Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Rapid Commun Mass Spectrom. 2010 Mar 15;24(5):667-78. doi: 10.1002/rcm.4436.
During the discovery process of novel compounds, it is of significant importance to differentiate novel from known compounds in crude extracts before starting the time-consuming process of purification. Bufadienolides are the main active components of the skin of the toad Bufo bufo gargarizans Cantor (toad skin), an important traditional Chinese medicine. The fragmentation behavior and mass spectra profiles of bufadienolides standards were investigated using ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-Q-TOFMS). Several fragmentation rules were summarized and applied to characterize novel and known bufadienolides in toad skin. Characteristic substituent groups could be identified by both diagnostic ions and their relative abundance. Bufadienolide stereoisomers could be differentiated from positional isomers by comparing fragment abundance profiles. This was used to characterize new stereoisomers for known bufadienolides. A total of 39 bufadienolides were screened out using a systematic method developed in our laboratory. In addition to 19 known bufadienolides, 20 putative novel compounds, including 8 stereoisomers, were characterized. UPLC/Q-TOFMS was demonstrated to be a powerful tool for the characterization of low-abundance bufadienolides in complex samples. This study provides guidelines for the targeted isolation of novel bufadienolides from natural products.
在发现新化合物的过程中，在开始耗时的纯化过程之前，区分粗提物中的新化合物和已知化合物非常重要。蟾蜍素是中国重要的传统中药蟾蜍 Bufo bufo gargarizans Cantor （蟾皮）的主要活性成分。采用超高效液相色谱/电喷雾电离四极杆飞行时间质谱（UPLC/ESI-Q-TOFMS）研究了蟾蜍素标准品的碎片行为和质谱谱图特征。总结了一些碎片规则，并应用于鉴定蟾皮中的新型和已知蟾蜍素。通过特征取代基离子及其相对丰度可以鉴定特征取代基。通过比较碎片丰度谱可以区分蟾蜍素立体异构体和位置异构体。这用于鉴定已知蟾蜍素的新立体异构体。使用我们实验室开发的系统方法筛选出 39 种蟾蜍素。除了 19 种已知的蟾蜍素外，还鉴定了 20 种假定的新型化合物，包括 8 种立体异构体。UPLC/Q-TOFMS 被证明是一种用于鉴定复杂样品中低丰度蟾蜍素的有力工具。本研究为从天然产物中靶向分离新型蟾蜍素提供了指导。
