Anti-Helicobacter pylori agents. 4. 2-(Substituted guanidino)-4-phenylthiazoles and some structurally rigid derivatives

In order to find a new class of anti-Helicobacter pylori (H. pylori) agents , a series of 4-[(3-acetamido)phenyl]-2-(substituted guanidino)thiazoles an d some structurally rigid analoges were synthesized and evaluated for antim icrobial activity against H. pylori. Among the compounds obtained, high ant i-H. pylori activities were observed in benzyl derivative 34 (MIC = 0.025 m u g/mL) and phenethyl derivatives 35 and 36 (MIC = 0.037 mu g/mL and 0.017 mu g/mL). Though alkyl derivatives generally showed lower activity, the 2-m ethoxyethyl derivative 28 preserved significant activity (MIC = 0.32 mu g/m L) and also exhibited more potent gastric antisecretory activity than ranit idine. Structural restriction by bridging between the thiazole and the phen yl rings with an alkyl chain did not improve the activity in this series.