The State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Beijing 100191, China.
Rapid Commun Mass Spectrom. 2010 Nov 30;24(22):3340-50. doi: 10.1002/rcm.4776.
Conyza blinii Le'vl is a medicinal herb used for the treatment of inflammation in Chinese folk medicine. Its major bioactive constituents are triterpene saponins, most of which contain 6-8 sugar residues. In this report, electrospray ionization tandem mass spectrometry fragmentation behaviors of bisdesmosidic triterpene saponins (conyzasaponin A, B, and C) were studied in both positive and negative ion modes with an ion-trap mass spectrometer. In full scan mass spectrometry, these saponins gave predominant M-H and M+Na ions, which determined the molecular weights. In tandem mass spectrometry (MS(n), n = 2-4), the M-H and M+Na ions yielded fragments Y(0α)-H and B(α)+Na, which were diagnostic for the structures of the triterpene skeleton and sugar chains. The structural elucidation was approved by accurate mass data using IT-TOF-MS. An interpretation guideline based on MS(n) (n = 2-4) diagnostic ions was proposed in order to elucidate the chemical structures of unknown triterpene saponins in C. blinii extract. The saponins in C. blinii were separated by liquid chromatography with a methanol/acetonitrile/water solvent system, and then analyzed by ion-trap and IT-TOF mass spectrometers. Based on the interpretation guideline, a total of 35 triterpenoid saponins were tentatively identified. Among them, 15 saponins had been previously reported, and the other 20 saponins were reported from Conyza species for the first time. This study indicates that LC/MS is a powerful technology for the rapid characterization of complicated saponins in herbal extracts.
微毛鸭儿芹是一种药草，在中国民间医学中用于治疗炎症。其主要生物活性成分为三萜皂苷，其中大多数含有 6-8 个糖基。本报告采用离子阱质谱仪，在正负离子模式下研究了双糖苷三萜皂苷（康雅萨宾 A、B 和 C）的电喷雾串联质谱碎裂行为。在全扫描质谱中，这些皂苷主要给出 M-H 和 M+Na 离子，确定了分子量。在串联质谱（MS(n)，n=2-4）中，M-H 和 M+Na 离子产生片段 Y(0α)-H 和 B(α)+Na，这是三萜骨架和糖链结构的特征。通过 IT-TOF-MS 获得的精确质量数据验证了结构解析。提出了基于 MS(n)（n=2-4）诊断离子的解析指南，以阐明微毛鸭儿芹提取物中未知三萜皂苷的化学结构。采用甲醇/乙腈/水溶剂系统的液相色谱法分离微毛鸭儿芹中的皂苷，然后用离子阱和 IT-TOF 质谱仪进行分析。基于该解析指南，共鉴定出 35 种三萜皂苷，其中 15 种以前有报道，其余 20 种是首次从鸭儿芹属中报道。本研究表明 LC/MS 是一种快速鉴定草药提取物中复杂皂苷的强大技术。
