Potential antioxidant peptides released after simulated gastro-intestinal digestion of Stracchino soft cheese

As life expectation increases, age-related pathologies become more frequent, and thus the search for new compounds, with natural origin, possessing antioxidant and anti-inflammatory is expanding. Numerous evidences have demonstrated that milk proteins are a source of bioactive encrypted peptides. In order to exert their activity, these peptides should survive during digestion; we carried out an in vitro mnltistep gastro-intestinal digestion of Stracchino soft cheese. Considering the importance of oxidative stress conditions in many diseases, the obtained peptides were fractionated by preparative liquid chromatography and subsequently evaluated thet antioxidant potential. The effect of each fraction (250-10 pglml) was evaluated in inflammatory and oxidative shess conditions in intestinal epithelial cells (IEC-6). The fractions added to IEC-ó cells. I h before and simultaneously to pro-inflammatory stimulus (Lipopolysaccharide from E coli l0 ltglml{tr Interferon f l0 U/ml) for 24 h, significantly inhibited the release of reactive oxygen species (ROS), evaluated by flow cytometry. Among tested fractions, during inflammatory conditions, fraction number two exerted the highest effect in inhibiting ROS release in IEC-6. Fraction number two showed the highest antioxidant potential also when cells were treated with hydrogen peroxide (l mM) as pro-oxidant agent. Nrf2 is an important regulator of cellular resistance to oxidants and, among tested fractions, fraction number two showed the stronger effect in activating Nrfl2. Antiproliferative assay, evaluated by MTT test, indicated that the tested fractions did not affect IEC-6 proliferation. Peptide sequences of fraction two were determined by LC-MS/MS, identified peptides belong to beta casein, in particular most intense peak possessed sequence EAMAPK.