UPLC-Q-TOF-MS/MS-guided dereplication of Pulsatilla chinensis to identify triterpenoid saponins

IntroductionTriterpenoid saponins are the major bioactive constituents of Pulsatilla chinensis, playing an important role in various biological activities such as anti-tumour, cognition-enhancing, anti-biosis, anti-inflammatory, hypoglycemic and immunological adjuvant. ObjectiveTo establish a systematic strategy based on ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) for the efficient characterisation and identification of triterpenoid saponins in crude extracts from Pulsatilla chinensis. MethodologyIn this work, the strategy includes two aspects: (1) positive mode: by target screening, we can deduce the aglycone type and the composition of sugar moiety according to the fragment ions; untargeted screening includes four steps, find unknown, formula finder, ChemSpider search and MS/MS identification; (2) negative mode: according to the MS/MS spectra, the composition of sugar chain bonded to C-28 is inferred reasonably. The extract of Pulsatilla chinensis was separated within 60min on a C-18 column and eluted with methanol and water both containing 0.1% formic acid. ResultsAs a result, a total of 22 triterpenoid saponins (11 pairs of isomers) with four aglycone skeletons were tentatively identified or elucidated in crude extracts from Pulsatilla chinensis based on their retention times, the mass spectrometric fragmentation patterns, and MS and MS/MS data. ConclusionThis study provides an efficient analysis strategy to rapidly identify the triterpenoid saponins in Pulsatilla species even in traditional Chinese medicines. Triterpenoid saponins are the major bioactive constituents of Pulsatilla chinensis (P. chinensis). In this work, a systematic strategy based on UPLC-Q-TOF-MS/MS was applied to the efficient characterization and identification of triterpenoid saponins in crude extracts from P. chinensis. As a result, a total of 22 triterpenoid saponins were tentatively identified or elucidated in crude extracts from P. chinensis. This study provides an efficient analysis strategy to rapidly identify the triterpenoid saponins in Pulsatilla species even in traditional Chinese medicines.