Abstract

The occurrence of boldione metabolites conjugated with cysteine and N-acetylcysteine in human urine was evaluated. Methods based on precursor ion scan of the protonated aminoacid (m/z 122 and m/z 164 for cysteine and N-acetylcysteine respectively) and neutral losses of the aminoacids (121 Da and 163 Da for cysteine and N-acetylcysteine respectively) were applied for the open detection of conjugates. Results for urine samples collected before and after boldione administration were compared. Using this approach, 24 metabolites (eleven conjugates with cysteine and thirteen conjugated with N-acetylcysteine) were detected. The metabolites were characterized by mass spectrometry and their potential structures were proposed based on this information. The structures of nine of these metabolites were confirmed by the synthesis of the conjugates. According to these results, a metabolic pathway for boldione involving this type of conjugation was presented. Up to our knowledge this is the first time that cysteine conjugates are presented for exogenous anabolic androgenic steroids and the first report of N-acetylcysteine conjugates for steroids. Verf.-Referat