title: Interactions of plasmalogens and their diacyl analogs with singlet oxygen in selected model systems.
abstract: Plasmalogens are phospholipids containing a vinyl-ether linkage at the sn-1 position of the glycerophospholipid backbone. Despite being quite abundant in humans, the biological role of plasmalogens remains speculative. It has been postulated that plasmalogens are physiological antioxidants with the vinyl-ether functionality serving as a sacrificial trap for free radicals and singlet oxygen. However, no quantitative data on the efficiency of plasmalogens at scavenging these reactive species are available. In this study, rate constants of quenching of singlet oxygen, generated by photosensitized energy transfer, by several plasmalogens and, for comparison, by their diacyl analogs were determined by time-resolved detection of phosphorescence at 1270nm. Relative rates of the interactions of singlet oxygen with plasmalogens and other lipids, in solution and in liposomal membranes, were measured by electron paramagnetic resonance oximetry and product analysis using HPLC-EC detection of cholesterol hydroperoxides and iodometric assay of lipid hydroperoxides. The results show that singlet oxygen interacts with plasmalogens significantly faster than with the other lipids, with the corresponding rate constants being 1 to 2 orders of magnitude greater. The quenching of singlet oxygen by plasmalogens is mostly reactive in nature and results from its preferential interaction with the vinyl-ether bond. The data suggest that plasmalogens could protect unsaturated membrane lipids against oxidation induced by singlet oxygen, providing that the oxidation products are not excessively cytotoxic.
authors.affiliation: Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Broniec
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Klosinski
authors.forename: Anna
authors.initials: A
authors.lastname: Pawlak
authors.forename: Marta
authors.initials: M
authors.lastname: Wrona-Krol
authors.forename: David
authors.initials: D
authors.lastname: Thompson
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Sarna
mesh_terms: D000215:Acylation; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D002784:Cholesterol / Q000031:analogs & derivatives / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008163:Luminescent Measurements; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010955:Plasmalogens / Q000737:chemistry / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism*; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D000975:Antioxidants; D008081:Liposomes; D010955:Plasmalogens; D014753:Vinyl Compounds; D026082:Singlet Oxygen; C100195:vinyl ether; C002843:cholesterol hydroperoxide; D002784:Cholesterol