METABOLISM OF DIETARY PETROSELINIC ACID - A DEAD-END METABOLITE OF DESATURATION CHAIN ELONGATION REACTIONS/

The role of the position of the cis-double bond in monounsaturated fat ty acids on their metabolic behavior was studied by feeding rats triac ylglycerols containing high levels of petroselinic (Delta(6)-cis-octad ecenoic acid, n-12 18:1) or oleic acid (Delta(9)-cis-octadecenoic acid , n-9 18:1). Petroselinic acid from dietary triacylglycerols (coriande r oil) was extensively esterified into lipids of rat liver. Chain elon gation of petroselinic acid to Delta 8-cis-eicosenoic acid (n-12 20:1) as well as chain shortening to Delta(4)-cis-hexadecenoic acid (n-12 1 6:1) were the major metabolic reactions, whereas products resulting fr om desaturation/chain elongation of petroselinic acid were not detecta ble, suggesting that this fatty acid is a dead-end metabolite of this pathway. In contrast, distinctly detectable proportions of desaturatio n/chain elongation products of oleic acid, e.g. Delta(5,8,11)-all cis- eicosatrienoic acid (n-9 20:3, Mead's acid) were found in the liver li pids of rats fed a high-oleic sunflower oil. Dietary petroselinic acid inhibited desaturation/chain elongation reactions of Linoleic acid (D elta(9,12)-cis, cis-octadecadienoic acid, n-6 18:2) which resulted in reduced levels of arachidonic acid (Delta(5,8,11,14)-all cis-eicosatet raenoic acid, n-6 20:4) in Liver lipids. It is envisaged that petrosel inic acid having a Delta(6)-double bond mimics a product of Delta(6)-d esaturase and thus induces pseudo-product mediated inhibition of the d esaturase. Copyright (C) 1996 Elsevier Science Inc.