Department of Pharmaceutical Sciences, Universidade Federal de Santa Catarina, Campus Universitário-Trindade, Florianópolis, Florianópolis, SC, CEP, 88040-970, Brazil.
Department of Chemistry, Universidade Federal de Santa Catarina, Campus Universitário-Trindade, Florianópolis, Florianópolis, SC, CEP, 88040-900, Brazil.
J Mass Spectrom. 2019 Nov;54(11):915-932. doi: 10.1002/jms.4433. Epub 2019 Dec 17.
Sesquiterpene lactones (SL) have been reported with various biological effects. Among the described SL skeletons, hirsutinolide and glaucolide have not been extensively studied by mass spectrometry (MS), especially how to distinguish them in organic matrices. Thus, this paper reports (1) a strategy of their differentiation based on MS behavior during the ionization and (2) a proposal of the fragmentation pattern for both SL-subtypes. ESI(+)-HRMS data of four isolated SL (hirsutinolides 1 and 3; glaucolides 2 and 4) were recorded by direct and UPLC water-sample combined injections. These analyses revealed that hirsutinolides and glaucolides formed [M+Na] ion during the operation of the direct MS injection, and ([M+Na] and [M+H-H O] ) and [M+H] ions were respectively observed for hirsutinolides and glaucolides during the operation of combined UPLC water and sample MS injection. Computational simulations showed that the complex hirsutinolide (1)-Na formed with a lower preparation energy compared with the complex glaucolide (2)-Na . However, despite their different behavior during the ionization process, ESI(+)-HRMS/MS analyses of 1-4 gave similar fragmentation patterns at m/z 277, 259, 241, and 231 that can be used as diagnostic ions for both skeletons. Moreover, the differentiation strategy based on the nature of the complex SL-adducts and their MS/MS fragmentation pattern were successfully applied for the chemical characterization of the extract from Vernonanthura tweedieana using UPLC-ESI-HRMS/MS. Among the characterized metabolites, SL with hirsutinolide and glaucolide skeletons showed the aforementioned diagnostic fragments and an ionization behavior that was similar to those observed during the water-sample combined injection.
倍半萜内酯 (SL) 具有多种生物学效应。在描述的 SL 骨架中，hirsutinolide 和 glaucolide 尚未通过质谱 (MS) 进行广泛研究，特别是如何在有机基质中区分它们。因此，本文报道了 (1) 基于它们在离子化过程中 MS 行为的分化策略，以及 (2) 两种 SL 亚型的断裂模式建议。通过直接和 UPLC 水样组合注入记录了四个分离的 SL（hirsutinolides 1 和 3；glaucolides 2 和 4）的 ESI(+)-HRMS 数据。这些分析表明，hirsutinolides 和 glaucolides 在直接 MS 注入操作过程中形成 [M+Na] 离子，而在 UPLC 水和样品 MS 注入操作过程中分别观察到 hirsutinolides 和 glaucolides 的 ([M+Na] 和 [M+H-H2O]) 和 [M+H] 离子。计算模拟表明，与复杂的 glaucolide (2)-Na 相比，形成复杂的 hirsutinolide (1)-Na 的制备能较低。然而，尽管它们在离子化过程中表现出不同的行为，但 1-4 的 ESI(+)-HRMS/MS 分析在 m/z 277、259、241 和 231 处给出了相似的裂解模式，可作为两种骨架的诊断离子。此外，基于复杂 SL-加合物的性质及其 MS/MS 裂解模式的分化策略成功应用于使用 UPLC-ESI-HRMS/MS 对 Vernonia tweedieana 提取物的化学表征。在所表征的代谢物中，具有 hirsutinolide 和 glaucolide 骨架的 SL 显示出上述诊断片段和与在水样组合注入过程中观察到的相似的电离行为。
