The application of advanced chromatographic methodsfor determination of protein nitration markers in food model systems and blockage of this markers

Nowadays, protein oxidation in food products receives increasing interest. Several biomarkers are used to quantify and characterize protein oxidation in food. However, more specific marker can be used to evaluate the role of NaNO2 and 3-nitrotyrosine (3NT) is an interesting marker for it. The protein oxidation occured in the presence of NaNO2 is called as protein nitration. Due to hazardous effect of oxidation and nitration on protein, the utilization of antioxidants is the strategy to inhibit the formation of free redicals, oxidative and nitrative stress. However, the effect of antioxidants on protein oxidation and protein nitration is poorly understood and there is no clear regarding the particular mechanisms through which phenolic compounds protect food proteins against oxidative damage. In that study, the different food suspensions were used to explain those mechanisms and that study includes three steps. First step is attiributed to explain the formation of protein nitration marker in the different food suspensions oxidized with hydroxyl radical generation systems in the presence of sodium nitrite. In the second steps, the effect of sodium nitrite and hydroxyl-radicalgenerating system on protein oxidation in food protein suspensions has studied. The connection between oxidation and nitrosation of proteins were assessed. Upon completion of the oxidation assay, samples were analyzed for the fluorescence of tryptophan (TRP), Schiff bases and dityrosine as weel as the concentration of α-aminodipic semialdehyde (AAS) ve gamma-glutamic semialdehydes (GGS), and 3-nitrotyrosine (3NT) and the correlation between some markers and 3NT was found. In the third step, the different kind of phenolic acids and flavonoids were investigated to create accurate antioxidant strategies to avoid or retard nitration reactions and their unpleasant effects. In this respect, the selected phenolic acids are gallic, sinapic, ferulic, caffeic, p-coumaric acid, chlorogenic acids and flavonoids are catechin, naringin, rytin, quersetin and epicatechin. The three concentrations of the selected phenolic compounds (10, 100 and 200 μM) were applied for food protein suspensions to evaluate the pro-oxidant and antioxidant amount. The results showed that the concentration and the chemical structure of PhAs added to food protein suspensions influenced on the behavior of such compounds. It is thought that this study will shed light on new protein oxidation and nitration studies in the future.