Arachidonic Acid (AA)
Arachidonic acid is a polyunsaturated fatty acid with four cis double bonds, which are the sources of its flexibility and give it the capacity to react with molecular oxygen. It is present in the membrane of the body's cells, and is a precursor in the production of eicosanoids: the prostaglandins, thromboxanes, prostacyclin and the leukotrienes.
Arachidonic acid is the keystone essential fatty acid at the origin of the arachidonic acid cascade. It is converted by cyclooxygenase, lipoxygenase, and epoxygenase enzymes into more than one hundred fifty different potent primary autacoid metabolites in species ranging from fungi to plants to mammals. Arachidonic acid is stored in tissue phospholipids in esterified form, where it comprises a small but critically controlled percentage of the polyunsaturated fatty acid pool. Arachidonic acid content is frequently measured by the saponification of the lipid fraction followed by methyl esterification and gas chromatographic analysis of the resulting FAME (fatty acid methyl ester) compounds. Arachidonic acid methyl ester can also be incorporated into dietary regimens or fed to cultured cells as a source of exogenous arachidonate.