Synthesis of 5-oxo-6,8,11,14-eicosatetraenoic acid and identification of novel omega-oxidized metabolites in the mouse macrophage.
The metabolism of arachidonic acid by the 5-lipoxygenase pathway not only leads to the formation of leukotrienes but also to the biologically active eicosanoid 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE). The synthesis of 5-oxo-ETE was investigated in the elicited peritoneal macrophage and the formation of 5-hydroxyeicosatetraenoic acid (5-HETE) as well as 5-oxo-ETE was quantitated using stable isotope dilution tandem mass spectrometry. The metabolism of 5-oxo-ETE in these same cells led to the formation of a series of novel less lipophilic metabolites oxidized near the methyl terminus that were structurally characterized using electrospray LC/MS and LC/MS/MS. Five novel metabolites of 5-oxo-ETE were identified including 5,18-diHETE, 5,19-diHETE, 5-oxo-19-HETrE, 5-oxo-18-HETrE, and 5,19-diHETrE. These metabolites corresponded to omega-1 and omega-2 oxidation of 5-oxo-ETE presumably formed by a specific cytochrome P450. There was no evidence for the formation of omega-oxidation (20-hydroxy metabolites), which are known products of metabolism of 5-oxo-ETE in other cell types. None of the metabolites were found to elevate intracellular calcium release, suggesting that this metabolic pathway may result in inactivation of 5-oxo-ETE. This is the first report of the biosynthesis of 5-oxo-ETE by tissue resident cell outside of the blood and the formation of novel omega-1 and omega-2 oxidation of this eicosanoid.
Hevko
J M
JM
Department of Pediatrics, Division of Cell Biology, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.
Bowers
R C
RC
Murphy
R C
RC
D000818:Animals; D001095:Arachidonic Acids / Q000138:chemical synthesis* / Q000378:metabolism; D001711:Biotransformation; D002118:Calcium / Q000378:metabolism; D002384:Catalysis; D002469:Cell Separation; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006859:Hydrogen / Q000737:chemistry; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet
D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; C080828:5-oxo-6,8,11,14-eicosatetraenoic acid; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D006859:Hydrogen; D002118:Calcium