Abstract
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 μmol/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 μmol 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- 14C]-phosphatidylcholine, DOPC, α-tocopherol (αTOH) and retinol (ROH) without (CAT0) or with CAT or EGCG. The lymphatic total 14C-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 14C-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 14C radioactivity was incorporated into lymph triacylglycerol and cholesteryl ester in EGCG rats. The absorption of αTOH, used as a marker of extremely hydrophobic lipids, was significantly lower in EGCG (7.8±1.7 μmol) than in CAT (14.4±2.8 μmol) and CAT0 rats (16.8±2.1 μmol). 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.
Published Version
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