Safety assessment of two antimicrobial peptides with food industry potential application: in vitro study

Two peptides, rNterC and rTM2C, including 13 and 15 aminoacids respectively, were designed from proteins which are known to bind orto be targeted to outer mitochondrial membrane. These peptides were modified to increase antimicrobial potential considering the appropriate balance among their total net charge, amphipathicity and hydrophobicity. These peptides were able to efficiently and selectively inhibit Listeria monocytogenes (NCTC 11994-HPA - London) growth, an important foodborne pathogen. Therefore rNterC and rTM2C could be proposed in food industry to increase the shelf life of very valuable foods. In this study we assessed the toxicity of rNterC and rTM2C in a model of non-tumorigenic intestinal epithelial cells (IEC-6). Antiproliferative assay, performed at 24, 48 and 72 h, showed a weak antiproliferative effect, in particular for rNterC, however indicating an IC50>40 μM for both peptides. The intestinal epithelium when injured by various stimuli (e.g. normal digestion, toxic substances, inflammation, oxidative stress) undergoes a wound healing process. rNterC and rTM2C peptides induces a weak reduction in the restitution process both in normal and inflammatory conditions (induced by Lipopolysaccharide from E.coli plus Interferon γ) in IEC-6 with an IC50>40 μM for both peptides. Our data on IEC-6 cells indicate that rNterC and rTM2C show only a weak antiproliferative activity and a weak effect on migration rate in IEC-6. Between the two peptides the more safe seems to be rTM2C that have the best antimicrobial activity against L. monocytogenes, despite the evaluation of other parameters will be necessary to further assess its safety.