[Biosynthesis and functions of eicosanoids. Recent data].

Abstract

Eicosanoids are oxygenated derivatives from 20-carbon polyunsaturated fatty acids. Among these, arachidonic acid is the reference precursor from which most metabolic pathways have been described. These pathways correspond to the biosynthesis of prostanoids with a recent revival interest after the discovery of an inducible form of prostaglandin H synthase, the formation of lipoxygenase products catalyzed by three different enzymes according to the initial carbon position of the oxygenation, and the oxygenation into epoxides and into hydroxy derivatives by the cytochrome P450 family. In addition to these enzyme pathways, the formation of prostaglandin isomers by radical-induced oxygenation and cyclization has been recently described and named isoprostanes. Finally, it is noteworthy to state the interest for two fatty acids of marine origin, namely eicosapentaenoic acid, an arachidonic acid analogue competing with it in different metabolic pathways, and docosahexaenoic acid, precursor of few docosanoids and transcriptional regulator of several activities.