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Fatty acid


DATA No : DFA0180 INFORMANT : Tetsuyuki Kobayashi

NAME : cis-6, cis-9, cis-12-Octadecatrienoic acid

COMMON NAME: g-Linolenic acid
SYMBOL: C18:3n-6 / C18:3w6 / gLnn / gLnA
FORMULA: C18H30O2 MOL.WT (average) : 278.430


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BIOLOGICAL ACTIVITY
There are two groups of essential fatty acids, the n-6 (or w6) and the n-3 (or w3). g-linolenic acid is n-6 fatty acids. Essential fatty acid deficiency causes skin lesion and growth retardation. Dietary supplementation of either linoleate, g-linoleate or arachidonate prevents such symptoms completely. The n-6 essential fatty acids have at least four roles (Ref. 2014): 1) Modulation of membrane structure. 2) Formation of short-lived giologically active molecules. Oxygenated derivatives of g-linolenic acid is a Arachidonic acid may have a role in the regulation of cell devision in cancer and other cells. There are other bioactive substance, PGE1 and 15-OH-dihomogamma-linolenic acid which are both formed from g-linolenic acid after its rapid elongation to dihomogamma-linolenic acid. 3) Control of the water impermeability of the skin. 4) Regulation of cholesterol synthesis and transport.
PHYSICAL AND CHEMICAL PROPERTIES
MELTING POINT:-11.3 to -11degC

BOILING POINT:125degC at 0.05mmHg

REFRACTIVE INDEX:1.4800 at 20degC

OPTICAL ROTATION:

DENSITY:d4-20 0.9164

SOLUBILITY:soluble in acetone, ether, methylalcohol and petroleum ether.(Ref. 0352)(Ref. 0383)(Ref. 0415)
SPECTRAL DATA
UV SPECTRA:

IR SPECTRA:

NMR SPECTRA:

MASS SPECTRA:

OTHER SPECTRA:
CHROMATOGRAM DATA

SOURCE
Isolated from seeds of Oenothera biennis and O. lamarckiana (evening primroses); drying oils. A minor component of many animal lipids.
CHEMICAL SYNTHESIS

METABOLISM
Linoleic acid (18:2n-6) is synthesized from oleic acid (18:1n-9) by desaturation of D12-desaturase, and a-linolenic acid (18:3n-3) is formed from linoleic acid by desaturation reaction of D15-desaturase. Since both D12- and 15-desaturases are present in plant cells but not in animal cells, linoleic and a-linolenic acid are not biosynthesized in animal cells in vivo. When ingested by animals, linoleic acid is desaturated, elongated to form g-linolenic acid (18:3n-6), dihomo-g-linolenic acid (20:3n-6), arachidonic acid (20:4n-6) and adrenic acid (22:4n-6). Docosapentaenoic acid (22:5n-6) is synthesized from adrenic acid in significant amounts only under conditions of prolonged n-3 fatty acid deficiency.
No interconversion between the n-6 and n-3 series in mammals. Nutritionally, it is important to note that different foods contain different proportions of n-6/n-3 and therefore the n-6/n-3 ratio in tissue lipids change significantly depending on the choice of foods.(Ref. 2003)
GENETIC INFORMATION

NOTE

REFERENCES
[0352]
AUTHOR:McCutcheon, J. W., et al.
TITLE:
JOURNAL:Oil Soap (Chicago)
VOL:18 PAGE : 9 - (1941)
[TOP]

[0383]
AUTHOR:Osbond, J. M., and Wickens, J. C.
TITLE:
JOURNAL:Chem. Ind. (London)
VOL: PAGE : 1288 - (1959)
[TOP]

[0415]
AUTHOR:Riley, J. P.
TITLE:
JOURNAL:J. Chem. Soc. London
VOL: PAGE : 2728 - (1949)
[TOP]

[2003]
AUTHOR:Okuyama, H., Kobayashi, T., and Watanabe, S.
TITLE:Dietary fatty acids--the N-6/N-3 balance and chronic elderly diseases. Excess linoleic acid and relative N-3 deficiency syndrome seen in Japan PubMed ID:9246358
JOURNAL:Prog Lipid Res.
VOL:35 PAGE : 409-457 (1996)
[TOP]

[2014]
AUTHOR:D.F. Horrobin
TITLE:Nutritional and Medical Importance of Gamma-linolenic Acid. PubMed ID:1334266
JOURNAL:Prog. Lipid Res.
VOL:31 PAGE : 163 -194 (1992)
[TOP]

Last updated June 19, 2007. Copyright © 1989-2007 Japanese Conference on the Biochemistry of Lipids (JCBL). All rights reserved.