobicity of geometrical isomers and the chirality of membrane lipid components. At lower concentrations (5-100 microM), (-)-epigallocatechin gallate and (-)-epicatechin gallate reduced membrane fluidity more significantly than (-)-epicatechin, suggesting that the intensive membrane effect contributes to the potent medicinal utility of (-)-epigallocatechin gallate.
由儿茶素立体异构体及其衍生物组成的绿茶儿茶素被认为可通过与细胞膜的相互作用展现生物活性。通过测量由磷脂和胆固醇制备的脂质体膜的荧光偏振，对它们对膜流动性的影响进行了比较研究。所有儿茶素立体异构体在20 - 500微摩尔浓度下通过作用于膜双层的亲水和疏水区域来降低膜流动性。顺式的两种表儿茶素比反式的两种儿茶素在降低膜流动性方面更有效。(-)-表儿茶素、(+)-表儿茶素、(-)-儿茶素和(+)-儿茶素按强度递增顺序降低膜流动性。添加到膜脂质中的手性胆固醇增加了光学异构体之间的这种差异。在反相色谱评估中，(-)-表儿茶素和(+)-表儿茶素比(-)-儿茶素和(+)-儿茶素更疏水，尽管光学异构体之间的疏水性无法区分。儿茶素立体异构体膜效应的立体特异性可能由几何异构体的不同疏水性和膜脂质成分的手性诱导。在较低浓度（5 - 100微摩尔）下，(-)-表没食子儿茶素没食子酸酯和(-)-表儿茶素没食子酸酯比(-)-表儿茶素更显著地降低膜流动性，这表明强烈的膜效应有助于(-)-表没食子儿茶素没食子酸酯强大的药用价值。
