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Arachidonic acid (AA, sometimes ARA) is an omega-6 fatty acid 20:4(?-6). It is the counterpart to the saturated arachidic acid found in peanut oil, (L. arachis – peanut.)[1]
Chemistry
In chemical structure, arachidonic acid is a carboxylic acid with a 20-carbon chain and four cis double bonds; the first double bond is located at the sixth carbon from the omega end.
Some chemistry sources define 'arachidonic acid' to designate any of the eicosatetraenoic acids. However, almost all writings in biology, medicine and nutrition limit the term to all-cis 5,8,11,14-eicosatetraenoic acid.
Biology
Arachidonic acid is a polyunsaturated fatty acid that is present in the phospholipids (especially phosphatidylethanolamine, phosphatidylcholine and phosphatidylinositides) of membranes of the body's cells, and is abundant in the brain.
It is also involved in cellular signaling as a second messenger.
It is the source of several other molecules with specific roles, as described in the next section.
Synthesis and cascade
Arachidonic acid is freed from phospholipid molecule by the enzyme phospholipase A2, which cleaves off the fatty acid.
Arachidonic acid is a precursor in the production of eicosanoids:
The production of these derivatives and their action in the body are collectively known as the arachidonic acid cascade; see essential fatty acid interactions for more details.
Essential fatty acid
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Arachidonic acid in the human body comes from dietary animal sources—meat, eggs, dairy—or is synthesized from linoleic acid.
Arachidonic acid is one of the essential fatty acids required by most mammals. Some mammals lack the ability to—or have a very limited capacity to—convert linoleic acid into arachidonic acid, making it an essential part of their diet. Since little or no arachidonic acid is found in plants, such animals are obligate carnivores; the cat is a common example.[2][3]
See also
References
- ^ "Dorland's Medical Dictionary – 'A'". Retrieved on 2007-01-12.
- ^ MacDonald M, Rogers Q, Morris J (1984). "Nutrition of the domestic cat, a mammalian carnivore". Annu Rev Nutr 4: 521–62. doi:10.1146/annurev.nu.04.070184.002513. PMID 6380542. Retrieved on 2007-02-09.
- ^ Rivers J, Sinclair A, Crawford M (1975). "Inability of the cat to desaturate essential fatty acids". Nature 258 (5531): 171–3. doi:10.1038/258171a0. PMID 1186900.
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