Wang Shu, Noh Sang K, Koo Sung I
Department of Human Nutrition, Kansas State University, Manhattan, KS 66506, USA.
J Nutr Biochem. 2006 Jul;17(7):492-8. doi: 10.1016/j.jnutbio.2006.03.004. Epub 2006 May 18.
This study was conducted to examine whether the inhibition of intestinal lipid absorption by green tea is associated with the inhibitory effect of its catechins on pancreatic phospholipase A(2) (PLA(2)). PLA(2) activity was assayed by using 1,2-dioleoylphosphatidylcholine (DOPC), porcine pancreatic PLA(2) and catechins at varying concentrations (0.075-1.80 micromol/L). The amount of 1-oleoyl-2-hydroxyphosphatidylcholine liberated was determined by HPLC. The percentage of inhibition of PLA(2) by catechins at 0.6 micromol increased in the order of (-)-epicatechin (23.3%), (+)-catechin (CAT; 24.8%), (-)-epigallocatechin (25.7%), (-)-epicatechin gallate (39.7%) and (-)-epigallocatechin gallate (EGCG; 64.9%). In an in vivo study, ovariectomized rats with lymph cannula were infused intraduodenally for 8 h with a triolein emulsion containing [dioleoyl-1-(14)C]-phosphatidylcholine, DOPC, alpha-tocopherol (alphaTOH) and retinol (ROH) without (CAT0) or with CAT or EGCG. The lymphatic total (14)C-radioactivity was significantly lowered by EGCG (45.5+/-4.9% dose) compared with CAT (56.2+/-5.2% dose) and CAT0 (64.7+/-2.0% dose). The (14)C-radioactivity remaining in the small intestinal lumen and cecum was higher in EGCG (24.1% dose) than in CAT (9.5% dose) and CAT0 rats (9.0% dose). Significantly less (14)C radioactivity was incorporated into lymph triacylglycerol and cholesteryl ester in EGCG rats. The absorption of alphaTOH, used as a marker of extremely hydrophobic lipids, was significantly lower in EGCG (7.8+/-1.7 micromol) than in CAT (14.4+/-2.8 micromol) and CAT0 rats (16.8+/-2.1 micromol). The absorption of ROH was unaffected, whereas oleic acid output was lower in EGCG rats. The results show that EGCG inhibits the intestinal absorption of lipids, which is in part associated with its inhibition of phosphatidylcholine hydrolysis. Data suggest that EGCG may inhibit the absorption of other highly lipophilic organic compounds.
本研究旨在探讨绿茶对肠道脂质吸收的抑制作用是否与其儿茶素对胰腺磷脂酶A2（PLA2）的抑制作用相关。通过使用1,2 - 二油酰磷脂酰胆碱（DOPC）、猪胰腺PLA2和不同浓度（0.075 - 1.80微摩尔/升）的儿茶素测定PLA2活性。通过高效液相色谱法测定释放的1 - 油酰 - 2 - 羟基磷脂酰胆碱的量。儿茶素在0.6微摩尔时对PLA2的抑制百分比按以下顺序增加：（ - ） - 表儿茶素（23.3%）、（ + ） - 儿茶素（CAT；24.8%）、（ - ） - 表没食子儿茶素（25.7%）、（ - ） - 表儿茶素没食子酸酯（39.7%）和（ - ） - 表没食子儿茶素没食子酸酯（EGCG；64.9%）。在一项体内研究中，对带有淋巴插管的去卵巢大鼠十二指肠内输注含[dioleoyl - 1 - （14）C] - 磷脂酰胆碱、DOPC、α - 生育酚（αTOH）和视黄醇（ROH）的三油酸甘油酯乳剂8小时，分为不输注儿茶素（CAT0）或输注CAT或EGCG组。与CAT（56.2±5.2%剂量）和CAT0（64.7±2.0%剂量）相比，EGCG组淋巴总（14）C - 放射性显著降低（45.5±4.9%剂量）。小肠腔和盲肠中剩余的（14）C - 放射性在EGCG组（24.1%剂量）高于CAT组（9.5%剂量）和CAT0组大鼠（9.0%剂量）。EGCG组大鼠淋巴三酰甘油和胆固醇酯中掺入的（14）C放射性明显较少。作为极疏水脂质标志物的αTOH的吸收在EGCG组（7.8±1.7微摩尔）显著低于CAT组（14.4±2.8微摩尔）和CAT0组大鼠（16.8±2.1微摩尔）。视黄醇的吸收未受影响，而EGCG组大鼠油酸输出较低。结果表明，EGCG抑制肠道脂质吸收，这部分与其对磷脂酰胆碱水解的抑制作用有关。数据表明，EGCG可能抑制其他高度亲脂性有机化合物的吸收。
