Nitrite reduces the effects of HOCl on unsaturated phosphatidylcholines—a MALDI-TOF MS study

The concentration of nitrite (NO2−) increases under inflammatory conditions. However, the physiological role of nitrite is so far controversial discussed: it was reported that effects of HOCl (an important inflammation mediator) on phospholipids (PL) may be enhanced but also reduced in the presence of nitrite.In this paper a simple model system was used: unsaturated phosphatidylcholine (PC) vesicles were treated with HOCl in the presence of varying NaNO2 concentrations and the yield of reaction products was determined by MALDI-TOF MS: the extent of chlorohydrin generation was significantly reduced in the presence of NaNO2 because HOCl is consumed by the oxidation of NO2− to NO3−.Similar results were obtained when HOCl was generated by the myeloperoxidase (MPO)/H2O2/Cl− system or the experiments were carried out in the presence of a simple peptide. It is concluded that the transient products of the reaction between HOCl and NO2− do not have a sufficient reactivity to modify PL.