Chiral lipidomics of monoepoxy and monohydroxy metabolites derived from long-chain polyunsaturated fatty acids

Abstract

A chiral lipidomics approach was established for comprehensive profiling of regio- and stereoisomeric monoepoxy and monohydroxy metabolites of long-chain PUFAs as generated enzymatically by cytochromes P450 (CYPs), lipoxygenases (LOXs), and cyclooxygenases (COXs) and, in part, also unspecific oxidations. The method relies on reversed-phase chiral-LC coupled with ESI/MS/MS. Applications revealed partially opposing enantioselectivities of soluble and microsomal epoxide hydrolases (mEHs). Ablation of the soluble epoxide hydrolase (sEH) gene resulted in specific alterations in the enantiomeric composition of endogenous monoepoxy metabolites. For example, the (R,S)/(S,R)-ratio of circulating 14,15-EET changed from 2.1:1 in WT to 9.7:1 in the sEH-KO mice. Studies with liver microsomes suggested that CYP/mEH interactions play a primary role in determining the enantiomeric composition of monoepoxy metabolites during their generation and release from the ER. Analysis of human plasma showed significant enantiomeric excess with several monoepoxy metabolites. Monohydroxy metabolites were generally present as racemates; however, Ca2+-ionophore stimulation of whole blood samples resulted in enantioselective increases of LOX-derived metabolites (12S-HETE and 17S-hydroxydocosahexaenoic acid) and COX-derived metabolites (11R-HETE). Our chiral approach may provide novel opportunities for investigating the role of bioactive lipid mediators that generally exert their physiological functions in a highly regio- and stereospecific manner. A chiral lipidomics approach was established for comprehensive profiling of regio- and stereoisomeric monoepoxy and monohydroxy metabolites of long-chain PUFAs as generated enzymatically by cytochromes P450 (CYPs), lipoxygenases (LOXs), and cyclooxygenases (COXs) and, in part, also unspecific oxidations. The method relies on reversed-phase chiral-LC coupled with ESI/MS/MS. Applications revealed partially opposing enantioselectivities of soluble and microsomal epoxide hydrolases (mEHs). Ablation of the soluble epoxide hydrolase (sEH) gene resulted in specific alterations in the enantiomeric composition of endogenous monoepoxy metabolites. For example, the (R,S)/(S,R)-ratio of circulating 14,15-EET changed from 2.1:1 in WT to 9.7:1 in the sEH-KO mice. Studies with liver microsomes suggested that CYP/mEH interactions play a primary role in determining the enantiomeric composition of monoepoxy metabolites during their generation and release from the ER. Analysis of human plasma showed significant enantiomeric excess with several monoepoxy metabolites. Monohydroxy metabolites were generally present as racemates; however, Ca2+-ionophore stimulation of whole blood samples resulted in enantioselective increases of LOX-derived metabolites (12S-HETE and 17S-hydroxydocosahexaenoic acid) and COX-derived metabolites (11R-HETE). Our chiral approach may provide novel opportunities for investigating the role of bioactive lipid mediators that generally exert their physiological functions in a highly regio- and stereospecific manner. A wide array of bioactive lipid mediators is generated through oxygenation reactions from PUFAs, such as arachidonic acid (AA), EPA, and DHA. Oxygenated PUFAs have also been termed “oxylipins” and comprise metabolites formed by cyclooxygenases (COXs), lipoxygenases (LOXs), and cytochrome P450 (CYP) enzymes as well as nonenzymatic oxidation reactions (1Smilowitz J.T. Zivkovic A.M. Wan Y.J. Watkins S.M. Nording M.L. Hammock B.D. German J.B. Nutritional lipidomics: molecular metabolism, analytics, and diagnostics.Mol. Nutr. Food Res. 2013; 57: 1319-1335Crossref PubMed Scopus (44) Google Scholar, 2Gabbs M. Leng S. Devassy J.G. Monirujjaman M. Aukema H.M. Advances in our understanding of oxylipins derived from dietary PUFAs.Adv. Nutr. 2015; 6: 513-540Crossref PubMed Scopus (397) Google Scholar, 3Willenberg I. Ostermann A.I. Schebb N.H. Targeted metabolomics of the arachidonic acid cascade: current state and challenges of LC-MS analysis of oxylipins.Anal. Bioanal. Chem. 2015; 407: 2675-2683Crossref PubMed Scopus (77) Google Scholar, 4Schunck W.H. Konkel A. Fischer R. Weylandt K.H. Therapeutic potential of omega-3 fatty acid-derived epoxyeicosanoids in cardiovascular and inflammatory diseases.Pharmacol. Ther. 2018; 183: 177-204Crossref PubMed Scopus (119) Google Scholar). Current methods of targeted lipidomics allow high-throughput, comprehensive, and highly sensitive quantitation of oxylipins in biological and clinical samples (5Astarita G. Kendall A.C. Dennis E.A. Nicolaou A. Targeted lipidomic strategies for oxygenated metabolites of