In-vitro and in-vivo antibacterial activity of plaunotol, a cytoprotective antiulcer agent, against Helicobacter pylori.

Recently, some antiulcer agents have been reported to have antibacterial activity against Helicobacter pylori, which is highly associated with gastritis and peptic ulcers. In-vitro and in-vivo activity of plaunotol, a cytoprotective antiulcer agent, against H. pylori was investigated. Antibacterial activity of plaunotol against a standard strain (NCTC 11637) and 14 clinical isolates was compared with those of other cytoprotective antiulcer agents: benexate, sofalcone, teprenone, cetraxate, and gefarnate, by an agar dilution method. The MIC50 and MIC90 of plaunotol against 15 strains were 6.25 and 12.5 mg/L, respectively, making it the most potent of the cytoprotective antiulcer agents. The bactericidal effect of plaunotol was investigated using an in-vitro killing assay. Plaunotol at concentrations of more than 6 mg/L induced a rapid reduction of culture turbidity, with an extensive loss of viability, within 30 min. Observation by scanning electron microscopy revealed that plaunotol caused autolysis and treated cells were deformed. In-vivo activity of plaunotol against H. pylori was examined in a nude mouse gastritis model. Plaunotol significantly decreased the number of H. pylori in the stomach of nude mice. In addition, the antiulcer agent enhanced the antibacterial activity of amoxycillin or clarithromycin in the infection model.