Prostanoids are a family of biologically active substances that derived from eicosanoid fatty acids. The three main groups of prostanoids are the prostaglandins, prostacyclins and thromboxanes. all of them mediators in numerous pathophysiological processes, including the inflammatory immune response, platelet aggregation, vascoconstriction, vasodilation, gastrointestinal motility and neuronal activity.
The synthesis of prostaglandins is carried out by the action of enzymes prostaglandin-endoperoxide synthase, better known as cyclooxygenase (COX). Prostacyclins are synthesized from prostaglandins by the action of prostacyclin synthase. Thromboxanes are also synthesized from prostaglandins by the enzyme thromboxane-A synthase.
The main prostanoid precursor is arachidonic acidan omega-6 fatty acid, but there are also prostanoids that are synthesized from eicosapentaenoic acid and dihomo-gamma-linolenic acid, two Omega-3 fatty acids.
Prostanoid synthesis is increased under certain circumstances, such as tissue damage, release of prostanoids from neighboring cells, or the presence of various chemical factors. In these situations, a cascade of reactions is activated that culminates in the release of arachidonic acid from the cytoplasmic membranes, the main reservoir of this fatty acid in the body.
The action of cyclooxygenase on arachidonic acid produces a highly reactive peroxide and from it prostaglandin H (PGH) is formed. From this molecule all other prostanoids are synthesized. Lipoxygenase (LOX) can also act on arachidonic acid, a synthesis route that produces leukotrienes, HETE and lipoxins, another family of substances other than prostanoids.
Prostanoids, their receptors and their synthesis pathways are therapeutic target of many drugs. For example, aspirin and other NSAIDs (nonsteroidal anti-inflammatory drugs) act by blocking prostaglandin synthesis by inhibiting the action of COX. These drugs are considered anti-prostanoids, but there are also drugs that mimic the action of prostanoids and are used to treat conditions such as glaucoma, erectile dysfunction, stomach ulcers or pulmonary hypertension; for example, epoprostenol is a synthetic prostaglandin used to treat various types of pulmonary arterial hypertension.
Arachidonic acid (omega-6) can be synthesized from linoleic acid (omega-3), the latter considered essential. The balance between both types of fatty acids in the diet influences the prevention of numerous diseases, especially those related to the cardiovascular system, such as hypertension and atherosclerosis, and those related to chronic inflammatory processes, such as rheumatoid arthritis and even cancer . It has also been associated with improved brain function, improved symptoms of depression, and increased intellectual performance.
The beneficial health effects are associated with a diet higher in omega-3 fatty acids, which displace omega-6 and compete for COX enzymes, resulting in less prostanoid production. The main sources of omega-3 are fatty fish, mainly blue Fishand vegetable sources such as seed and nut oils. Some omega-3s are even used as drugs; For example, eicosapentaenoic acid, better known as EPAis used in the pharmacological treatment of certain types of hyperlipidemia.