Comprehensive profiling and characterization of quassinoids from the seeds of Brucea javanica via segment and exposure strategy coupled with modified mass defect filter

Quassinoids, the predominant constituents in the seeds of Brucea javanica (BJ), have gained an increasing interest over the past decades since the discovery of their extensive biological activities. In the present study, a method based on the segment and exposure strategy coupled with two mass spectrometer data acquisition techniques was firstly developed and validated for comprehensive profiling of quassinoids in the seeds of BJ via high-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (HPLC-QTOF/MS). The segment and exposure strategy could significantly improve the detection efficiency for trace quassinoids in the seeds of BJ. Furthermore, the five-point screening approach based on modified mass defect filter (MDF) and the visual isotopic ion technique could rapidly screen the precursor ions of interest. The fragmentation behavior of quassinoids was systematically investigated, and a total of 148 quassinoids including 86 potentially new ones were unambiguously or tentatively identified in the seeds of BJ. Collectively, our results demonstrate that the integrated strategy reported in this study has considerable potential for rapid screening of natural compounds especially for the trace ones in herbal medicines.