Antibacterial effect of kaempferol and (−)-epicatechin on Helicobacter pylori

Phenolic compounds are generated by the secondary metabolism of plants and have been associated with antibacterial properties. Among bacteria affecting human health, Helicobacter pylori has been associated with gastric cancer. There is limited information about the effect of individual or grouped phenolics on H. pylori growth. Previous studies have evaluated the effect of phenolics being part of highly complex food or beverage matrices. The aim of this work was to evaluate the in vitro antibacterial effect of kaempferol and (−)-epicatechin, both individually and combined, on H. pylori in liquid and solid cultures and in co-cultures with AGS human gastric carcinoma cells. Bacterial viability tests were performed in liquid cultures with subsequent CFU/mL counting and in solid cultures by measuring inhibition haloes. Kinetic curves of bacterial growth inhibition in the presence of those phenolics, and the protective effect of (−)-epicatechin on AGS cells against H. pylori infection were characterized. (−)-Epicatechin and kaempferol displayed antibacterial activities, being (−)-epicatechin more effective than kaempferol. After the combined application of both phenols, a synergistic effect of kaempferol plus low but not high doses of (−)-epicatechin was observed. Finally, (−)-epicatechin yielded protection to AGS cells against H. pylori infection. (−)-Epicatechin and kaempferol, both individually and combined, have antibacterial properties and protective effect on H. pylori infection.