In vitro hepatic metabolism of cinchona antimalarials by hamster enzymes

Cinchona alkaloids [quinidine and cinchonine] were incubated with aldehyde oxidase and microsomal monooxygenases from hamster liver. Reversed-phase HPLC method was used to separate quinidine and cichonine from their metabolites. Characterisation of the metabolites arising from aldehyde oxidase by infrared and mass spectral analysis, exhibited that quinidine and cinchonine were oxidised to the corresponding 2'-quinolones. In vitro microsomal metabolites of quinidine were identified as 2'-quinidinone and O-desmethylquinidine. Incubation of cinchonine with microsomal enzymes showed that no metabolites were generated