In vivo formation of codeinone-glutathione adduct: isolation and identification of a new metabolite in the bile of codeine-treated guinea pig.

Codeinone-glutathione adduct (CO-GSH) in the bile of guinea pigs given a subcutaneous injection of codeine was isolated and identified. Synthesized authentic CO-GSH was characterized by the mass and nuclear magnetic resonance spectra and used as the standard sample. The metabolite was isolated by preparative high-performance liquid chromatography on a C18 column. The fractions containing the conjugated metabolite were purified using Sep-Pak C18 cartridges. For further purification of the metabolite CO-GSH, a Radial Pak CN column was used. Structure assignment of the metabolite was then performed by fast-atom-bombardment mass spectrometry and 500 MHz Fourier-transform-NMR spectrometric analysis and identified as S-[4,5-epoxy-3-methoxy-17-methyl-6-oxomorphinan-(8S)-yl] glutathione.