polyunsaturated fatty acids.Biochim. Biophys. Acta. 2015; 1851: 456-468Crossref PubMed Scopus (104) Google Scholar). Most of these analytical approaches rely on LC coupled with MS/MS. Thereby, LC is performed on achiral stationary phases under reversed-phase conditions and MS mostly uses ESI for efficient ionization of the analytes. These advanced methods can measure more than one hundred different oxylipin species in one analytical run, but are unable to distinguish between the enantiomers (5Astarita G. Kendall A.C. Dennis E.A. Nicolaou A. Targeted lipidomic strategies for oxygenated metabolites of polyunsaturated fatty acids.Biochim. Biophys. Acta. 2015; 1851: 456-468Crossref PubMed Scopus (104) Google Scholar). The lack of enantiomeric resolution is an inherent property of the achiral-LC-ESI-MS/MS approaches. This feature limits the conclusions that can be drawn regarding the enzymatic versus nonenzymatic origin of oxylipin species or the biological significance of changes in the endogenous oxylipin profile, e.g., in the course of cardiovascular and inflammatory diseases. To address these questions, different strategies of targeted chiral lipidomics are under investigation (6Mesaros C. Blair I.A. Targeted chiral analysis of bioactive arachidonic acid metabolites using liquid-chromatography-mass spectrometry.Metabolites. 2012; 2: 337-365Crossref PubMed Scopus (28) Google Scholar). Chiral-LC has been primarily developed for normal-phase conditions using apolar solvent systems that preclude ESI application for efficient ionization. A way out of this problem is provided by electron capture atmospheric pressure chemical ionization (ECAPCI)-MS. This method can be coupled with normal-phase chiral-LC and requires prior derivatization of oxylipins, e.g., into their pentafluorobenzyl esters (6Mesaros C. Blair I.A. Targeted chiral analysis of bioactive arachidonic acid metabolites using liquid-chromatography-mass spectrometry.Metabolites. 2012; 2: 337-365Crossref PubMed Scopus (28) Google Scholar). Using this sensitive approach, a recent study showed stereospecific responses to in vitro stimulation of human blood samples regarding the formation of HETEs (7Mazaleuskaya L.L. Salamatipour A. Sarantopoulou D. Weng L. FitzGerald G.A. Blair I.A. Mesaros C. Analysis of HETEs in human whole blood by chiral UHPLC-ECAPCI/HRMS.J. Lipid Res. 2018; 59: 564-575Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). of chiral stationary phases that are with This approach reversed-phase chiral-LC coupled with and quantitation of the has been for the of enantiomers as well as of lipid mediators lipidomics of and the of novel Biophys. Acta. PubMed Scopus Google Scholar, C. D. G. to the of lipid A. PubMed Scopus Google Scholar, A. L. G. of metabolites and using chiral and Acta. 2018; PubMed Scopus Google Scholar). The present study was an analytical for comprehensive profiling of regio- and enantiomeric monoepoxy and monohydroxy metabolites in biological The metabolites to be targeted and HETEs derived from and derived from EPA, and and derived from DHA. of the monoepoxy can be formed as or the in the monohydroxy metabolites can in or the and conditions for reversed-phase the of the established by the enantioselectivities of soluble epoxide hydrolases and microsomal epoxide hydrolases in and to the of the targeted oxylipin in plasma and liver samples from WT and sEH-KO as well as in human The enantiomers of and 14,15-EET Blair I.A. resolution of acid enantiomers by PubMed Scopus Google as well as of and C. M. G. Fischer R. R. Konkel A. C. cytochrome P450 enzymes are of omega-3 fatty Chem. Full Text Full Text PDF PubMed Scopus Google were as by the of the as from using chiral-LC on or samples of and were using and D. A. W.H. I. and acid by human highly formation of PubMed Scopus Google Scholar). was that the enantiomers in the as the however, were to their The and enantiomers from chiral-LC were using as oxylipins as well as the of and of and were from were for a were were as and to the of their from The was in and of and for were from and were from was from acid and were from and from chiral stationary phases were from For the method was coupled with an was a of acid from to a of by with For the was coupled with an was a of acid from to a of the chiral systems were to pressure by the from to by an of of as using a of for an of between analytical was the chiral were with For the achiral an was as stationary was under conditions a of with acid in a of for by increases to to and to by the with for were and the The was for achiral analysis was performed using an coupled with an of the ESI in the ionization The and conditions for are in and quantitation were using and as for and were on of in that of