In Vitro Control of E nterococcus faecalis by Z ataria multilfolira B oiss, O riganum vulgare L and M entha pulegium Essential Oils

This study evaluates the antioxidant properties of the essential oils (EOs) from Zataria multiflora Boiss (ZMB), Origanum vulgare L (OVL) and Mentha pulegium (MP) and their influence on the growth, membrane permeability and cell surface characteristics of Enterococcus faecalis. Disk diffusion and micro‐well dilution were tested for the antimicrobial activity of EOs. The minimum inhibitory concentrations (MICs) of ZMB, OVL and MP were 2, 8 and 42 mg/mL, respectively. The mechanism of the antimicrobial action of EOs against E. faecalis was also studied by measurement of the release of cell constituents and observations of cells by electron microscopy. The antioxidant activities, as evaluated by inhibition of free radicals using 2, 2‐diphenyl‐1‐picrylhydrazyl method, was 26.47, 3.20 and 34.67, for ZMB, OVL and MP, respectively. These three EOs have the potential to be applied in food products both to inhibit the growth of E. faecalis and to suppress the activity of carcinogenic O2–, produced by this bacterium. Practical Application The use of essential oils (EOs) from Zataria multi flora Boiss, Origanum vulgare L and Mentha pulegium as natural antimicrobial agents would be appreciated in foodstuffs. Considering extracellular superoxide produced by Enterococcus faecalis, which damages colonic epithelial cells DNA associated with colorectal cancer, these EOs can be used as bacteria inhibitors. They can be used alone or in combination with other preservative factors in food products. Moreover, EOs recognize as interesting natural compounds with great potential as alternatives to synthetic additives. These useful properties could be improved food safety and shelf life.