Ikeda Ikuo, Kobayashi Makoto, Hamada Tadateru, Tsuda Koichi, Goto Hitomi, Imaizumi Katsumi, Nozawa Ayumu, Sugimoto Akio, Kakuda Takami
Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Kyushu University, Fukuoka 812-8581, Japan.
J Agric Food Chem. 2003 Dec 3;51(25):7303-7. doi: 10.1021/jf034728l.
It has been known that tea catechins, (-)-epicatechin (1), (-)-epigallocatechin (2), (-)-epicatechin gallate (3), and (-)-epigallocatechin gallate (4) are epimerized to(-)-catechin (5), (-)-gallocatechin (6), (-)-catechin gallate (7), and (-)-gallocatechin gallate (8), respectively, during retort pasteurization. We previously reported that tea catechins, mainly composed of 3 and 4, effectively inhibit cholesterol absorption in rats. In this study, the effect of heat-epimerized catechins on cholesterol absorption was compared with tea catechins. Both tea catechins and heat-epimerized catechins lowered lymphatic recovery of cholesterol in rats cannulated in the thoracic duct and epimerized catechins were more effective than tea catechins. The effect of purified catechins on micellar solubility of cholesterol was examined in an in vitro study. The addition of gallate esters of catechins reduced micellar solubility of cholesterol by precipitating cholesterol from bile salt micelles. Compounds 7 and 8 were more effective to precipitate cholesterol than 3 and 4, respectively. These observations strongly suggest that heat-epimerized catechins may be more hypocholesterolemic than tea catechins.
已知在高温瞬时灭菌过程中，茶儿茶素，（-）-表儿茶素（1）、（-）-表没食子儿茶素（2）、（-）-表儿茶素没食子酸酯（3）和（-）-表没食子儿茶素没食子酸酯（4）分别差向异构化为（-）-儿茶素（5）、（-）-没食子儿茶素（6）、（-）-儿茶素没食子酸酯（7）和（-）-没食子儿茶素没食子酸酯（8）。我们之前报道过，主要由3和4组成的茶儿茶素能有效抑制大鼠体内的胆固醇吸收。在本研究中，将热差向异构化儿茶素对胆固醇吸收的影响与茶儿茶素进行了比较。茶儿茶素和热差向异构化儿茶素均降低了胸导管插管大鼠体内胆固醇的淋巴回收率，且差向异构化儿茶素比茶儿茶素更有效。在一项体外研究中检测了纯化儿茶素对胆固醇胶束溶解度的影响。儿茶素没食子酸酯的添加通过使胆固醇从胆盐胶束中沉淀出来而降低了胆固醇的胶束溶解度。化合物7和8分别比3和4更有效地沉淀胆固醇。这些观察结果有力地表明，热差向异构化儿茶素可能比茶儿茶素具有更强的降胆固醇作用。
