earticle

영어

Ingestion of green tea has been shown to decrease prostaglandin ?2 levels in human colorectum, suggesting that tea constituents modulate arachidonic acid metabolism. In the present study, we investigated the effects of four purified green tea catechins, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epigallocatechin-3-gallate (EGCG), and (-)-epicatechin-3-gallate (ECG), on the catalytic activity of cytosolic phospholipase A2 (cPLA2) and release of arachidonic acid and its metabolites from intact cells. At 50 uM, EGCG and ECG inhibited cPLA2 activity by 19 and 37%, respectively, whereas EC and EGC were less effective. The inhibitory effects of these catechins on arachidonic acid metabolism in intact cells were much more pronounced. At 10 uM, EGCG and ECG inhibited the release of arachidonic acid and its metabolites by 50-70% in human colon adenocarcinoma cells (HT-29) and human esophageal squamous carcinoma cells (KYSE-190 and 450). EGCG and ECG also inhibited arachidonic acid release induced by A23187, a calcium ionophore, in both HT-29 and KYSE-450 cell lines by 30-50%. The inhibitory effects of green tea catechins on cPLA2 and arachidonic acid release may provide a possible mechanism for the prevention of human gastrointestinal inflammation and cancers.