Premium
Geometry of conjugated double bonds of CLA isomers in a commercial mixture and in their hepatic 20∶4 metabolites
Author(s) -
Sébédio J. L.,
Juanéda P.,
Grégoire S.,
Chardigny J. M.,
Martin J. C.,
Ginies C.
Publication year - 1999
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-999-0484-3
Subject(s) - chemistry , conjugated linoleic acid , conjugated system , cis–trans isomerism , gas chromatography , double bond , chromatography , structural isomer , oxazoline , hydrazine (antidepressant) , fatty acid , organic chemistry , linoleic acid , catalysis , polymer
Rats were fed a fat‐free diet for 2 wk. After this period, while maintaining the animals on the same diet, the rats were given intragastrically 180 mg per day of a mixture of conjugated linoleic acids (CLA) as triacylglycerols. Gas chromatography‐mass spectrometry (GC‐MS) analyses of this mixture, as well as hydrazine reduction and GC‐MS and GC‐Fourier transform infrared analyses of the resulting monoenes, revealed the presence of two major isomers, the 9 c , 11 t ‐and the 10 t , 12 c ‐18∶2 accompanied by smaller amounts of the 8 t , 10 c and the 11 c ,13 t −18∶2 isomers. Minor quantities of cis,cis and trans,trans conjugated isomers also were detected. The total fatty acid methyl esters from the liver lipids were fractionated by reversed‐phase high‐performance liquid chromatography, and the fraction containing the 20∶4 isomers was further fractionated by silver nitrate thin‐layer chromatography. A band containing two 20∶4 conjugated isomers was submitted to hydrazine reduction and the resulting monoenes analyzed by GC‐MS as dimethyl‐oxazoline derivatives. The two conjugated isomers were tentatively identified as 5 c ,8 c ,11 c ,13 t –20∶4 and 5 c ,8 c ,12 t ,14 c −20∶4. These could be formed by desaturation and elongation of the 9 c ,11 t ‐and 10 t ,12 c −18∶2 present in the commerical CLA mixture.