the and of was as the that a of quantitation was as the that a The was using the to one of the as and were The samples were to the and of the and were and was as of the from the as from the was as the of the of the chiral methods was as between the for a of enantiomers and the as by the achiral were from and A of these was to as from liver or human plasma in of solvent samples as were as of the by the to the with the human was from and in fatty human liver microsomes were from liver microsomal and were as C. M. M. W.H. enzymatic and and role in acid PubMed Scopus Google Scholar). The hydrolase were performed in of with fatty were a of To the were by the of human or liver from WT mice. were using human liver or liver microsomal from sEH-KO with human liver microsomes were performed in the of The reactions were by of acid and of The were in and using for liver microsomal were performed in a of of of the microsomal and the a of the microsomes with for reactions were with and by of was To liver microsomes were from sEH-KO and the reactions with human liver microsomes were performed in the of the was to Hammock B.D. and of microsomal and epoxide hydrolases in PubMed Scopus Google Scholar, C. Hammock B.D. of microsomal epoxide hydrolases by and Res. PubMed Scopus Google the were with or with human liver were performed as were into under in and using samples or of liver with of were with of of and the of and of were and the samples were for of and of were The was and, to The samples were by and by The were with of by of were with the samples and with of and were with of The were into with of and to on a under a of were in of and or to were performed in with the of the and by German WT and sEH-KO were established by and were for in our Fischer S. M. C. A. Fischer R. C. A. epoxide hydrolase is a for in a of human PubMed Scopus Google Scholar, M. M. C. D. A. in soluble epoxide Google Scholar). The were under specific conditions with a and to and with an of WT and sEH-KO a in and a of The and from was as in C. M. G. Fischer R. R. Konkel A. C. cytochrome P450 enzymes are of omega-3 fatty Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). were with was and plasma was by as well as liver and samples were in and were in using a The human blood samples in the present study from a with an and changes in the formation of and metabolites R. Konkel A. A. C. R. M. omega-3 fatty the in primarily the Lipid Res. Full Text Full Text PDF PubMed Scopus Google Scholar). The blood samples for analysis were the dietary for of the plasma samples and was by of plasma samples was in vitro of whole blood samples with the or for were analysis was performed using were with the A of was are as for the and as for the in vitro the of the analytical developed for comprehensive profiling of regio- and stereoisomeric monoepoxy and monohydroxy metabolites in biological Using of the chiral-LC was performed on different stationary coupled with The and methods and of of enantiomeric of the targeted on and as well as several on A was to reversed-phase LC on a by This method was to on the of targeted of their enantiomeric of the to samples different resolution of the enantiomeric as by is and is to to samples different to samples different resolution of the enantiomeric as by is and is to M. C. of chiral acid by 2018; Scopus Google Scholar). in a of the to samples different is and is to of the enantiomers was however, and quantitation in biological were of the enantiomers was however, and quantitation in biological were of the enantiomers was however, and quantitation in biological were to samples different is and is to M. C. of chiral acid by 2018; Scopus Google of the enantiomers was however, and quantitation in biological were in a The chiral phases and are with solvent such as or This property to chiral-LC under reversed-phase conditions and to in the for highly sensitive of the The conditions and for were for and problem was the resolution of enantiomers that to as by the enantiomers of and 14,15-EET and The problem was by the chiral with a achiral or that the monohydroxy and metabolites derived from the was established and using that monoepoxy and monohydroxy metabolites derived from EPA, and in of the as by M. C. of chiral acid by 2018; Scopus Google was with of the metabolites using or as stationary were the enantiomers of and that were on and on the of chiral and the of the enantiomers were highly under the reversed-phase conditions with than were for the quantitation of metabolites on the changes in the in to different were specific for of the enantiomers and from to to on and were using samples that a of in different was with targeted as by in from to using and with and was than for in and with in For the