Epigallocatechin Gallate(EGCG)Inhibits the Sulfation of 1-Naphthol in a Human Colon Carcinoma Cell Line, Caco-2

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We have previously reported that epigallocatechin gallate(EGCG)strongly inhibits the in vitro phenol sulfotransfelase(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 2h of incubation, and was observed to continue for 24h, resulting in an accumulation of sulfated 1-naphthol. Sulfation was strongly inhibited by the addition of EGCG to the culture medium. The IC_<50> of EGCG was calculated to be 20μM; this value is similar to that obtained from in vitro assays(14μM)[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.
2001-09-01