Cytochrome P-450, NADPH-cytochrome P-450 reductase, and glucuronyltransferase were immobilized simultaneously on cyanogen bromide-activated Sepharose from phenobarbital-induced rabbit liver microsomes. The activity of the P-450 system was demonstrated by the N-demethylation of ethylmorphine and the O-demethylation of p-nitroanisole. p-Nitrophenol produced from the oxidation of p-nitroanisole was conjugated to p-nitrophenyl glucuronide, as evidenced by isolation and characterization of the glucuronide by GC/MS.

Animals↗

PubMedDate not supplied

Synthesis of quaternary ammonium-linked glucuronides by rabbit hepatic microsomal UDP-glucuronyltransferase and analysis by fast-atom bombardment mass spectrometry.

The quaternary ammonium-linked glucuronides of tripelennamine and cyproheptadine, important human metabolites of these drugs, were synthesized with an immobilized rabbit hepatic microsomal enzyme system as catalyst. The glucuronide of pyridine was prepared by chemical synthesis. These cationic, thermally labile, quaternary ammonium-linked glucuronides were analyzed by fast-atom bombardment mass spectrometry. The mass spectra contained intense molecular cations and characteristic losses of neutral fragments. The information contained in the spectra was sufficient to characterize the difficult-to-analyze intact quaternary ammonium glucuronides and provide structural information about the aglycon.

Animals↗

PubMedDate not supplied

Iminocyclophosphamide as a chemically reactive metabolite of cyclophosphamide.

Iminocyclophosphamide has been identified among the metabolites produced by incubation of cyclophosphamide with cytochrome P-450 mono-oxygenase immobilized on beaded Sepharose. The reactive imine was trapped by addition of hydrogen cyanide, and the product, 4-cyanocyclophosphamide, was identified by comparison of its chromatographic and mass-spectral properties with those of a synthetic standard. Iminocyclophosphamide was also generated chemically from 4-hydroperoxycyclophosphamide and characterized both by addition of hydrogen cyanide and by reduction with sodium borodeuteride. The synthesis of authentic 4-cyanocyclophosphamide is also reported.

Animals↗

PubMedDate not supplied

Quaternary ammonium-linked glucuronides of amitriptyline, imipramine, and chlorpromazine.

The quaternary ammonium-linked glucuronides of amitriptyline, imipramine, and chlorpromazine were shown to be conjugated in vitro using an immobilized rabbit hepatic microsomal enzyme preparation. It was shown that fast atom bombardment mass spectrometry could be used for direct characterization of these involatile, thermally labile metabolites. The quaternary ammonium-linked glucuronides of amitriptyline and imipramine were demonstrated to be present in urine from patients receiving therapeutic doses of these tricyclic antidepressants.

Amitriptyline↗