STUDIES ON THE METABOLISM OF CIS,TRANS ISOMERS OF METHYL LINOLEATE AND LINOLENATE.

SUMMARY Studies were made of the group composition of the lipids and of the fatty acid components in each class of lipids in the livers of rats fed a fat-free diet or diets supplemented with methyl linoleate (cis-9, cis-12-octadecadienoate); methyl cis-9, trans-12-octadecadienoate; and methyl linolenate, which contained 300/, of the double bonds in the trans configuration (designated as “cis,trans”-methyl linolenate because it consisted of a mixture of all-cis and cis,trans isomers). The conversion of methyl cis-9, trans-12-octadecadienoate to an isomer of arachidonic acid, believed to be cis-5,cis-8,cis-ll,trans-lPeicosatetraenoic acid, and of ‘LCiS,trand’-methyl linolenate to polyenoic acids containing trans unsaturation in rats is reported. The metabolism of trans acids in relation to the nutritional requirements of the rat for essential fatty acids is discussed. 4,7,10,13-Eicosatetraenoic acid was found in the liver phospholipids of rats fed a fat-free diet and, to a lesser extent, in the liver phospholipids of a group of rats receiving a supplement of methyl linoleate.