Negative-ion chemical-ionization mass spectrometry of aclarubicin analogs and characterization of two metabolites in man.

Aclarubicin and seven analogs have been characterized by negative-ion chemical-ionization mass spectrometry. The method is highly sensitive (requires 1-10 ng) because of the stable semiquinone radical anions that are produced by resonance electron capture of thermal electrons. Ions in the spectra correspond to the intact molecule (M), M-H2O, aglycone, aglycone-O, and aglycone-2H2O. In addition, ions corresponding to the sequential loss of carbohydrate groups are exhibited in the spectra of compounds with di- and tri-saccharides. Two aclarubicin analogs were isolated from a patient's plasma and were found to be bisanhydroaklavinone, F, and one or both of the epimeric reduction products of the L-cinerulose carbonyl, M1 and N1.