title: Inhibitory effect of tannic acid on gastric H+,K(+)-ATPase.
abstract: The effect of tannic acid on gastric H+,K(+)-ATPase was studied. Tannic acid dose-dependently inhibited pig gastric H+,K(+)-ATPase activity with an IC50 value of 2.9 x 10(-8) M. Tannic acid also inhibited K(+)-stimulated p-nitrophenyl phosphatase (K(+)-pNPPase) activity, which is found in gastric H+,K(+)-ATPase preparations, as well as H+,K(+)-ATPase activity, with an IC50 value of 4.1 x 10(-7) M. Kinetic studies showed that the inhibition of H+,K(+)-ATPase activity by tannic acid was competitive with respect to ATP and noncompetitive with respect to K+. These results show that tannic acid is a potent inhibitor of gastric H+,K(+)-ATPase; this may be related to its anti-secretory and anti-ulcerogenic effects.
authors.affiliation: Research Center, Taisho Pharmaceutical Co. Ltd., Saitama, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Murakami
authors.forename: M
authors.initials: M
authors.lastname: Muramatsu
authors.forename: S
authors.initials: S
authors.lastname: Otomo
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005753:Gastric Mucosa / Q000187:drug effects / Q000201:enzymology*; D017506:H(+)-K(+)-Exchanging ATPase; D047348:Hydrolyzable Tannins / Q000494:pharmacology*; D013056:Spectrophotometry, Ultraviolet; D013552:Swine
chemical_list: D047348:Hydrolyzable Tannins; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase