Dihomo-gamma-linolenic acid

Dihomo-γ-linolenic acid

Names
Other names cis,cis,cis-8,11,14-Eicosatrienoic acid DGLA
Identifiers
CAS Number	1783-84-2
ChemSpider	4444199
Jmol interactive 3D	(canonical): Image (isomeric): Image
PubChem	5280581
UNII	FC398RK06S
InChI InChI=1S/C20H34O2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18-19-20(21)22/h6-7,9-10,12-13H,2-5,8,11,14-19H2,1H3,(H,21,22)/b7-6-,10-9-,13-12- Key: HOBAELRKJCKHQD-QNEBEIHSSA-N InChI=1/C20H34O2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18-19-20(21)22/h6-7,9-10,12-13H,2-5,8,11,14-19H2,1H3,(H,21,22)/b7-6-,10-9-,13-12- Key: HOBAELRKJCKHQD-QNEBEIHSBE
SMILES (canonical): CCCCCC=CCC=CCC=CCCCCCCC(=O)O (isomeric): CCCCC\C=C/C\C=C/C\C=C/CCCCCCC(=O)O
Properties
Chemical formula	C20H34O2
Molar mass	306.49 g·mol^−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Dihomo-γ-linolenic acid (DGLA) is a 20-carbon ω−6 fatty acid. In physiological literature, it is given the name 20:3 (ω−6). DGLA is a carboxylic acid with a 20-carbon chain and three cis double bonds; the first double bond is located at the sixth carbon from the omega end. DGLA is the elongation product of γ-linolenic acid (GLA; 18:3, ω−6). GLA, in turn, is a desaturation product of linoleic acid (18:2, ω−6). DGLA is made in the body by the elongation of GLA, by an efficient enzyme which does not appear to suffer any form of (dietary) inhibition. DGLA is an extremely uncommon fatty acid, found only in trace amounts in animal products.^[1][2]

Biological effects

The eicosanoid metabolites of DGLA are:

• Series-1 thromboxanes (thromboxanes with 1 double-bond), via the COX-1 and COX-2 pathways.
• Series-1 prostanoids, via the COX-1 and COX-2 pathways.^[3]
• A 15-hydroxyl derivative that blocks the transformation of arachidonic acid to leukotrienes.^[4]

All of these effects are anti-inflammatory. This is in marked contrast with the analogous metabolites of arachidonic acid (AA), which are the series-2 thromboxanes and prostanoids and the series-4 leukotrienes. In addition to yielding anti-inflammatory eicosanoids, DGLA competes with AA for COX and lipoxygenase, inhibiting the production of AA's eicosanoids.

Taken orally in a small study, DGLA produced antithrombotic effects.^[5] Supplementing dietary GLA increases serum DGLA, as well as serum AA levels.^[6] Cosupplementation with GLA and EPA lowers serum AA levels by blocking Δ-5-desaturase activity, while also lowering leukotriene synthesis in neutrophils.^[7]

Borage is a rich source of γ-linolenic acid—the dietary precursor to DGLA.

See also

• Essential fatty acid

References

1. Horrobin, D. F., 1990a. Gamma linolenic acid. Rev. Contemp. Pharmacother. 1, 1-45
2. Huang, Y.-S. and Mills, D. E. (Eds.), 1996. Gamma-linolenic acid metabolism and its roles in nutrition and medicine. AOCS Press, Champagne, Illinois, 319 pp.
3. Fan, Yang-Yi and Robert S. Chapkin (9 September 1998). "Importance of Dietary γ-Linolenic Acid in Human Health and Nutrition". Journal of Nutrition 128 (9): 1411–4. PMID 9732298. Retrieved 2007-10-16.
4. Belch, Jill JF and Alexander Hill (January 2000). "Evening primrose oil and borage oil in rheumatologic conditions". Retrieved February 12, 2006.
5. Kernoff PB, Willis AL, Stone KJ, Davies JA, McNicol GP (1977). "Antithrombotic potential of dihomo-γ-linolenic acid in man". British Medical Journal 2 (6100): 1441–1444. doi:10.1136/bmj.2.6100.1441. PMC 1632618. PMID 338112.
6. Johnson MM, Swan DD, Surette ME, et al. (1997). "Dietary supplementation with γ-linolenic acid alters fatty acid content and eicosanoid production in healthy humans". J. Nutr. 127 (8): 1435–44. PMID 9237935.
7. Barham JB, Edens MB, Fonteh AN, Johnson MM, Easter L, Chilton FH (August 2000). "Addition of eicosapentaenoic acid to gamma-linolenic acid-supplemented diets prevents serum arachidonic acid accumulation in humans". J. Nutr. 130 (8): 1925–31. PMID 10917903.