Rapid screening and identification of sesquiterpene lactones in Kudiezi injection based on high-performance liquid chromatography coupled with linear ion trap-orbitrap mass spectrometry

Sesquiterpene lactones are considered as the major active compounds in Kudiezi injection in virtue of their special structures and activities. Herein, an analytical method was developed for rapid screening and identification of sesquiterpene lactones in Kudiezi injection using high-performance liquid chromatography coupled with linear ion trap-orbitrap mass spectrometry (HPLC-LTQ-Orbitrap) in negative ion mode. First, two sesquiterpene lactone reference standards were analyzed to obtain their characteristic ESI-MS/MS fragmentation patterns. Second, based on extracted ion chromatography (EIC) data-mining method and characteristic fragmentation pathways analysis, sesquiterpene lactones in Kudiezi injection were rapidly screened and identified. Finally, an important parameter Clog P was adopted to discriminate the isomers of sesquiterpene lactones. As a result, 50 sesquiterpene lactones were characterized, including 9 sesquiterpene lactone aglycones, 39 sesquiterpene lactone glycosides, and 2 amino acid-sesquiterpene lactone conjugates. Among them, 13 compounds were tentatively identified as new compounds. The results demonstrated that the established method would be a rapid, effective analytical tool for screening and identification of sesquiterpene lactones in the complex system of natural medicines.