Formation of A Novel Purine Metabolite through CYP3A4 Bioactivation and Glutathione Conjugation

Title:Formation of A Novel Purine Metabolite through CYP3A4 Bioactivation and Glutathione Conjugation

Volume: 10 Issue: 2

Author(s): Julius L. Apuy, Cathie Xiang, Sarah Franc, Sayee G. Hegde, Robert Hubbard, Jingjing Zhao and Mehran F. Moghaddam

Affiliation:

Keywords: Biotransformation, CYP, drug discovery, glutathione, mass spectrometry, metabolite identification, metabolism, novel, NMR, purine, structural elucidation.

Abstract: Background: The study of novel sites of metabolism is important in understanding new mechanisms of biotransformation of a particular moiety by metabolic enzymes. This information is valuable in designing metabolically-stable compounds with drug-like properties. It may also provide insights into the existence of active and reactive metabolites.

Methods: We utilized small scale incubations to generate adequate amounts of the metabolite of interest. After purification, LC-MS/MS and Proton Nuclear Magnetic Resonance (1H-NMR) were utilized to unequivocally assign the novel site of glutathione conjugation on the purine ring system.

Results: A proposed novel site of glutathione conjugation was investigated on a diaminopurine-containing molecule. It was demonstrated that the formation of the glutathione conjugate at the C-6 position of the purine ring system was due to the bioactivation of the compound to a di-imine intermediate by CYP3A4, followed by the nucleophilic addition of glutathione.

Conclusion: S-glutathionylation at C-6 position of a purine was proven unequivocally. This previously unreported mechanism constitutes a novel biotransformation for purines.

Cite this article as:

Apuy L. Julius, Xiang Cathie, Franc Sarah, Hegde G. Sayee, Hubbard Robert, Zhao Jingjing and Moghaddam F. Mehran, Formation of A Novel Purine Metabolite through CYP3A4 Bioactivation and Glutathione Conjugation, Drug Metabolism Letters 2016; 10 (2) . https://dx.doi.org/10.2174/1872312810666160511150558