Epigallocatechin gallate (EGCG) inhibits the sulfation of 1-naphthol in a human colon carcinoma cell line, Caco-2.
We have previously reported that epigallocatechin gallate (EGCG) strongly inhibits the in vitro phenol sulfotransferase (P-ST) activity of a human colon carcinoma cell line, Caco-2. In the present study, we examined the ability of EGCG to inhibit the sulfation of 1-naphthol in intact Caco-2 cells. Sulfation of 1-naphthol was detected in Caco-2 cells after 2 h of incubation, and was observed to continue for 24 h, resulting in an accumulation of sulfated 1-naphthol. Sulfation was strongly inhibited by the addition of EGCG to the culture medium. The IC50 of EGCG was calculated to be 20 microM; this value is similar to that obtained from in vitro assays (14 microM) [Ref. Tamura et al., Biol. Pharm. Bull., 23, 695, (2000)]. These results indicate that catechins are capable of inhibiting P-ST activity in intact cells as well as in vitro. We believe that the inhibitory activity of catechins might be the mechanism by which catechins (and green tea) exert anti-carcinogenic activity against procarcinogenic compounds that require P-ST activation in vivo.
Isozaki
T
T
Kyoritsu College of Pharmacy, Tokyo, Japan. tamura-hr@kyoritsu-ph.ac.jp
Tamura
H
H
D000970:Antineoplastic Agents / Q000494:pharmacology*; D015239:Arylsulfotransferase / Q000037:antagonists & inhibitors; D018938:Caco-2 Cells; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003864:Depression, Chemical; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D009284:Naphthols / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D009284:Naphthols; D013431:Sulfates; C029350:1-naphthol; D002392:Catechin; C045651:epigallocatechin gallate; D015239:Arylsulfotransferase