Epoxydocosapentaenoic acid

Epoxide docosapentaenoic acids (epoxydocosapentaenoic acids, EDPs, or EpDPEs) are metabolites of the 22-carbon straight-chain omega-3 fatty acid, docosahexaenoic acid (DHA). Cell types that express certain cytochrome P450 (CYP) epoxygenases metabolize polyunsaturated fatty acid's (PUFAs) by converting one of their double bonds to an epoxide. In the best known of these metabolic pathways, cellular CYP epoxygenases metabolize the 20-carbon straight-chain omega-6 fatty acid, arachidonic acid, to epoxyeicosatrienoic acids (EETs); another CYP epoxygenase pathway metabolizes the 20-carbon omega-3 fatty acid, eicosapentaenoic acid (EPA), to epoxyeicosatetraenoic acids (EEQs). CYP epoxygenases similarly convert various other PUFAs to epoxides (see epoxygenase) These epoxide metabolites have a variety of activities. However, essentially all of them are rapidly converted to their corresponding, but in general far less active, Vicinal (chemistry) dihydroxy fatty acids by ubiquitous cellular Soluble epoxide hydrolase (sEH; also termed Epoxide hydrolase 2). Consequently, these epoxides, including EDPs, operate as short-lived signaling agents that regulate the function of their parent or nearby cells. The particular feature of EDPs (and EEQs) distinguishing them from EETs is that they derive from omega-3 fatty acids and are suggested to be responsible for some of the beneficial effects attributed to omega-3 fatty acids and omega-3-rich foods such as fish oil.

EDPs are epoxide eicosapentaenoic acid metabolites of DHA. DHA has 6 cis (see Cis–trans isomerism) Double bonds each one of which is located between carbons 4-5, 7-8, 10-11, 13-14, 16-17, or 19-20. Cytochrome P450 epoxygenases attack any one of these double bounds to form a respective docosapentaenoic acid (DPA) epoxide regioisomer (see Structural isomer, section on position isomerism (regioisomerism)). A given epoxygenase may therefore convert DHA to 4,5-EDP (i.e. 4,5-epoxy-7Z,10Z,13Z,16Z,19Z-DPA), 7,8-EDP (i.e. 7,8-epoxy-4Z,10Z,13Z,16Z,19Z-DPA), 10,11-EDP (i.e. 10,11-epoxy-4Z,7Z,13Z,16Z,19Z-DPA), 13,14-EDP (i.e. 13,14-epoxy-4Z,7Z,10Z,16Z,19Z-DPA), 16,17-EDP (i.e. 16,17-epoxy-4Z,7Z,10Z,13Z,19Z-DPA, or 19,20-EDP (i.e. 19,20-epoxy-4Z, 7Z,10Z,13Z,16Z-DPA. The epoxygenase enzymes generally form both R/S enantiomers at each former double bound position; for example, cytochrome P450 epoxidases attack DHA at the 16,17-double bond position to form two epoxide enantiomers, 16R,17S-EDP and 16S,1517-EDP. The 4,5-EDP metabolite is unstable and generally not detected among the EDP formed by cells.

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