Inhibitory activities of lansoprazole against respiration in Helicobacter pylori.

Lansoprazole and its derivative AG-1789 dose-dependently inhibited cellular respiration by an endogenous substrate and decreased the ATP level in Helicobacter pylori cells. The inhibitory action of lansoprazole and AG-1789 against respiration was specific to substrates such as pyruvate and alpha-ketoglutarate and similar to the inhibitory action of rotenone, which is an inhibitor for the mitochondrial respiratory chain. Growth inhibition by lansoprazole and AG-1789 as well as by rotenone was augmented at high oxygen concentrations under atmospheric conditions. Since the 50% inhibitory concentrations of these compounds for the respiration were close to their MICs for H. pylori growth, the growth inhibition might be due to respiratory inhibition by these compounds.