A New Quaternary Ammonium Cysteine Analogue as a Trapping Reagent for Reactive Metabolites Screening
The novel cysteine-cholamine (Cys-chol) trapping reagent was synthesized by coupling N-(tertbutoxycarbonyl)-
S-trityl-L-cysteine with cholamine in the presence of HBTU (O-(benzotriazol-1-yl)-
N,N,N',N'-tetramethyluronium hexafluorophosphate), and then deprotecting by trifluoroacetic acid. Cys-chol
reagent enhanced the sensitivity of reactive metabolite screening 4 to 20 times without introducing
additional sample preparation or derivatization steps. Retention of Cys-chol conjugates on reversed-phase
column is higher than for respective GSH conjugates which helps in reduction of background interference.
The use of Cys-chol trapping reagent can potentially improve sensitivity and specificity of routine reactive
metabolite screening assay in drug discovery.
Keywords: Bioactivation, cysteine-cholamine, glutathione, LC-MS/MS, metabolism, reactive metabolite screening, trapping
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