Resolvin

Resolvins are dihydroxy or trihydroxy metabolites of the polyunsaturated omega-3 fatty acids, primarily eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) but also docosapentaenoic acid (DPA). These metabolites have been shown to be made by the cells and tissues of various animal species and humans. Resolvin (or Rv) metabolites of EPA are termed E resolvins (RvEs), those of DHA are termed D resolvins(RvDs), and those of DPA are termed resolvins D (RvDs_n-3DPA) and resolvins T (RvTs) (RvD_n-3DPA). The EPA-derived resolvins are nonclassic eicosanoids. Certain isomers of RvDs are termed aspirin-triggered resolvin Ds (AT-RvDs) because their synthesis is initiated by aspirin-acetylated COX2 to form 17(R)-hydroxy rather than the more classical 17(S)-hydroxy resolvins whose synthesis is initiated by lipoxygenases; however, an as yet unidentified cytochrome P450 enzyme(s) also forms this 17(R)-hydroxy intermediate and thereby contributes to the production of AT-RvDs. Resolvins are members of an expanding family of polyhydroxylated polyunsaturated fatty acid (PUFA) metabolites named "specialized pro-resolving mediators" (SPM). In addition to the resolvins, SPM include lipoxin, maresin, and protectin D1 (also termed neuroprotectin) metabolites of arachidonic acid (for lipoxins) or DHA (for maresins and protectins) as well as more recently defined and therefore less fully studied metabolites of the omega-3 PUFA isomer of DPA, 7Z,10Z,13Z,16Z,19Z-docosapentaenoic acid (clupanodonic acid) and the metabolites of the N-acetylated fatty acid amide of the DHA metabolite, docosahexaenoyl ethanolamide. SPM form during the later stages of inflammatory responses, have various, often complementary anti-inflammatory, and are thought to be key mediators in resolving these responses. The putative anti-inflammatory effects of dietary omega-3 fatty acids such as fish oil, it is suggested, are due to the conversion of EPA, DHA, and/or DPA to resolvins.