Alkyl caffeates as anti-Helicobacter pylori and scavenger of oxidants produced by neutrophils.

Helicobacter pylori pathogenic action involves the colonization of the gastrointestinal tract and a large production of reactive oxygen species (ROS) by the neutrophils attracted to the site of infection. The aim of this study was to evaluate caffeic acid and its alkyl esters as inhibitors of the release of ROS by Helicobacter pylori activated neutrophils and their bactericidal effect. The increased hydrophobicity caused by esterification had direct consequence in their efficiency as bactericidal agents against H. pylori and inhibitors of the production of ROS by neutrophils. The minimum inhibitory concentration (MIC) decreased from higher than 1000 μg/mL (caffeic acid) to 250 μg/mL to butyl and heptyl caffeate. The release of total ROS, superoxide anion and hypochlorous acid by activated neutrophils was also significantly decreased and the esters were more efficient than the acid precursor. In conclusion, the alkyl esters of caffeic acid have two properties that are complementary for the treatment of H. pylori infections: bactericidal activity and inhibitory effect upon generation of ROS by neutrophils. Hence, we propose that these easily synthesized and non-expensive substances should be applied to in vivo experimental models of H. pylori induced gastric infections.