Gas chromatographic—mass spectrometric characterisation of some novel hydroxyeicosatetraenoic acids formed on incubation of arachidonic acid with microsomes from induced rat livers

The biotransformation of arachidonic acid by rat liver microsomes from both control animals and animals pretreated with known inducers of cytochrome P-450 isoenzymes has been studied using a combination of reversed- and normal-phase high-performance liquid chromatography and combined gas chromatography—electron-impact mass spectrometry. The metabolite profiles observed were found to be dependent upon the inducing agent. Five metabolites were identified, namely 16-, 17-, 18-, 19- and 20-hydroxylated arachidonic acids. Of these the 16- and 17-isomers have not been reported as products of arachidonic acid metabolism by any biological system and the 18-isomer has not been reported as a product of liver metabolism.