Effects of conjugated linoleic acid isomers on the hepatic microsomal desaturation activities in vitro

The influence of individual conjugated linoleic acid (CLA) isomers on the D elta 6 desaturation of linoleic and alpha-linolenic acids and on the Delta 9 desaturation of stearic acid was investigated in vitro, using rat liver m icrosomes. The Delta 6 desaturation of 18:2n-6 was decreased from 23 to 38% when the ratio of 9cis,11trans-18:2 to 18:2n-6 increased from 0.5 to 2. Th e compound 10trans, 12cis-18:2 exhibited a similar effect on ly at the high est concentration. The Delta 6 desaturation of a-linolenic acid was slightl y affected by the presence of CLA isomers. The sole isomer to induce an inh ibitory effect on the Delta 9 desaturation of stearic acid was 10 trans, 12 cis-18:2.