Characterization of the intermediate products of lipid peroxidation in phosphatidylcholine liposomes by fast-atom bombardment mass spectrometry and tandem mass spectrometry techniques

The time-course of the HO.-induced peroxidation of soybean phosphatidylcholine (PC) liposomes was monitored over 24 h by UV spectroscopy (lambda 233 nm) and by fast-atom bombardment (FAB)-MS (positive-ion mode) and FAB-tandem (mass spectrometry) techniques. At the peak of maximal oxidation, a diagnostic fingerprint, based on several [M+16](+), and [M+32](+) and [M+48](+) ions was obtained, indicative of the formation of hydroxy and mono- and di-hydroperoxy derivatives of PC with a parallel decrease in the abundance of native PC ions, The decomposition of peroxidized products (loss in 233 nm absorbance) coincides with the disappearance of all higher molecular weight species, This approach, now successfully used for the rapid detection of the intermediate products of lipid peroxidation in a relatively simple membrane system, can be applied to check the prooxidant/antioxidant status of biological membranes.