Ikeda I, Imasato Y, Sasaki E, Nakayama M, Nagao H, Takeo T, Yayabe F, Sugano M
Laboratory of Nutrition Chemistry, Kyushu University School of Agriculture, Fukuoka, Japan.
Biochim Biophys Acta. 1992 Jul 29;1127(2):141-6. doi: 10.1016/0005-2760(92)90269-2.
A(-)-epicatechin (EC) and (-)-epigallocatechin (EGC) mixture and a mixture of their gallates (ECG and EGCG, respectively) markedly lowered lymphatic cholesterol absorption in rats with a cannulated thoracic duct. A mixture of ECG and EGCG was more effective in reducing cholesterol absorption than the EC and EGC mixture. These catechins also tended to decrease lymphatic absorption of triacylglycerols, although not so pronounced as in cholesterol absorption. An in vitro study on micellar solubility of cholesterol showed that these catechin mixtures precipitated cholesterol solubilized in mixed bile salt micelles in a dose-dependent manner. A mixture of ECG and EGCG more effectively precipitated micellar cholesterol than a mixture of EC and EGC. When purified EC, EGC, ECG and EGCG were used, EGCG was more effective in precipitating micellar cholesterol than ECG. The effect of EC and EGC was comparable and weaker than their gallate esters. The bile acid concentration in the micelles was not affected by these catechins. A positive correlation was observed between the amount of coprecipitated EGCG and cholesterol. These results clearly show that tea catechins, in particular their gallate esters, effectively reduce cholesterol absorption from the intestine by reducing solubility of cholesterol in mixed micelles. The observation accounts for the hypocholesterolemic effect of tea catechins.
（-）-表儿茶素（EC）和（-）-表没食子儿茶素（EGC）的混合物及其没食子酸酯混合物（分别为ECG和EGCG）显著降低了胸导管插管大鼠的淋巴胆固醇吸收。ECG和EGCG的混合物在降低胆固醇吸收方面比EC和EGC的混合物更有效。这些儿茶素也倾向于降低三酰甘油的淋巴吸收，尽管不如胆固醇吸收那样明显。一项关于胆固醇胶束溶解度的体外研究表明，这些儿茶素混合物以剂量依赖性方式沉淀溶解在混合胆盐胶束中的胆固醇。ECG和EGCG的混合物比EC和EGC的混合物更有效地沉淀胶束胆固醇。当使用纯化的EC、EGC、ECG和EGCG时，EGCG在沉淀胶束胆固醇方面比ECG更有效。EC和EGC的效果相当且比它们的没食子酸酯弱。这些儿茶素不影响胶束中的胆汁酸浓度。共沉淀的EGCG量与胆固醇之间存在正相关。这些结果清楚地表明，茶儿茶素，特别是它们的没食子酸酯，通过降低胆固醇在混合胶束中的溶解度，有效地减少了肠道对胆固醇的吸收。这一观察结果解释了茶儿茶素的降胆固醇作用。
