Use of doubly protonated molecules in the analysis of cathedulins in crude extracts of khat (Catha edulis) by liquid chromatography/serial mass spectrometry
Use of doubly protonated molecules in the analysis of cathedulins in crude extracts of khat (Catha edulis) by liquid chromatography/serial mass spectrometry
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DOI：
10.1002/rcm.1085
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发表时间：
2003-01-01
影响因子：
2
通讯作者：
Houghton, PJ
中科院分区：
文献类型：
--
作者：
Kite, GC;Ismail, M;Houghton, PJ
利用液相色谱/质谱（LC/MS）对新鲜阿拉伯茶（Catha edulis）粗甲醇提取物进行分析，发现其含有62种cathedulin生物碱（与已发表的15种结构相比）。许多cathedulins在电喷雾电离后产生双质子化分子，双质子化与单质子化的比例可以通过调节电喷雾毛细管位置和源条件来控制。通过选择双质子化物质进行串联质谱分析（MS/MS），可以使用离子阱质谱仪在低于离子阱质谱分析[m +H]（+）所允许的m/z值下观察单电荷产物离子。这些光谱在阐明cathedulins的酰化模式方面特别有价值，其中MS/MS分析[M+H]（+）导致大量中性物质的损失，从而产生一个低于离子捕获下限的小单电荷片段。62种cathedulin中大多数的酰化模式都是通过质谱分析得到的，其中一个质量为1001 Da的主要未报道的cathedulin的数据表明，它属于一个具有cathate二内酯桥而不是evoninate桥的新cathedulin类。版权所有：John Wiley Sons， Ltd。
Analysis of crude methanolic extracts of fresh khat (Catha edulis) by liquid chromatography/mass spectrometry (LC/MS) revealed the presence of 62 cathedulin alkaloids (compared with 15 published structures). Many cathedulins generated doubly protonated molecules following electrospray ionisation and the ratio of doubly to singly protonated species could be manipulated by adjusting the electrospray capillary position and source conditions. By selecting the doubly protonated species for serial mass spectrometric analysis (MS/MS), it was possible to use an ion trap mass spectrometer to observe singly charged product ions at lower m/z values than ion trap MS/MS analysis of [M+H](+) would have allowed. These spectra were particularly valuable in elucidating the acylation patterns of cathedulins where MS/MS analysis of [M+H](+) resulted in loss of a large neutral species to yield a small singly charged fragment below the lower limit for ion trapping. Acylation patterns for most of the 62 cathedulins are proposed from mass spectrometric analysis, and the data obtained for a major unreported cathedulin of mass 1001 Da suggest that it belongs to a new group of cathedulins having a cathate dilactone bridge but not an evoninate bridge. Copyright (C) 2003 John Wiley Sons, Ltd.