was between and for several monohydroxy in present in the of their the chiral methods that is to and a of the and pressure as well as pressure the to be with the solvent and for and of quantitation using a of a of an of between analytical was for and resolution of the in the established was to measure the of enantiomeric monoepoxy and monohydroxy metabolites in biological several of as during the chiral of liver and plasma on of and as and the of the between and were using a of monoepoxy and monohydroxy metabolites of the of of the between and as by the chiral and achiral methods for the of the chiral methods was the of the of of enantiomers with the of the as by the achiral Using the of the were than for for and with in were also with biological in by the chiral and achiral methods To the of the novel chiral the regio- and of an in been from Hammock B.D. and of acid by epoxide Chem. Full Text PDF PubMed Google Scholar). as present in the of liver a in of the of and this the liver was to an of were performed to potential between and regarding their To liver microsomes from sEH-KO and human liver microsomes in the of a liver and human for were by the course by the and were enzymatically and from the Using this opposing enantioselectivities the and enzymes 14,15-EET as an example, and human the the microsomal enzymes to the the between and enantioselectivities were also using and or and as of monoepoxy metabolites by human and The course of was in using or as was with of human or as in human liver of and by human The was with 14,15-EET with and with of human of and by human The was with 14,15-EET with and with of human liver in the of the are as from significant enantioselectivities were as also for regarding the enantioselective of and are by of than of with a of microsomal and enzymes has been that may the to generated A.C. A. M. for a formation between and in by analysis of in the PubMed Scopus Google Scholar, M.L. A. R. A.C. hydrolase epoxyeicosanoids and Chem. 2018; Full Text Full Text PDF PubMed Scopus Google Scholar). that interactions also the of microsomal To this the generation of by and human liver microsomes in the and of the Hammock B.D. and of microsomal and epoxide hydrolases in PubMed Scopus Google Scholar, C. Hammock B.D. of microsomal epoxide hydrolases by and Res. PubMed Scopus Google Scholar). was in to microsomal formation by more than from achiral were by using liver microsomes from sEH-KO or the with in the liver microsomes generated as well as as primary metabolites. was with significant changes in the enantiomeric composition of the liver the with the human liver the of was an of The specific were in with the of the enzymes as revealed with These that enzymes enantiomers their formation by microsomal the enantiomeric composition of a monohydroxy of that was by liver microsomal enzymes Ablation of the gene has been to the role of in cardiovascular and inflammatory Hammock B.D. epoxide gene and 2013; PubMed Scopus Google Scholar, Hammock B.D. epoxide hydrolase as a for cardiovascular PubMed Scopus Google however, the of on the enantiomeric composition of endogenous monoepoxy metabolites To address this liver and plasma samples from WT and sEH-KO mice. The were with a in and to the whole of metabolites targeted by our chiral with sEH-KO showed and plasma of the of and the were or changes of the enantiomeric were for the and that were by sEH-KO the the enantiomeric were different with several liver or plasma samples from WT and sEH-KO mice. is that the specific increases in sEH-KO for the of and as well as for were in with the of these enantiomers by the under in vitro conditions and a of potential the novel chiral methods for determining the enantiomeric composition of monoepoxy and monohydroxy metabolites in human The samples were from in a study the dietary for R. Konkel A. A. C. R. M. omega-3 fatty the in primarily the Lipid Res. Full Text Full Text PDF PubMed Scopus Google Scholar). targeted were present their and be the monoepoxy metabolites a significant enantiomeric excess was with and The chiral analysis of monohydroxy metabolites revealed that were circulating as of and under conditions a was monohydroxy by whole blood samples with the these blood samples from dietary in Ca2+-ionophore stimulation resulted in of the and in with the that these metabolites were by the highly stereospecific of is that the of was also generated in an Ca2+-ionophore stimulation a COX-derived was the formation the enantiomeric composition of was stereospecific formation of monohydroxy metabolites in human whole blood samples from dietary and with or for The enantiomeric composition of the targeted metabolites was using are as and and the of the metabolites as of the