Arachidonic acid (AA) is an unsaturated omega-6 fatty acid constituent of the phospholipids of cell membranes. Phospholipase A2 releases AA from the membrane phospholipids in response to inflammation. AA is subsequently metabolized to prostaglandins and thromboxanes by at least two cyclooxygenase (COX) isoforms, to leukotrienes and lipoxins by lipoxygenases, and to epoxyeicosatrienoic acids via p450-catalyzed metabolism. AA and its metabolites play important roles in a variety of biological processes, including signal transduction, contraction, chemotaxis, and cell proliferation, differentiation and apoptosis. AA has been demonstrated to bind to the α subunit of G protein and inhibit the activity of Ras GTPase-activating proteins (GAPs). Cellular uptake of AA is energy dependent and involves protein-facilitated transport across the plasma membrane.
