Pentagalloylglucose, an antisecretory component of Paeoniae radix, inhibits gastric H, K-ATPase

We purified a compound with strong inhibitory effect on H⁺, K⁺-ATPase from Paeoniae radix, which has been used in Japan for the treatment of gastritis and peptic ulcers. The compound was identified as 1,2,3,4,6,-penta-o-galloyl-β- -glucose by proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, and fast atomic bombardment mass spectrometry. The IC₅₀ of the compound for H⁺, K⁺-ATPase was 166 nmol/l. Kinetic analyses indicated that the inhibition of the enzyme by pentagalloylglucose was noncompetitive with respect to K⁺. Pentagalloylglucose had relatively weak inhibitory effects for Mg⁺-ATPase (IC₅₀: >10 μmol/l) and Na⁺, K⁺-ATPase (IC₅₀: 2.7 μmol/l). Pentagalloylglucose also inhibited the accumulation of ¹⁴C]aminopyrine in parietal cells that had been isolated from guinea pig stomach and stimulated by 10 μmol/l histamine (IC₅₀: 7.8 μmol/l) and 1 mmol/l dbc-AMP (IC₅₀: 10 μmol/l). These results suggest that pentagalloylglucose is a potent inhibitor of H⁺, K⁺-ATPase and may be responsible for inhibition of acid secretion by Paeoniae radix.