Vaccenic acid
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| trans -Vaccenic acid | ||||||||||
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| Surname | Vaccenic acid | |||||||||
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| Molecular formula | C 18 H 34 O 2 | |||||||||
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| properties | ||||||||||
| Molar mass | 282.46 g mol −1 | |||||||||
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| density |
0.8563 g cm −3 (70 ° C) ( trans ) |
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| Melting point |
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| Refractive index |
1.4499 (60 ° C) ( trans ) |
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| 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 | ||||||||||
Vaccenic acid is a naturally occurring chemical compound from the group of unsaturated fatty acids . The name is derived from the Latin word vacca (" cow "). It exists in two isomeric forms, which differ in the arrangement of the substituents on the double bond . The trans -Vaccensäure is found in nature in fats from ruminants, in fish oil , blood plasma , as well as microorganisms such as Lactobacillus types, and Escherichia coli .
trans -Vaccenic acid
The trans or (E) -vaccenic acid belongs to the trans fatty acids . It is produced by the hydrogenation of polyunsaturated fatty acids such as α-linolenic acid in the rumen of ruminants .
Trans -Vaccenic acid is contained in small amounts in fats from ruminants, for example 2.3% in butter .
cis -vaccenic acid
The cis - or (Z) -vaccenic acid, the asclepic acid, has a significantly lower melting point and has a hemolytic effect. In addition to blood plasma, it also occurs in various animal tissues, in natural fats and fish oil. It is also found in the lipids of the cell membrane of many bacteria , for example 31% of Lactobacillus plantarum (formerly known as Lactobacillus arabinosus ) and 16% of Lactobacillus casei . In E. coli , vaccenic acid makes up the majority of the unsaturated acids present. In Agrobacterium tumefaciens, too , cis -vaccenic acid predominates as a fatty acid in the lipids, its proportion is 68%. In many bacteria, cis -vaccenic acid is the precursor to lactobacillic acid in the biosynthesis of fatty acids .
It also occurs naturally in the seed fats of many plants, e.g. B. in the guaraná ( Paullinia cupana ) to about 30% as well as in the ginkgo ( Ginkgo biloba ) and in the pulp of the persimmon ( Diospyros kaki ) up to about 30% or in that of the grapefruit ( Citrus paradisi ) and also the orange ( Citrus sinensis ) approx. 15–20%.
proof
The detection and determination of the content of vaccenic acid is usually carried out by gas chromatography of the methyl ester; In addition, the unsaturated isomers can be separated using silver nitrate thin-layer chromatography.
Individual evidence
- ↑ a b 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. 3-402.
- ↑ trans-11- Octadecenoic acid at Lipidbank.
- ↑ a b c d Entry on vaccenic acid. In: Römpp Online . Georg Thieme Verlag, accessed on March 5, 2011.
- ↑ a b data sheet trans-Vaccenic acid from Sigma-Aldrich , accessed on April 25, 2011 ( PDF ).
- ↑ a b data sheet cis-Vaccenic acid from Sigma-Aldrich , accessed on April 25, 2011 ( PDF ).
- ↑ F. Destaillats, E. Buyukpamukcu, P.-A. Golay, F. Dionisi and F. Giuffrida: Letter to the Editor: Vaccenic and Rumenic Acids, A Distinct Feature of Ruminant Fats. In: Journal of Dairy Science. 88 (449), 2005, doi : 10.3168 / jds.S0022-0302 (05) 72705-3 .
- ↑ a b c Wissenschaft-Online-Lexika: Entry on vaccenic acid in the Lexikon der Biochemie. Retrieved March 6, 2011.
- ↑ trans-vaccenic acid at ETH Zurich.
- ↑ K. Hofmann, RA Lucas, SM Sax: The chemical nature of the fatty acids of Lactobacillus arabinosus. In: The Journal of biological chemistry. Volume 195, No. 2, April 1952, pp. 473-485, PMID 14946156 .
- ↑ K. Hofmann, SM Sax: The chemical nature of the fatty acids of Lactobacillus casei. In: The Journal of biological chemistry. Volume 205, No. 1, November 1953, pp. 55-63, PMID 13117883 .
- ↑ K. Hofmann, F. Tausig: On the identity of phytomonic and lactobacillic acids; a reinvestigation of the fatty acid spectrum of Agrobacterium (Phytomonas) tumefaciens. In: The Journal of biological chemistry. Volume 213, No. 1, March 1955, pp. 425-432, PMID 14353943 .
- ^ DW Grogan, JE Cronan: Cyclopropane ring formation in membrane lipids of bacteria. In: Microbiology and molecular biology reviews: MMBR. Volume 61, No. 4, December 1997, pp. 429-441, PMID 9409147 , PMC 232619 (free full text).
- ↑ TK Lim: Edible Medicinal And Non-Medicinal Plants. Volume 6: Fruits , Springer, 2013, ISBN 978-94-007-5627-4 , p. 82.
- ↑ (Asclepic acid; cis-Vaccenic acid) from PlantFA Database, accessed October 27, 2017.
- ↑ B. Breuer, T. Stuhlfauth, HP Fock: Separation of fatty acids or methyl esters including positional and geometric isomers by alumina argentation thin-layer chromatography. In: J. of Chromatogr. Science. 25: 302-306 (1987) PMID 3611285 .