TY - JOUR
T1 - Green tea catechins inhibit pancreatic phospholipase A2 and intestinal absorption of lipids in ovariectomized rats
AU - Wang, Shu
AU - Noh, Sang K.
AU - Koo, Sung I.
N1 - Funding Information:
This study was supported in part by NIH R21AT001363-01A2.
PY - 2006/8
Y1 - 2006/8
N2 - 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 A2 (PLA2). PLA2 activity was assayed by using 1,2-dioleoylphosphatidylcholine (DOPC), porcine pancreatic PLA2 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 PLA2 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.
AB - 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 A2 (PLA2). PLA2 activity was assayed by using 1,2-dioleoylphosphatidylcholine (DOPC), porcine pancreatic PLA2 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 PLA2 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.
KW - (-)-Epigallocatechin gallate
KW - Green tea
KW - Lipids
KW - Phosphatidylcholine
KW - Phospholipase A
KW - Rats
KW - α-Tocopherol
UR - http://www.scopus.com/inward/record.url?scp=33745009018&partnerID=8YFLogxK
U2 - 10.1016/j.jnutbio.2006.03.004
DO - 10.1016/j.jnutbio.2006.03.004
M3 - Article
C2 - 16713229
AN - SCOPUS:33745009018
VL - 17
SP - 492
EP - 498
JO - Journal of Nutritional Biochemistry
JF - Journal of Nutritional Biochemistry
SN - 0955-2863
IS - 7
ER -