arakidonihapon

Arakidonihapon (arachidonic acid) is a polyunsaturated omega-6 fatty acid with 20 carbon atoms and four cis double bonds (20:4, n-6). It is a principal component of membrane phospholipids in many tissues and serves as a key precursor for signaling molecules.

Phospholipase A2 releases arachidonic acid from membrane phospholipids under cellular stimulation. Once free, it is metabolized by cyclooxygenases (COX) to form prostaglandins and thromboxanes, by lipoxygenases (LOX) to generate leukotrienes, or by cytochrome P450 enzymes to produce epoxides and other metabolites. These compounds regulate inflammation, hemostasis, and vascular tone.

Dietary sources include animal products such as meat, eggs, and dairy, where it occurs as a component of phospholipids and triglycerides. The body can also synthesize arachidonic acid from linoleic acid (18:2 n-6) via desaturation and elongation; this process involves delta-6 desaturase, elongase, and delta-5 desaturase.

Arachidonic acid plays roles in growth, reproduction, and immune function, and is particularly important in infants. In adults it supports normal cellular signaling but excessive levels can contribute to chronic inflammation if not counterbalanced by anti-inflammatory mediators such as those derived from omega-3 fatty acids.

Medical relevance includes the use of nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit COX enzymes to reduce prostaglandin synthesis. Nutrition strategies aim to balance omega-6 and omega-3 intake to modulate eicosanoid production and inflammatory responses.