significant excess of enantiomers was as versus the present established an analytical for comprehensive profiling of regio- and stereoisomeric oxylipins in biological The targeted metabolites monoepoxy and monohydroxy metabolites as generated from EPA, and through and reactions as well in part, unspecific oxygenation The resolution and quantitation of the enantiomers on reversed-phase chiral-LC coupled with highly sensitive by our on the role of epoxide hydrolases in determining the enantiomeric composition of endogenous this approach may provide novel opportunities for investigating the and of bioactive lipid the approach also has potential for between monohydroxy metabolites formed by or enzymes and generated as nonenzymatic oxidation our the and achiral-LC-ESI-MS/MS methods performed in and using the as well as and conditions for quantitation of the metabolites. our and strategies to chiral-LC with (6Mesaros C. Blair I.A. Targeted chiral analysis of bioactive arachidonic acid metabolites using liquid-chromatography-mass spectrometry.Metabolites. 2012; 2: 337-365Crossref PubMed Scopus (28) Google Scholar, L.L. Salamatipour A. Sarantopoulou D. Weng L. FitzGerald G.A. Blair I.A. Mesaros C. Analysis of HETEs in human whole blood by chiral UHPLC-ECAPCI/HRMS.J. Lipid Res. 2018; 59: 564-575Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar, lipidomics of and the of novel Biophys. Acta. PubMed Scopus Google Scholar, C. D. G. to the of lipid A. PubMed Scopus Google Scholar, A. L. G. of metabolites and using chiral and Acta. 2018; PubMed Scopus Google are the with the advanced achiral methods that allow and the of more than one hundred different oxylipins (5Astarita G. Kendall A.C. Dennis E.A. Nicolaou A. Targeted lipidomic strategies for oxygenated metabolites of polyunsaturated fatty acids.Biochim. Biophys. Acta. 2015; 1851: 456-468Crossref PubMed Scopus (104) Google Scholar). The of oxylipin species targeted by chiral methods can be e.g., by the metabolites of of the chiral stationary phases to have the property of the of regio- and stereoisomeric oxylipins, as for to analytical on different chiral phases in to of the targeted on and as well as several on or with to chiral-LC coupled with for the targeted lipidomics of and lipid mediators lipidomics of and the of novel Biophys. Acta. PubMed Scopus Google Scholar, C. D. G. to the of lipid A. PubMed Scopus Google Scholar, A. L. G. of metabolites and using chiral and Acta. 2018; PubMed Scopus Google Scholar). and in between analytical and conditions for the analysis of biological samples in the are problem the in our chiral of chiral phases may to these e.g., by pressure using novel chiral been in the of that established formation as the of the and molecular of the cytochrome P450 arachidonic acid Lipid PubMed Scopus Google Scholar, acid cytochrome P450 Lipid Res. Full Text Full Text PDF PubMed Scopus Google Scholar). were formation S. S. L. resolution of the arachidonic acid PubMed Scopus Google Scholar, C. Blair I.A. Analysis of by chiral capture atmospheric pressure chemical ionization using PubMed Scopus Google Scholar, and of arachidonic acid by human cytochromes P450 and Ther. Google Scholar, S. and of a human cytochrome P450 arachidonic acid highly in Chem. Full Text Full Text PDF PubMed Scopus Google Hammock B.D. and of acid by epoxide Chem. Full Text PDF PubMed Google and the of into A. A novel of Chem. Full Text PDF PubMed Google Scholar). enzymes were also to the of and to and in a regio- and stereospecific D. A. W.H. I. and acid by human highly formation of PubMed Scopus Google Scholar, M. W.H. acid by cytochrome P450 enzymes of the Biophys. Res. PubMed Scopus (77) Google Scholar, D. S. M. L. of the of polyunsaturated fatty by human cytochromes Lipid Res. Full Text Full Text PDF PubMed Scopus Google Scholar). that and biological are this was responses J.T. D. of on and Google Scholar, M.L. M. acid metabolites are novel PubMed Scopus Google on M. of by a PubMed Scopus Google and C. M. G. Fischer R. R. Konkel A. C. cytochrome P450 enzymes are of omega-3 fatty Chem. Full Text Full Text PDF PubMed Scopus Google in as well as the of formation and in R. W.H. I. The biological of acid in are specific to the and the Ther. PubMed Scopus Google Scholar). Our with liver microsomes that interactions may play a primary role in determining the enantiomeric composition of monoepoxy metabolites that are generated in and from the can exert their and formation the of and as M.L. A. R. A.C. hydrolase epoxyeicosanoids and Chem. 2018; Full Text Full Text PDF PubMed Scopus Google but their enantiomeric also that and enzymes different and, in part, opposing with the of this a of regarding the that the endogenous of regio- and stereoisomeric