Effects of trans-10, cis-12 conjugated linoleic acid and cognates on apolipoprotein B secretion in HepG2 cells

Abstract

Conjugated linoleic acid (CLA) has been shown to decrease apolipoprotein B (apoB) secretion in HepG2 cells. The purpose of this study was to determine the activity of individual CLA isomers—and to test cognates that are structurally related to CLA—with regard to apoB secretion. Trans-10, cis-12 CLA decreased apoB secretion whereas cis-9, trans-11, cis-9, cis-11, trans-9, trans-11, and the chloride, alcohol, or amide forms of CLA had no effect on apoB secretion. Trans-9, cis-12 octadecadienoic acid had no effect whereas cis-9, cis-12 octadecadienoic acid (linoleic acid) enhanced apoB secretion. Among 18-carbon monounsaturated fatty acids tested, only trans-10 octadecenoic acid decreased apoB secretion. Trans-11, trans-12, trans-13, cis-9 , cis-11, and cis-13 octadecenoic acids increased apoB secretion whereas trans-9 and cis-12 octadecenoic acids were without effect. None of the 20-carbon compounds tested or cis-12 octadecen-10-ynoic acid had an effect on apoB secretion. Conjugated nonadecadienoic acid decreased apoB secretion whereas cis-10, cis-13 nonadecadienoic acid did not. The reduction of apoB secretion by CLA mixture is caused by the unique structural features of trans-10, cis-12 CLA. A trans double bond at the 10th position appears to be a key structure involved in the inhibition of apoB secretion.