In vitro oxidation of pyrazinamide and allopurinol by rat liver aldehyde oxidase

Biochem Pharmacol. 1993 Sep 14;46(6):975-81. doi: 10.1016/0006-2952(93)90661-f.


Aldehyde oxidase was purified about 120-fold from rat liver cytosol by sequential column chromatography using diethylaminoethyl (DEAE) cellulose, Benzamidine-Sepharose 6B and gel filtration. The purified enzyme was shown as a single band with M(r) of 2.7 x 10(5) on polyacrylamide gel electrophoresis (PAGE) and M(r) of 1.35 x 10(5) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Using this purified enzyme, in vitro conversion of allopurinol, pyrazinamide and pyrazinoic acid was investigated. Allopurinol and pyrazinamide were oxidized to oxypurinol and 5-hydroxy-pyrazinamide, respectively, while pyrazinoic acid, the microsomal deamidation product of pyrazinamide, was not oxidized to 5-hydroxypyrazinoic acid. The apparent Km value of the enzyme for pyrazinamide was 160 microM and that for allopurinol was 1.1 mM. On PAGE, allopurinol- or pyrazinamide-stained band was coincident with Coomassie Brilliant Blue R 250-stained band, respectively. These results suggest that aldehyde oxidase may play a role in the oxidation of allopurinol to oxypurinol and that of pyrazinamide to 5-hydroxypyrazinamide with xanthine dehydrogenase which can oxidize both allopurinol and pyrazinamide in vivo. The aldehyde oxidase may also play a major role in the oxidation of allopurinol and pyrazinamide in the subgroup of xanthinuria patients (xanthine oxidase deficiency) who can oxidize both allopurinol and pyrazinamide.

MeSH terms

  • Aldehyde Oxidase
  • Aldehyde Oxidoreductases / antagonists & inhibitors
  • Aldehyde Oxidoreductases / isolation & purification
  • Aldehyde Oxidoreductases / metabolism*
  • Allopurinol / metabolism*
  • Animals
  • Benzamidines / pharmacology
  • In Vitro Techniques
  • Liver / enzymology*
  • Male
  • Oxidation-Reduction
  • Oxypurinol / metabolism
  • Pyrazinamide / analogs & derivatives
  • Pyrazinamide / metabolism*
  • Rats
  • Rats, Wistar
  • Triazines / pharmacology


  • Benzamidines
  • Triazines
  • 5-hydroxypyrazinamide
  • Pyrazinamide
  • BOF 4272
  • Allopurinol
  • Aldehyde Oxidoreductases
  • Aldehyde Oxidase
  • Oxypurinol
  • benzamidine