eikosanoider

Eikosanoider, commonly known as eicosanoids in English, are a family of bioactive lipids derived from polyunsaturated 20-carbon fatty acids, principally arachidonic acid. They are produced on demand in nearly all tissues and act locally as autocrine and paracrine mediators with short half-lives.

Biosynthesis occurs when phospholipase A2 releases arachidonic acid from membrane phospholipids, and then multiple enzymatic routes convert it: the cyclooxygenase (COX) pathway yields prostaglandins and thromboxanes; the lipoxygenase (LOX) pathway yields leukotrienes and lipoxins; cytochrome P450 enzymes generate epoxyeicosatrienoic acids (EETs).

Major groups include prostaglandins (PGE2, PGI2, PGD2, PGF2α), thromboxanes (TXA2), leukotrienes (LTA4, LTB4, LTC4, LTD4, LTE4) and lipoxins. Epoxyeicosatrienoic acids (EETs) are also considered eicosanoids; many act via G protein–coupled receptors to modulate vascular tone, platelet function, immune responses, and smooth muscle activity.

Physiological roles are diverse and context dependent, including regulation of inflammation, pain and fever, maintenance of gastric mucosa, renal function, bronchial tone, and hemodynamics. They coordinate local responses to injury and infection and participate in resolving inflammation.

Clinically, eicosanoid signaling is targeted by drugs. Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit COX enzymes, reducing prostaglandin synthesis. Corticosteroids suppress phospholipase A2 activity. Leukotriene pathway inhibitors and receptor antagonists are used for asthma and allergies. Prostaglandin analogs and prostacyclin treatments are used for gastric protection, erectile dysfunction, and pulmonary arterial hypertension.

Because eicosanoids act locally and are rapidly metabolized, they are challenging to measure in vivo, but modern analytical methods quantify individual species in tissues and fluids to study roles in physiology and disease.