title: GC-MS/MS and LC-MS/MS studies on unlabelled and deuterium-labelled oleic acid (C18:1) reactions with peroxynitrite (O=N-O-O⁻) in buffer and hemolysate support the pM/nM-range of nitro-oleic acids in human plasma.
abstract: Oleic acid (cis-9,10-octadecenoic acid) is the most abundant monounsaturated fatty acid in human blood. Peroxynitrite (ONOO(-)) is a short-lived species formed from the reaction of nitric oxide (NO) and superoxide (O2(-)). Peroxynitrite is a potent oxidizing and moderate nitrating agent. We investigated reactions of unlabelled and deuterium labelled oleic acid in phosphate buffered saline (PBS) and lysed human erythrocytes with commercially available sodium peroxynitrite (Na(+)ONOO(-)). Non-derivatized reaction products were analyzed by spectrophotometry, HPLC with UV absorbance detection, and LC-MS/MS electrospray ionization in the negative-ion mode. Reaction products were also analyzed by GC-MS/MS in the electron capture negative-ion chemical ionization mode after derivatization first with pentafluorobenzyl (PFB) bromide and then with N,O-bis(trimethylsilyl)trifluoroacetamide. Identified oleic acid reaction products in PBS and hemolysate include cis-9,10-epoxystearic acid and trans-9,10-epoxystearic acid (about 0.1% with respect to oleic acid), threo- and erythro-9,10-dihydroxy-stearic acids. Vinyl nitro-oleic acids, 9-nitro-oleic acid (9-NO2OA) and 10-nitro-oleic acid (10-NO2OA), or other nitro-oleic acids were not found to be formed from the reaction of oleic acid with peroxynitrite in PBS or hemolysate. Our in vitro study suggests that peroxynitrite oxidizes but does not nitrate oleic acid in biological samples. Unlike thiols and tyrosine, oleic acid is not susceptible to peroxynitrite. GC-MS/MS analysis of PFB esters is by far more efficient than LC-MS/MS analysis of non-derivatized oleic acid and its derivates. Our in vitro results support our previous in vivo findings that nitro-oleic acid plasma concentrations of healthy and diseased subjects are in the pM/nM-range.
authors: Institute of Clinical Pharmacology, Hannover Medical School, 30623 Hannover, Germany.
authors: Arne
authors: A
authors: Trettin
authors: Institute of Clinical Pharmacology, Hannover Medical School, 30623 Hannover, Germany.
authors: Anke
authors: A
authors: Böhmer
authors: Institute of Clinical Pharmacology, Hannover Medical School, 30623 Hannover, Germany.
authors: Alexander A
authors: AA
authors: Zoerner
authors: Institute of Clinical Pharmacology, Hannover Medical School, 30623 Hannover, Germany.
authors: Frank-Mathias
authors: FM
authors: Gutzki
authors: Institute of Clinical Pharmacology, Hannover Medical School, 30623 Hannover, Germany.
authors: Jens
authors: J
authors: Jordan
authors: Institute of Clinical Pharmacology, Hannover Medical School, 30623 Hannover, Germany. Electronic address: tsikas.dimitros@mh-hannover.de.
authors: Dimitrios
authors: D
authors: Tsikas
mesh_terms: D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D003903:Deuterium / Q000737:chemistry; D004912:Erythrocytes / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006461:Hemolysis; D006801:Humans; D006900:Hydroxylation; D009574:Nitro Compounds / Q000097:blood / Q000737:chemistry*; D019301:Oleic Acid / Q000097:blood / Q000737:chemistry*; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D002021:Buffers; D009574:Nitro Compounds; D030421:Peroxynitrous Acid; D019301:Oleic Acid; D003903:Deuterium
keywords: Epoxidation; Erythrocytes; Nitration; Oleic acid; Peroxynitrite; Tandem mass spectrometry