Catechins such as EGCG (found in green tea) act as proton pump inhibitors. - GreenMedInfo Summary
Gastric H+, K(+)-ATPase inhibition by catechins.
J Pharm Pharmacol. 1992 Nov;44(11):926-8. PMID: 1361539
Research Center, Taisho Pharmaceutical Co. Ltd, Ohmiya, Japan.
Five catechins, (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin and (-)-epigallocatechin gallate, inhibited gastric H+, K(+)-ATPase activity with IC50 values ranging from 1.7 x 10(-4) to 6.9 x 10(-8) M, with (-)-epigallocatechin gallate as the most potent inhibitor. The intensity of inhibitor activity paralleled the number of phenolic hydroxy groups in the molecule. The inhibition of the enzyme by (-)-epicatechin was competitive with respect to ATP and noncompetitive with respect to K+. These findings suggest that the anti-secretory and anti-ulcerogenic effects of catechins previously reported, are due to their inhibitory activity on gastric H+, K(+)-ATPase.