General description
Arachidonic acid (AA) is a polyunsaturated ϖ fatty acid constituent of the phospholipids of cell membranes. Structurally, it is a 20-carbon chain that contains four cis double bonds, which allow the free acid form of AA to be an insoluble oil; this can be converted to the water-soluble sodium salt form within the normal physiological pH range. Arachidonic acid is metabolized by multiple enzymes to yield various metabolites; AA and its metabolites play important roles in a variety of biological processes, including signal transduction, smooth muscle contraction, chemotaxis, cell proliferation and differentiation and apoptosis.
Application
Arachidonic acid is used in assays to measure activity of oxidizing enzymes, such as cyclooxygenase, as well as in assays to determine platelet inhibition in whole blood. Arachidonic acid has been demonstrated to bind to the a subunit of G protein and inhibit the activity of Ras GTPase-activating proteins (GAPs), to have a role in the development and progression of prostate cancer, and to enhance formation of lipid bodies in human mast cells.
Biochem/physiol Actions
Arachidonic acid (ARA) is a vital component of biological cell membranes, providing them with the necessary fluidity and flexibility crucial for the functioning of all cells, particularly in the nervous system, skeletal muscle, and immune system. Free ARA regulates the activity of ion channels, various receptors, and enzymes, both through activation and inhibition. ARA undergoes reacylation/deacylation cycles within cell membranes, maintaining its concentration at a low level and restricting its availability for oxidation. Metabolites resulting from ARA oxidation do not initiate inflammation but contribute to it, and more significantly, they generate mediators crucial for resolving inflammation and promoting wound healing. Released arachidonic acid (AA) reacts with molecular oxygen nonenzymatically, through oxidative stress, and enzymatically through the action of oxygenase enzymes. AA is oxidized to prostaglandins and thromboxanes by at least two cyclooxygenase (COX) isoforms, to leukotrienes and lipoxins by lipoxygenases, and to epoxyeicosatrienoic acids via cytochrome p450-catalyzed metabolism. Cellular uptake of arachidonic acid is energy-dependent and involves protein-facilitated transport across the plasma membrane.
Disclaimer
The sodium salts of arachidonic acid are very sensitive to oxidation and will turn yellow and deteriorate rapidly in air. They are packaged under vacuum in sealed ampules. Once opened the product must be used quickly or transferred into an inert atmosphere (dry argon) as soon as possible.
