Salmonella , a bacterial, food-borne pathogen, can contaminate meat, milk, and vegetables. While appropriate measures are available to control Salmonella , the inhibitory phytochemicals from plants are gaining increased attention. Punicalagin, a natural antibiotic, is one of the main active tannins isolated from Punica granatum L . To obtain a broader understanding of the effect of punicalagin on the cell membranes of Salmonella typhimurium , the killing kinetics, extracellular potassium concentration, release of cell constituents, intracellular pH (pH in ), membrane potential, and morphological features were characterized to elucidate the mechanisms of action. Treatment with punicalagin induced an increase in the extracellular concentrations of potassium and a release of cell constituents. A higher pH gradient, an increase in the pH in and cell membrane depolarization were observed after punicalagin treatment. Electron microscopy observations showed that the cell membrane structures of S. typhimurium were damaged by punicalagin. It is concluded that punicalagin inhibits the proliferation of S. typhimurium and destroys the integrity of the cell membrane, leading to a loss of cell homeostasis. These findings indicate that punicalagin has the potential to be used as a food preservative in order to control S. typhimurium contamination in food and reduce the risk of salmonellosis.
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