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Fatty acid


DATA No : DFA0159 INFORMANT : Tetsuyuki Kobayashi

NAME : cis-9, cis-12-Octadecadienoic acid

COMMON NAME: Linoleic acid
SYMBOL: LA / C18:2n-6 / C18:2w6
FORMULA: C18H32O2 MOL.WT (average) : 280.445


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BIOLOGICAL ACTIVITY
There are two groups of essential fatty acids for mammals, the n-6 (or w6) and the n-3 (or w3). Linoleic acid (LA) is one of the n-6 essential fatty. Animals deficient in LA show the growth retardation, skin lesions, reproductive failure, fatty liver and polydipsia (Ref. 2009/2010). Dietary supplementation of either linoleate, g-linoleate or arachidonate prevents such symptoms completely. Its physiological functions appear to be mediated mainly through the hormone-like eicosanoids (prostaglandins, leukotriens and thromboxanes et al.) derived from arachidonic acid which is biosynthesized from LA. LA is also shown to be involved in control of the water impermeability of the skin and regulation of cholesterol synthesis and transport.
PHYSICAL AND CHEMICAL PROPERTIES
MELTING POINT:-5degC

BOILING POINT:229degC to 230degC at 16mmHg

REFRACTIVE INDEX:1.4711 at 20degC

OPTICAL ROTATION:

DENSITY:d4-20 0.9031

SOLUBILITY:soluble in acetone, alcohol, ether and petroleum ether.(Ref. 0193)(Ref. 0351)(Ref. 0378)(Ref. 0409)(Ref. 0410)
SPECTRAL DATA
UV SPECTRA:

IR SPECTRA:

NMR SPECTRA:

MASS SPECTRA:

OTHER SPECTRA:
CHROMATOGRAM DATA
Gas liquid chromatogram
[Chromatogram 0001] (provided by Dr. Akiko Horiuchi).
SOURCE
Constituent of the essential fatty acids (vitamin F) and of various microorganisms; oils of cottonseed, soybean, peanut, corn, sunflower and poppy seed.
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) Although plants synthesize and store linoleic acid and a-linolenic acid as well as saturated and monounsaturated fatty acids in grains, the proportions of these fatty acids in different vegetable oils differ greatly. Safflower and sunflower oil contain high levels of linoleate, while perilla and linseed oil are rich in a-linolenic acid.
GENETIC INFORMATION

NOTE

REFERENCES
[0193]
AUTHOR:Gaudemaris, M. deand Arnaud. P.
TITLE:
JOURNAL:Bull. Soc. Chim. Fr.
VOL: PAGE : 315 - (1962)
[TOP]

[0351]
AUTHOR:Matthews, N. L., et al.
TITLE:
JOURNAL:J. Amer. Chem. Soc.
VOL:63 PAGE : 1064 - (1941)
[TOP]

[0378]
AUTHOR:Nicolaides, N., and Laves, F.
TITLE:
JOURNAL:J. Amer. Chem. Soc.
VOL:80 PAGE : 5752 - (1958)
[TOP]

[0409]
AUTHOR:Raphael, R. A.
TITLE:
JOURNAL:J. Chem. Soc. London
VOL: PAGE : 2100 - (1950)
[TOP]

[0410]
AUTHOR:Raphael, R. A., and Sondheimer, F.
TITLE:
JOURNAL:Nature (London)
VOL:165 PAGE : 235 - (1950)
[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]

[2009]
AUTHOR:A.E. Hansen, H.F. Wiese, A.N. Boelsche, at al.
TITLE:Role of linoleic acid in infant nutrition.
JOURNAL:Pediatrics
VOL:31 PAGE : 171 -192 (1963)
[TOP]

[2010]
AUTHOR:Paulsrud, J. R., Pensler, L., Whitten, C. F., Stewart, S., and Holman, R. T.
TITLE:Essential fatty acid deficiency in infants induced by fat-free intravenous feeding PubMed ID:4626563
JOURNAL:Am J Clin Nutr.
VOL:25 PAGE : 897-904 (1972)
[TOP]

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