AIM: To investigate pyrrolic metabolites of clivorine andinvolvement of such metabolites in inducing hepatotoxicity.METHODS: Microsomes were prepared from Sprague-Dawleyrats. Clivorine, an otonecine--type pyrrolizidine alkaloid (PA),was incubated with rat microsome in either presence or absence ofglutathione (GSH ). Samples obtained after incubation werecentrifuged, and aliquots of the supernatant were directly analyzedby HPLC--MS and quantified by HPLC--UV method with coupled- AIM: To investigate pyrrolic metabolites of clivorine and involvement of such metabolites in inducing hepatotoxicity. METHODS: Microsomes were prepared from Sprague-Dawleyrats. Clivorine, an otonecine - type pyrrolizidine alkaloid (PA), was incubated with rat microsome in either presence or absence of glutathione (GSH). Samples obtained after incubation were centrifuged, and aliquots of the supernatant were directly analyzedby HPLC - MS and quantified by HPLC - UV method with coupled-