Arachidonic acid

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Structural formula
Structural formula of arachidonic acid
General
Surname Arachidonic acid
other names
  • (5 Z , 8 Z , 11 Z , 14 Z ) -Eicosa-5,8,11,14-tetraenoic acid ( IUPAC )
  • ( Z , Z , Z , Z ) -Eicosa-5,8,11,14-tetraenoic acid
  • (all- Z ) -Eicosa-5,8,11,14-tetraenoic acid
  • 20: 4 (ω − 6) ( lipid name )
Molecular formula C 20 H 32 O 2
Brief description

colorless, clear liquid

External identifiers / databases
CAS number 506-32-1
EC number 208-033-4
ECHA InfoCard 100.007.304
PubChem 444899
ChemSpider 392692
DrugBank DB04557
Wikidata Q407699
properties
Molar mass 304.46 g mol −1
Physical state

liquid

density

0.922 g cm −3

Melting point

−49.5 ° C

boiling point

169-171 ° C (20 Pa )

solubility

practically insoluble in water, readily soluble in non-polar solvents (benzene)

Refractive index

1.4824 (20 ° C)

safety instructions
GHS labeling of hazardous substances
no GHS pictograms
H and P phrases H: no H-phrases
EUH: 019
P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Arachidonic acid is a four-fold unsaturated fatty acid in the group of omega-6 fatty acids . Polyenoic acid is one of the isolenic acids , as the four cis double bonds are separated by a methylene group (CH 2 ). Their common name is derived from the fully saturated arachidic acid , which is produced by the hydrogenation of arachidonic acid.

Occurrence and biological importance

Arachidonic acid is only rarely found in plants. B. in the real black cumin ( Nigella sativa ) and various other plants only in small quantities. It does not occur in cooking oils or only in traces.

Arachidonic acid is used in most animal organisms - exceptions are e.g. B. Domestic cats - synthesized from the essential omega-6 fatty acid linoleic acid via the intermediate stages γ-linolenic acid (GLA) and dihomo-γ-linolenic acid (DGLA) or taken in through food. As a component of lipids such as phospholipids in esterified (physiologically inactive) form, it is mainly located in the cell membranes. It can be released by the enzyme phospholipase A 2 (often from 1,2-diacylglycerols , DAG ) and thereby biologically activated.

Cytosolic arachidonic acid is metabolized by enzymes from different groups , producing derivatives that act as signaling molecules . Although their effects are not uniform, arachidonic acid itself is considered to be more inflammatory . So inhibit cortisol and vitamin E , the phospholipase and can inflammatory processes such. B. in joint diseases such as activated osteoarthritis and other forms of arthritis . In this context, the lowest possible intake or synthesis of arachidonic acid seems to be very desirable in terms of health in most cases. In the case of inflammatory autoimmune diseases (especially in multiple sclerosis (MS), but also in autoimmune thyroid disorders and rheumatism ), a diet that is low in arachidonic acid is also often recommended. So far there is no reliable evidence for the effectiveness of special diets. This connection may also be confirmed in the future with regard to ulcerative colitis . According to an evaluation as part of the EPIC study, ulcerative colitis occurred more frequently in people who had a higher intake of linoleic acid , even if no direct diet recommendations can be drawn from these study results.

The biological effect of the arachidonic acid derivatives is not limited to inflammatory reactions. It is very extensive, sometimes also contradicting itself, and is therefore dealt with under the individual metabolites.

Metabolism

Arachidonic acid has (simplified) three ways of further metabolism:

The arachidonic acid metabolism leads to metabolites with partially contradicting properties. An increase in cyclooxygenase-2 has a fever-inducing effect , while an increase in epoxidizing CYPs directly and indirectly suppresses or limits fever in various ways. Acetylsalicylic acid and ibuprofen not only inhibit the cyclooxygenase pathway, but also induce the epoxygenase pathway, whose metabolic products in turn inhibit the cyclooxygenases more strongly than these drugs. Metabolism by CYPs does not always lead to anti-inflammatory effects: the 20-HETE formed by hydroxylating CYPs has a pro-inflammatory effect.

Arachidonic acid in foods

Arachidonic acid- containing glycerides can be found in numerous foods. Their proportion is particularly high in pork lard (1700 mg per 100 g), pork liver (870 mg per 100 g), egg yolk (297 mg per 100 g), tuna (280 mg per 100 g) and liver sausage (230 mg per 100 g) . In addition, a high-sugar diet can lead to increased hormonally controlled infiltration into the cells. Vegetable oils with a high concentration of linoleic acid and products derived from them contain hardly any arachidonic acid themselves, but their ingredients contribute to its formation. Since omega-3 and omega-6 fatty acids compete for the same enzymes, the biosynthesis of anti-inflammatory substances from omega-3 fatty acids is also reduced.

Individual evidence

  1. ↑ a b c Entry on arachidonic acid. In: Römpp Online . Georg Thieme Verlag, accessed on June 20, 2014.
  2. ↑ a b Data sheet arachidonic acid from Acros, accessed on November 21, 2007.
  3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-228.
  4. ↑ Arachidonic acid data sheet from Sigma-Aldrich , accessed on May 25, 2011 ( PDF ).
  5. ↑ 5,8,11,14-Eicosatetraenoic acid from PlantFA Database, accessed October 27, 2017.
  6. ↑ Michael S. Hand (ed.), Hans Joachim Oslage (red.): Clinical dietetics for small animals. 4th edition, Volume 1, Schlütersche 2004, ISBN 978-3-87706-893-9 , p. 376.
  7. ↑ Stefan Schwarz u. a .: Unconventional therapies for multiple sclerosis: benefit unclear. In: Deutsches Ärzteblatt Cologne. 102.30, 2005, p. 1678 f.
  8. ↑ W. Kozak et al .: Molecular mechanisms of fever and endogenous antipyresis. In: Ann. NY Acad. Sci. 917: 2000, pp. 121-134, PMID 11268336 .
  9. ↑ M. Laniado-Schwartzman et al .: 20-Hydroxyeicosatetraenoic acid stimulates nuclear factor-kappaB activation and the production of inflammatory cytokines in human endothelial cells. In: J. Pharmacol. Exp. Ther. 324 (1): 2008, pp. 103-110, PMID 17947496 .

Web links

Wiktionary: arachidonic acid  - explanations of meanings, word origins, synonyms, translations