monoepoxy metabolites. The of was by specific increases of the of and in liver and plasma of sEH-KO with WT mice. that the was more with the enantiomers than with the of the This in enantiomeric composition has been but have to the of or as in of cardiovascular and inflammatory Hammock B.D. epoxide gene and 2013; PubMed Scopus Google Scholar, Hammock B.D. epoxide hydrolase as a for cardiovascular PubMed Scopus Google Scholar, Hammock B.D. epoxide hydrolase as a for inflammatory and diseases.Pharmacol. Ther. PubMed Scopus Google Scholar, S. S. A. of soluble epoxide hydrolase PubMed Scopus Google Scholar). the of may provide a novel for understanding the role of this in human R. epoxide hydrolase and role in human 2015; PubMed Scopus Google Scholar, R. and to analysis of to cardiovascular in and PubMed Scopus Google Scholar). the endogenous of and a was for their to the in M.L. A. R. A.C. hydrolase epoxyeicosanoids and Chem. 2018; Full Text Full Text PDF PubMed Scopus Google Scholar). is to that to alterations in and have an on bioactive lipid formation the are to the interactions of epoxide and in determining the of regio- and stereoisomeric fatty acid under in has been suggested that primarily as a hydrolase for the generated by the enzymes in the the into play the have been into the M.L. A. R. A.C. hydrolase epoxyeicosanoids and Chem. 2018; Full Text Full Text PDF PubMed Scopus Google Scholar). the is to a significant to in under are formed to the of fatty for The may a role are by formation in to physiological or that and, EPA, and to the The of and also on the of the epoxide hydrolases in a M.L. A. R. A.C. hydrolase epoxyeicosanoids and Chem. 2018; Full Text Full Text PDF PubMed Scopus Google Scholar). A the of generated by enzymes can in part, the of and as to exert their biological functions and to endogenous of the and this a recent study showed that from to the are generally in the C. C. Hammock B.D. of soluble epoxide hydrolase on and and Lipid Res. Full Text Full Text PDF PubMed Scopus Google Scholar). has been suggested that the of is by than the of C. C. Hammock B.D. of soluble epoxide hydrolase on and and Lipid Res. Full Text Full Text PDF PubMed Scopus Google Scholar). a potential fatty acid that are highly in the liver and were to and to their under in vitro conditions of cytochrome P450 and by fatty PubMed Scopus Google Scholar, of by soluble epoxide PubMed Scopus Google Scholar). on the role of in and of long-chain fatty fatty and Nutr. PubMed Scopus Google Scholar, G. A. into the biological functions of liver fatty acid Lipid Res. 2015; Full Text Full Text PDF PubMed Scopus Google is to that the and of fatty acid and, their and in the liver and of the can be using chiral be of to the regio- and stereoisomeric of and fatty acid in different under and and in conditions with changes in and the and of of to be under in e.g., by using in to the potential of changes that the of of by soluble epoxide PubMed Scopus Google Scholar). with a recent study (7Mazaleuskaya L.L. Salamatipour A. Sarantopoulou D. Weng L. FitzGerald G.A. Blair I.A. Mesaros C. Analysis of HETEs in human whole blood by chiral UHPLC-ECAPCI/HRMS.J. Lipid Res. 2018; 59: 564-575Abstract Full Text Full Text PDF PubMed Scopus (28) Google our chiral analysis showed that monohydroxy metabolites are generally present as in the human enantioselective responses their Ca2+-ionophore stimulation resulted in specific increases of the of and that were by the stereospecific of and enzymes in different blood I. D. M. of Biophys. PubMed Scopus Google Scholar, The for in 2015; PubMed Scopus Google Scholar, G. C. A comprehensive of and in Biophys. Res. PubMed Scopus Google Scholar). the formation of was by enzymes of arachidonic acid the of to the formation of different oxygenated Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). was also generated in a stereospecific manner. is the of and enzymatic versus nonenzymatic origin has been lipidomics of and the of novel Biophys. Acta. PubMed Scopus Google Scholar). changes with a monohydroxy to be formed by oxidation reactions R. M.L. of oxidation of arachidonic acid are with of PubMed Scopus Google Scholar). developed a reversed-phase approach that is for the profiling of regio- and stereoisomeric oxylipins in biological The targeted metabolites enantiomers of monoepoxy and monohydroxy metabolites as primarily formed by and of the established analytical may to between changes in the endogenous formation of these lipid their stereospecific biological and the of cardiovascular and inflammatory diseases. The and for with arachidonic acid cytochrome P450 acid acid acid fatty acid acid acid of quantitation microsomal epoxide hydrolase soluble epoxide hydrolase