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Title: APPLICATION OF DEUTERIUM-LABELED FATTY ACIDS FOR INVESTIGATION OF METABOLISM AND ENDOGENOUS SYNTHESIS OF CONJUGATED LINOLEIC ACIDS IN HUMANS

Author
item Adlof, Richard
item EMKEN, EDWARD - RETIRED USDA EMPLOYEE

Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2003
Publication Date: 5/20/2003
Citation: ADLOF, R.O., EMKEN, E. APPLICATION OF DEUTERIUM-LABELED FATTY ACIDS FOR INVESTIGATION OF METABOLISM AND ENDOGENOUS SYNTHESIS OF CONJUGATED LINOLEIC ACIDS IN HUMANS. ANNUAL MEETING AND EXPO OF THE AMERICAN OIL CHEMISTS SOCIETY. 2003. p. 5.

Interpretive Summary:

Technical Abstract: Fatty acid isomers labeled with deuterium atoms (2H-FA) have been synthesized via a combination of acetylenic and/or Wittig coupling reactions or from seed oil FA precursors such as santalbic acid (9a,11t-18:2) with Lindlar catalyst and 2H2 gas. Non-radioactive, 2H-FA isomers can be used as tracers in human studies and their incorporation and metabolism followed by gas chromatography/mass spectrometry. They are often purified by silver ion chromatography and then converted to and fed as free fatty acids, FA ethyl esters or as triacylglycerols (TAG). In one study, 11-trans- and 11-cis-octadecenoic acids (plus 9c-18:1 and 9c,12c-18:2), each FA labeled with differing numbers of 2H atoms, were fed to an adult male and their conversion to 2H-labeled conjugated linoleic acid (2H-CLA; 9c,11t-18:2) confirmed. The 11-trans isomer was found to be converted to CLA at a rate 10-fold higher than the 11-cis isomer (to 9c,11c-18:2), but no evidence was found for conversion of 10-cis- or 10-trans-18:1 to 10,12-18:2, nor for isomerization of 9c,12c-18:2 to 9c,11t-18:2. A mixture of 2H-labeled 9c-18:1, 9c,12c-18:2 and two 2H-CLA isomers (10t,12c-18:2-2H4 and 9c,11t-18:2-2H6) was fed to adult women. CLA isomers were 20-25% less well-absorbed than 9c-18:1 or 9c,12c-18:2, with a selective discrimination/ accumulation for 10t,12c- and 9c,11t-18:2 similar to that observed for cis and trans-18:1 positional isomers. Accumulation of 9c,11t-18:2-2H6 vs.10t,12c-18:2-2H4 in the various plasma lipid classes varied widely by class (9% to 73%) and by isomer, the latter demonstrated by the 4x higher incorporation of 10t,12c-18:2-2H4 vs 9c,11t-18:2-2H6 in 1-position of 1-acyl phosphatidylcholine vs. the 2-3x higher incorporation of 9c,11t-18:2-2H6 vs 10t,12c-18:2-2H4 in cholesterol esters. Metabolism of the 2H-CLA isomers was low (<0.5%) except for 6c,10t,12c-18:3 (5%; from 10t,12c-18:2). Similar studies have been done using rat models and in a number of culture cell lines.