Mass spectrometric analysis of leukotriene A4 and other chemically reactive metabolites of arachidonic acid

• Published in: Journal of the American Society for Mass Spectrometry Vol. 13; no. 10; pp. 1227 - 1234
• Main Authors: DICKINSON, Jennifer S, MURPHY, Robert C
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Science 01.10.2002; Springer Nature B.V
• Subjects: 6-Ketoprostaglandin F1 alpha - analysis; Activation; Analytical, structural and metabolic biochemistry; Anions; Arachidonic acid; Arachidonic Acid - chemistry; Arachidonic Acid - metabolism; Biological and medical sciences; Biosynthesis; Chemical attack; Chemistry; Chromatography, High Pressure Liquid; Columns (structural); Eicosanoids - analysis; Epoprostenol - analysis; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Half-life; Hydrogen-Ion Concentration; Indicators and Reagents; Ionization; Ions; Leukotriene A4 - analysis; Mass spectrometry; Metabolites; Online Systems; Organic chemistry; Other biological molecules; Oxygen Isotopes; Plant growth substances; Prostaglandin H2; Prostaglandins; Prostaglandins H - analysis; Quadrupoles; Reactivity and mechanisms; Spectrometry; Spectrometry, Mass, Electrospray Ionization; Elution; Gradient; Collisional activation; Chemical analysis; Prostaglandin I2; Metabolite; Arachidonic acid derivatives; Prostaglandin H2; HPLC chromatography; Prostaglandin E2; Fragmentation pattern; Prostaglandin D2; Electrospray; Leukotriene; Reversed phase chromatography; Analysis method; Eicosanoid; Mass spectrometry MS/MS; Mass spectrometry; Structural analysis
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1016/S1044-0305(02)00456-7

The biosynthesis of prostaglandins and leukotrienes proceeds through the formation of chemically reactive intermediates leukotriene A4 (LTA4) and prostaglandin H2 (PGH2) which in aqueous solutions have chemical half-lives of 3 s and 3 min, respectively. Prostacyclin (PGI2) is another chemically reactive prostanoid that has a chemical half-life of 3-4 min. The recent development of reversed phase HPLC stationary phases that are stable to elevated pH (pH 10-12) without significant column damage has permitted direct analysis of these acid-sensitive eicosanoids. Using electrospray ionization, molecular anions [M - H]- of these compounds were observed at m/z 317 for LTA4 and m/z 351 for both PGH2 and PGI2. The mechanism of formation of ions derived from collisional activation of LTA4 was studied using stable isotope labeled and chemical analogs of LTA4 and found to involve formation of highly conjugated anions at m/z 261 and 163. The collisional activation of the molecular anion of PGH2 yielded a product ion spectrum identical to that observed for the isomeric prostaglandins PGE2 and PGD2. However, it was possible to baseline separate PGE2, PDG2, and PGH2 by reversed phase HPLC using basic HPLC mobile phases. The collisional activation of PGI2 led to a family of abundant ions including highly conjugated carbon-centered and oxygen-centered radical species (m/z 245 and 205) likely derived from the attack of the carboxylate anion on the cyclic enolether of PGI2 as well as the most abundant product ion (m/z 215) which formed following loss of neutral hexanal and water. The structures of these product ions were consistent with high resolution measurements measured in a quadrupole time-of-flight mass spectrometer.