Two dihydropyrrolizine alkaloid metabolites isolated from mouse hepatic microsomes in vitro.

The in vitro mouse hepatic microsomal metabolism of the macrocyclic pyrrolizidine alkaloid senecionine was studied for additional metabolites. Using previously developed HPLC systems plus a preparative system, two additional dihydropyrrolizine metabolites have been identified from the microsomal enzyme system of mice. The metabolites 1-hydroxymethyl-7-methoxy-6,7-dihydro-5H-pyrrolizine (methoxydehydroretronecine) and 1-formyl-7-hydroxy-6,7-dihydro-5H-pyrrolizine (hydroxydanaidal) have not been heretofore isolated from mouse microsomal enzyme systems. The metabolite dehydroretronecine which had previously been isolated from rat hepatic microsomes, was not detected while senecic acid, 19-hydroxysenecionine, and senecionine N-oxide were again present.