Eradication of Helicobacter pylori isreported to be important to prevent relapse and accelerate the healing of duodenal and gastric ulcers,1 and there are a number of treatment regimens currently used to eradicate this organism. Plaunotol isoften usedasa cytoprotective anti-ulcer medicationforgastritisand gastric ulcersin Japan. It hasalso been used in combination therapiesagainst H. pylori-associated diseases because of its strong bactericidal effect against H. pylori.Furthermore,the combination of plaunotol, clarithromycin and a proton-pump inhibitor (PPI) isreportedto eradicateH. pylori better than the combination of clarithromycin and PPI alone.2 In a previous study, we demonstrated that plaunotol enhances the anti- bacterial activitiesof clarithromycin and amoxicillin in a nude mouse model.3 However, no in vitro data on the interaction of plaunotol in combination with clarithromycin or amoxicillin have been available to date. In thisstudy, we have evaluated the antibacterial activity of plaunotol when combined with clarithromycin or amoxicillin against H. pylori by chequer-
boardtitrationandtime–killassay.Theinvivoactivitiesof the plaunotol–clarithromycin and plaunotol–amoxicillin com- binations were also examined in a C57BL/6 mouse gastritis model infected with the Sydney Strain (strain SS1) of
H. pylori