ANALYSIS OF STABLE OXIDIZED MOLECULAR-SPECIES OF GLYCEROPHOSPHOLIPIDSFOLLOWING TREATMENT OF RED-BLOOD-CELL GHOSTS WITH T-BUTYLHYDROPEROXIDE

A model of Lipid peroxidation was employed to investigate the formatio n of oxidized phospholipids in red blood cell membranes after treatmen t with t-butylhydroperoxide (tBuOOH). On-line normal-phase HPLC/ mass spectrometry (LC/MS) with electrospray ionization was used to separate phospholipid classes and analyze the distribution of the major poly-u nsaturated fatty acyl groups and corresponding oxidation products. Ara chidonic acid was observed primarily in plasmalogen glycerophosphoetha nolamine (GPE), whereas Linoleic acid was equally distributed in 1,2-d iacyl-GPE and glycerophosphocholine (GPC) lipids. The additions of one and two oxygen atoms to poly-unsaturated phospholipid molecular speci es were observed as the major, stable products after incubation with t BuOOH. Tandem mass spectrometry was utilized to further structurally c haracterize the oxidized fatty acyl groups which were identified as 5- , 8-, 9-, 11-, 12-, and 15-hydroxy-eicosatetraenoate (HETE) and 5-, 12 -, and 15-hydroperoxyeicosatetraenoate (HpETE) in addition to 9- and 1 3-hydroxyoctadecadienoate (HODE) and 9- and 13-hydroperoxyoctadecadien oate (HpODE). Although 18:0p/20:4-GPE was the predominate phospholipid species containing arachidonic acid, the major species containing HET E and HpETE were the 1,2-diacyl-GPE with hexadecanoate as the sn-l sub stituent. This result would be consistent with a differential pathway of oxidative degradation of arachidonoyl plasmalogen GPE suggesting a unique role for this plasmalogen molecular species glycerophospholipid . (C) 1998 Academic Press.