The use of mass spectrometry in the study of chemically-reactive drug metabolites. Application of MS/MS and LC/MS to the analysis of glutathione- and related S-linked conjugates of N-methylformamide.
The S-(N-methylcarbamoyl) derivatives of glutathione, cysteine and N-acetylcysteine, the S-linked conjugates derived from a reactive metabolite of N-methylformamide (NMF), were studied in mice dosed with an equimolar mixture of NMF and deuterium-labelled NMF. Following preparation of N-benzyloxycarbonyl derivatives in aqueous media, the title conjugates were isolated, purified as their methyl esters and subjected to analysis by fast atom bombardment mass spectrometry (FAB/MS), fast atom bombardment tandem mass spectrometry (FAB/MS/MS) or thermospray liquid chromatography/mass spectrometry (TSP LC/MS). Characteristic isotope clusters in the FAB or TSP mass spectra facilitated recognition of drug metabolites, while constant neutral loss (89 u) and daughter ion scanning tandem mass spectrometry (MS/MS) experiments provided unique structural information on the conjugates of interest. It is concluded that the combined use of stable isotopes, aqueous-phase derivatization and contemporary mass spectrometric techniques represents a powerful approach for the analysis of glutathione adducts and related S-linked conjugates of chemically-reactive drug metabolites.
Baillie
T A
TA
Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle 98195.
Pearson
P G
PG
Rashed
M S
MS
Howald
W N
WN
D000111:Acetylcysteine / Q000032:analysis; D000818:Animals; D001646:Bile / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D003545:Cysteine / Q000032:analysis; D005559:Formamides / Q000032:analysis* / Q000378:metabolism; D005978:Glutathione / Q000032:analysis; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D016339:Spectrometry, Mass, Fast Atom Bombardment
D005559:Formamides; D005978:Glutathione; D003545:Cysteine; D000111:Acetylcysteine; C002950:methylformamide