Lipids

, Volume 34, Issue 12, pp 1319–1325

Geometry of conjugated double bonds of CLA isomers in a commercial mixture and in their hepatic 20∶4 metabolites

  • J. L. Sébédio
  • P. Juanéda
  • S. Grégoire
  • J. M. Chardigny
  • J. C. Martin
  • C. Ginies
Article

DOI: 10.1007/s11745-999-0484-3

Cite this article as:
Sébédio, J.L., Juanéda, P., Grégoire, S. et al. Lipids (1999) 34: 1319. doi:10.1007/s11745-999-0484-3

Abstract

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 9c, 11t-and the 10t, 12c-18∶2 accompanied by smaller amounts of the 8t, 10c and the 11c,13t−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 5c,8c,11c,13t–20∶4 and 5c,8c,12t,14c−20∶4. These could be formed by desaturation and elongation of the 9c,11t-and 10t,12c−18∶2 present in the commerical CLA mixture.

Abbreviations

AgNO3-TLC

silver nitrate thin-layer chromatography

CLA

conjugated litoleic acid

DMOX

dimethyl-oxazoline

FAME

fatty acid methyl ester

GC-FTIR

gas-liquid chromatography coupled with Fourier transform infrared spectroscopy

GC-MS

gas-liquid chromatography coupled with mass spectrometry

GLC

gas-liquid chromatography

HPLC

high-performance liquid chromatography

Copyright information

© AOCS Press 1999

Authors and Affiliations

  • J. L. Sébédio
    • 1
  • P. Juanéda
    • 1
  • S. Grégoire
    • 1
  • J. M. Chardigny
    • 1
  • J. C. Martin
    • 1
  • C. Ginies
    • 2
  1. 1.Unité de Nutrition LipidiqueINRADijon CédexFrance
  2. 2.Laboratoire de Recherches sur les ArômesINRADijon CédexFrance