Eicosatetraenoic acid

Eicosatetraenoic acid (ETA) designates any straight chain 20:4 fatty acid. Eicosatetraenoic acid belongs to the family of eicosanoids, molecules synthesized from oxidized polyunsaturated fatty acids (PUFAs) to mediate cell-cell communication. The eicosanoids, working in tandem, contribute to a lipid signaling complex widely responsible for inducing an inflammatory immune response. Common signs of inflammation are both internal and external, with effects like visible redness, pain in the surrounding area, swelling, and the sensation of heat—many of these an effect of varying eicosanoid species. These effects are associated with and have been observed in patients with cancers and various neurological/metabolic disorders. See Essential Fatty Acid for nomenclature. Two isomers, both of them essential fatty acids, are of particular interest: all-cis-5,8,11,14-eicosatetraenoic acid is an ω-6 fatty acid with the trivial name arachidonic acid. It is formed by a desaturation of dihomo-gamma-linolenic acid (DGLA, 20:3 ω-6). all-cis-8,11,14,17-eicosatetraenoic acid is an ω-3 fatty acid. It is an intermediate between stearidonic acid (18:4 ω-3) and eicosapentaenoic acid (EPA, 20:5 ω-3) Some chemistry sources define 'arachadonic acid' to designate any of the eicosatetraenoic acids. However, almost all writings in biology, medicine and nutrition limit the use of the term 'arachidonic acid' to all-cis-5,8,11,14-eicosatetraenoic acid (ω-6). ETA is found in green-lipped mussel and appears to act as dual inhibitor of arachidonic acid oxygenation by both the cyclooxygenase (COX) and lipoxygenase pathway. Mutants of Mortierella alpina 1S-4 is a fungus employed for producing arachidonic acid. These mutants produce larger amounts of ETA due to the expression of an ω-3-desaturase gene, typically responsible for the significant production of the more abundant PUFAs. In addition to their inflammatory nature, eicosanoids such as ETA can also contribute to an anti-inflammatory response.