title: Cholesteryl nitrolinoleate, a nitrated lipid present in human blood plasma and lipoproteins.
abstract: Nitric oxide (*NO) and *NO-derived reactive species (e.g., peroxynitrite anion, nitrogen dioxide radical) react with lipids containing unsaturated fatty acids to generate nitrated species. In the present work, we synthesized, characterized, and detected a nitrated derivative of cholesteryl linoleate (Ch18:2) in human blood plasma and lipoproteins using a high-pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry method. It was synthesized by a reaction of Ch18:2 with nitronium tetrafluoroborate, yielding a species with m/z 711, which is characteristic of the cholesteryl nitrolinoleate (Ch18:2NO2) ammonium adduct. The presence of the nitro group was confirmed by using [15N]nitrite, which gave a product with m/z 712, with the same chromatographic and spectrometric characteristics of those of m/z 711. Furthermore, a C-NO2 structure was also demonstrated in Ch18:2NO2 by infrared analysis (Vmax 1549, 1374 cm-1). A stable product with m/z of 711, showing the same chromatographic characteristics and fragmentation pattern as those of synthesized standard, was found in human blood plasma and lipoproteins of normolipidemic subjects. The presence of this novel nitrogen-containing lipid product in human plasma and lipoproteins could represent a potential indicator of the oxidative/nitrative roles that *NO or its metabolites play during in vivo lipid oxidation, generating a compensatory mechanism of protection in vascular disease.
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Emersom S
authors.initials: ES
authors.lastname: Lima
authors.forename: Paolo
authors.initials: P
authors.lastname: Di Mascio
authors.forename: Dulcineia S P
authors.initials: DS
authors.lastname: Abdalla
mesh_terms: D002788:Cholesterol Esters / Q000097:blood* / Q000378:metabolism; D006801:Humans; D019787:Linoleic Acid / Q000097:blood* / Q000378:metabolism; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood*; D008074:Lipoproteins / Q000737:chemistry*; D013058:Mass Spectrometry; D015394:Molecular Structure; D009566:Nitrates / Q000097:blood / Q000378:metabolism*; D010949:Plasma / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D002788:Cholesterol Esters; D008055:Lipids; D008074:Lipoproteins; D009566:Nitrates; C487539:cholesteryl nitrolinoleate; D019787:Linoleic Acid