Arachidonic acid

Arachidonic acid chemical structure.

Arachidonic acid or eicosatetraenoic acid (IUPAC: (5Z,8Z,11Z,14Z)-5,8,11,14-Eicosatetraenoic acid, often abbreviated AA) is a polyunsaturated fatty acid of the omega-6 series, formed by a 20-carbon chain with four cis double bonds at positions 5, 8, 11 and 14, which is why it is acid 20:4(5,8,11,14).

Its structural chemical formula is:

The presence of double bonds supposes several potential sites of enzymatic or chemical oxidation that, together with a subsequent rearrangement, allows the formation of different lipids with different biological activities.

This arachidonic acid is part of the phospholipids of cell membranes, and is the precursor of eicosanoid biosynthesis. Arachidonic acid can be synthesized from linoleic acid, one of the essential fatty acids required by most mammals. However, some of these have little or no ability to convert linoleic acid to arachidonic acid, so arachidonic acid becomes an essential part of their diet. Since vegetables contain little or no arachidonic acid, such animals are necessarily predators; the cat is a characteristic example.

Arachidonic acid oxidative pathways

The two main enzymatic oxidative routes of the arachidonic are:

• Vía de la 5-lipooxigenasa (LOX), whose main products are leucotrienos, HETE and lipoxins.
• Cyclooxigenous path (COX), whose main products are prostaglandins, prostacyclines and tromboxans.

These two enzymes do not act on arachidonic acid esters, so the free fatty acid must first be released from the membrane phospholipids, which occurs thanks to phospholipases.