In vivo oxidation of [9-14C] cyclic fatty acids derived from linolenic acid in the rat

Abstract

-Heating oils and fats may lead to cyclization of polyunsaturated fatty acids, as for example linolenic acid. Cyclohexenyl and cyclopentenyl fatty acids are subsequently present in some edible oils and these are suspected to induce metabolic disorders. In a previous experiment using [1-14 C] labeled molecules, we published that these cyclic fatty acids are beta oxidized to the same extent as linolenic acid, at least for the first cycle of beta oxidation. However, it is possible that the presence of a ring could alter the ability of the organism to fully oxidize the molecule. In order to test this hypothesis, we assessed the oxidative metabolism of cyclic fatty acids carrying a 14 C atom at the vicinity of the ring. For this purpose, rats were force-fed from 1.1 to 1.3 MBq of a representative fraction of dietary cyclohexenyl cyclic fatty acid monomers of [9-14 C] 9-(6-propyl-cyclohex-3-enyl)-non-8-enoic acids and 14 CO 2 production was monitored for 24h. The animals were then necropsied and the radioactivity was determined in different tissues. No consistent radioactivity was recovered as 14 CO 2 24h after administration of the molecules. Sixty percent of the radioactivity was recovered in the urine and 30% in the gastrointestinal tract. By combining our previous data on the oxidation of [1-14 C] cyclic fatty acids and the present results, we suggest that cyclohexenyl fatty acids are first beta oxidized in a similar way as linolenic acid and that the remaining molecule carrying the ring is detoxified and eliminated in the urine and feces. cyclic fatty acid monomers / linolenic acid / oxidation

Dietary cyclic fatty acids derived from linolenic acid do not exhibit intrinsic toxicity in the rat during gestation

“…Based on present data and previous ones showing that oxidation and elimination are powerful processes for excretion of CFAM (Joffre et al, 2004;Bretillon et al, 2006) and considering their low amounts in the diet (Sé bé dio and Grandgirard, 1989;Romero et al, 2000), our data reinforce the assertion that cyclic fatty acids are not a major concern for human safety. Glycemia (mM) Of the pregnant females (at day 20 of gestation) 5.2 6 0.8 (n 5 4) 3.9 6 1.0 (n 5 5) 3.8 6 1.3 (n 5 6) Of the females at day 1 after delivery 6.2 6 1.0 (n 5 4) 5.3 6 1.5 (n 5 4) 4.9 6 1.3 (n 5 4) Of the newborn rats 4.7 6 1.1 (n 5 27) …”

“…When found in the sn-2 position of the triglycerides, CFAM are better and unselectively recovered into the lymph than when esterified in the sn-1 or -3 moieties of the glycerol backbone (Combe et al, 1981;Martin et al, 1997). CFAM are readily oxidized in vivo (Joffre et al, 2004;Bretillon et al, 2006). CFAM were suspected to be the most toxic compounds formed in heated oils (Crampton et al, 1951(Crampton et al, , 1953(Crampton et al, and 1956.…”

Effect of triheptanoin on muscle metabolism during submaximal exercise in horses

“…However, this cannot be confirmed without performing a study in which radiolabeled fatty acids are used. 26 When horses consumed the triheptanoin diet, they had lower plasma concentrations of leucine prior to and throughout SETs than when they consumed the corn oil diet. Because muscle concentrations of amino acids were not measured, it was not possible to determine whether amino acids were metabolized during exercise or served as gluconeogenic precursors following submaximal exercise.…”