A comparative study on the effect of cis (oleic, linoleic) and trans (elaidic, linoelaidic) fatty acids on the in vitro prostaglandin biosynthesis in human blood platelets from (1-14C) arachidonic acid.

Dietary fatty acids affect the synthesis and thus ultimate availability of prostaglandin precursors. During processing of edible fats a significant portion of the naturally occurring cis fatty acids is changed to the respective trans isomers. Trans fatty acids could have a wide variety of effects including their effect on prostaglandin synthesis. A comparative study on the effect of cis (oleic and linoleic) fatty acids and their corresponding trans isomers (elaidic and linoelaidic acids) on the in vitro prostaglandin biosynthesis in human blood platelets was made. Linoleic acid (0.5, 1.0 mM) showed the same effect on the various arachidonic acid (AA) metabolites as reported earlier by us, that is, increased generation of prostaglandins and thromboxanes and reduced amounts of HHT and HETE (26). Linoelaidic acid at these two concentrations had the same effect but to a lesser extent. Both linoleic and linoelaidic acids at 0.25 mM concentration reduced TxB2 formation. Oleic and elaidic acids (0.5, 1.0 mM) decreased the formation of TxB2 though not significantly. With oleic acid, the results in respect of other AA metabolites were similar to those reported by us earlier (26). MDA was reduced significantly in the presence of linoleic, linoelaidic and oleic acids; cis isomers being more effective. In the presence of linoleic and linoelaidic acids, prostaglandin endoperoxides were reduced significantly; there was no change in the presence of oleic and elaidic acids. Thus fatty acids seem to affect the platelet cyclo-oxygenase activity; this being more pronounced in the case of cis fatty acids compared to their trans isomers. Reduction in cyclo-oxygenase activity also depends upon the number of double bonds in the acids.