Xu Jun, Tan Tianwei, Janson Jan-Christer
Department of Bioengineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
J Chromatogr A. 2006 Dec 22;1137(1):49-55. doi: 10.1016/j.chroma.2006.10.001. Epub 2006 Oct 17.
The adsorption behaviour of (-)-epigallocatechin gallate (EGCG), the major polyphenolic substance in green tea extracts, on the cross-linked agarose gel Superose 12 HR 10/30, has been studied using a variety of solvent systems and shown to be based on a mixture of hydrogen bonding and hydrophobic interaction. The hydrogen bonding was studied in acetonitrile in the presence of different co-solvents possessing varying hydrogen bond donor (HBD) and/or hydrogen bond acceptor (HBA) characteristics. The HBA-value of the co-solvent had the highest effect whereas the HBD-value played a subordinate role. Retention due to hydrophobic interaction could be demonstrated when mobile phases containing high water content were applied. The retention of EGCG, and its analogues (-)-epigallocatechin (EGC) and (-)-catechin (C) were thus shown to be dependent on the polarity of the organic modifiers added. However, the elution order of EGC and C, was inversed to that observed in reversed phase chromatography, indicating that some hydrogen bonding was still in effect. The retardation of EGCG in the presence of a wide concentration range of acetonitrile in water confirmed the interpretation that the retention mechanism is of mixed-mode character based on both hydrogen bonding and hydrophobic interaction.
绿茶提取物中的主要多酚物质（-）-表没食子儿茶素没食子酸酯（EGCG）在交联琼脂糖凝胶Superose 12 HR 10/30上的吸附行为，已使用多种溶剂系统进行了研究，结果表明其基于氢键和疏水相互作用的混合作用。在存在具有不同氢键供体（HBD）和/或氢键受体（HBA）特性的不同共溶剂的情况下，在乙腈中研究了氢键。共溶剂的HBA值影响最大，而HBD值起次要作用。当使用高含水量的流动相时，可以证明存在疏水相互作用导致的保留。因此，EGCG及其类似物（-）-表没食子儿茶素（EGC）和（-）-儿茶素（C）的保留取决于所添加有机改性剂的极性。然而，EGC和C的洗脱顺序与反相色谱中观察到的相反，这表明仍存在一些氢键作用。在水相中存在宽浓度范围的乙腈时EGCG的滞留现象证实了以下解释：保留机制基于氢键和疏水相互作用，具有混合模式特征。
