In vitro metabolism of cinchona antimalarials by hamster enzymes

ABSTRACT

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