Characterization of alkaloids in Sophora flavescens Ait. by high-performance liquid chromatography–electrospray ionization tandem mass spectrometry

Sophora flavescens Ait., a well-known Chinese herbal medicine, is widely used in clinical practice for the treatment of viral hepatitis, cancer, gastrointestinal hemorrhage, and skin diseases. This paper is the first report on a method based on the combined use of high-performance liquid chromatography, photodiode array detection, and electrospray ionization tandem mass spectrometry for the comprehensive and systematic separation and characterization of bioactive alkaloids in Sophora flavescens Ait. A total of 22 constituents were identified on the basis of the extracted ion chromatograms for different [M+H]+ ions of the alkaloids present in S. flavescens Ait. Among these, 5 constituents were unambiguously identified by comparing the experimental data on their retention times and MSn spectra with those of the authentic compounds, and 17 other constituents were tentatively identified on the basis of their MSn fragmentation behaviors and/or molecular weight information from literatures. Furthermore, some characteristic fragmentation pathways of the alkaloids in S. flavescens Ait. were detected and examined. This information may be useful for characterizing the bioactive alkaloids present in S. flavescens Ait. and for possible applications in formulations.