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|Chemical Name||icosa-5,8,11,14-tetraenoic acid|
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|Functional Taxonomy||Not Available|
|Nutritional Taxonomy||Not Available|
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Arachidonic acid is a polyunsaturated, essential fatty acid. It is found in animal and human fat as well as in the liver, brain, and glandular organs, and is a constituent of animal phosphatides. It is formed by the synthesis from dietary linoleic acid. Arachidonic acid mediates inflammation and the functioning of several organs and systems either directly or upon its conversion into eicosanoids. Arachidonic acid in cell membrane phospholipids is the substrate for the synthesis of a range of biologically active compounds (eicosanoids) including prostaglandins, thromboxanes, and leukotrienes. These compounds can act as mediators in their own right and can also act as regulators of other processes, such as platelet aggregation, blood clotting, smooth muscle contraction, leukocyte chemotaxis, inflammatory cytokine production, and immune function. Arachidonic acid can be metabolized by cytochrome p450 (CYP450) enzymes to 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs), their corresponding dihydroxyeicosa-trienoic acids (DHETs), and 20-hydroxyeicosatetraenoic acid (20-HETE). The production of kidney CYP450 arachidonic acid metabolites is altered in diabetes, pregnancy, hepatorenal syndrome, and in various models of hypertension, and it is likely that changes in this system contribute to the abnormalities in renal function that are associated with many of these conditions. Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 position of membrane glycerophospholipids to liberate arachidonic acid (PMID: 12736897, 12736897, 12700820, 12570747, 12432908)
A polyunsaturated omega-6 essential fatty acid (C20:4). Arachidonic acid is present in cell membranes, esterified into the phospholipids. It is formed in the body by synthesis from dietary linoleic acid (C18:2, also an essential fatty acid) and is a precursor in the biosynthesis of eicosanoids: prostaglandins, thromboxanes, and leukotrienes. It is found in animal and human fat as well as in the liver, brain, and glandular organs, and is a constituent of animal phosphatides.
Essential fatty acids play a role in many metabolic processes. Evidence suggests that low levels of essential fatty acids or wrong balance between different types of essential fatty acids may be an important factor in some diseases. Metabolites of arachidonic acid (eicosanoids) have a range of functions in the body, mostly related to inflammation and the central nervous system. The eicosanoids derived from arachidonic acid mostly promote of inflammation. Omega-3 fatty acids like EPA (C20:5) can compete with arachidonic acid for activity of the cyclooxygenas and lipoxygenase enzymes. Therefore, increased omega-3 fatty acid intake results in decreased synthesis of eicosanoids derived from arachidonic acid leading to softening of the pro-inflammatory effect of arachidonic acid. Also, arachidonic acid itself can interact with transcription factors in the nucleus and influence transcription of e.g. cytokines.
In order for arachidonic acid to be metabolised, it has to be released from the phospholipd in the cell membrane. This release is catalyzed by phospholipase A2 and can take place in response to a variaty of inflammatory signals. The free fatty acid is then oxygenated and further modified, yielding eicosanoids. Oxidation by cyclooxygenases (COX1, COX2, COX3) results in prostaglandins and thromboxanes. Oxidation by lipoxygenases results in leukotrienes.
Diseases / Conditions Related to Nutrition
- Gestational diabetes mellitus
Eicosanoids, the metabolites of arachidonic acid, are potent bioactive molecules with a role in inflammation. Since inflammation is involved in many nutrition related diseases, arachidonic acid is linked to many mutrition related diseases, e.g. cancer, atherosclerosis, allergy, obesity.
Prostaglandins (a group of eicosanoids) are thought to be involved in carcinogenesis. Inhibition of cyclooxygenase enzymes by non-steroidal anti-inflammatory drugs (NSAIDs), e.g. aspirin, is a possible way of chemoprevention. Links to PubMed abstracts: Prostaglandins and cancer, Pharmacological intervention of cyclooxygenase-2 and 5-lipoxygenase pathways. Impact on inflammation and cancer
Arachidonic acid and atherosclerosis: Monocyte cyclooxygenase-2 activity: a new therapeutic target for atherosclerosis?, The 5-lipoxygenase pathway in arterial wall biology and atherosclerosis
Arachidonic acid and obesity: Arachidonic acid maldistribution in obesity
Arachidonic acid and allergy: Arachidonic acid signaling in pathogenesis of allergy: therapeutic implications
Arachidonic acid and hypertension: Role of cytochrome P450 metabolites of arachidonic acid in hypertension
Arachidonic acid and depression: Evidence for a role of the arachidonic acid cascade in affective disorders: a review
Associated decreased protein/metabolite profile
Associated increased protein/metabolite profile
Other (Monogenic) Disorders
Arachidonic acid can be synthesized from dietary linoleic acid, which is present in vegetable oils and animal fats.