title: Formation of A Novel Purine Metabolite through CYP3A4 Bioactivation and Glutathione Conjugation.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  S-glutathionylation at C-6 position of a purine was proven unequivocally. This previously unreported mechanism constitutes a novel biotransformation for purines.
authors.forename: Julius L
authors.initials: JL
authors.lastname: Apuy
authors.forename: Cathie
authors.initials: C
authors.lastname: Xiang
authors.forename: Sarah
authors.initials: S
authors.lastname: Franc
authors.forename: Sayee G
authors.initials: SG
authors.lastname: Hegde
authors.forename: Robert
authors.initials: R
authors.lastname: Hubbard
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Celgene Corporation, 10300 Campus Point Dr, Suite 100, San Diego, CA 92121, USA. mmoghadd@celgene.com.
authors.forename: Mehran F
authors.initials: MF
authors.lastname: Moghaddam
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D004285:Dogs; D005978:Glutathione / Q000378:metabolism*; D000882:Haplorhini; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D051379:Mice; D011687:Purines / Q000378:metabolism*; D051381:Rats; D053719:Tandem Mass Spectrometry
chemical_list: D011687:Purines; D051544:Cytochrome P-450 CYP3A; D005978:Glutathione