Human Low-Density Lipoprotein Oxidation: Hypochlorous Acid Leads to the Generation of Lysophosphatidylcholines Under Acidic Conditions

The oxidative modification of the lipid moiety of low-density lipoproteins (LDL) by reactive oxygen species (ROS) is assumed to play an important role in the pathogenesis of atherosclerosis. In this study MALDI-TOF MS and 31P NMR spectroscopy were used in order to investigate the effects of HOCl and hydroxyl radicals on LDL. Incubations of LDL with HOCl were performed at different pH values and acidic conditions favored the yield of oxidation products. An increased content of lysophosphatidylcholine (LPC) as a stable reaction product was only detected when HOCl was used, whereas HO radicals led to the disappearance of all peaks in the mass spectrum. Therefore, it is concluded that the content of LPC in LDL preparations can be used as an important diagnostic criterion of HOCl-induced LDL modifications. Accordingly, phospholipases are no prerequisite of LPC generation.