Investigation of fragmentation behaviours of isoquinoline alkaloids by mass spectrometry combined with computational chemistry.,Scientific Reports

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Investigation of fragmentation behaviours of isoquinoline alkaloids by mass spectrometry combined with computational chemistry.
Scientific Reports ( IF 3.8 ) Pub Date : 2020-01-20 , DOI: 10.1038/s41598-019-57406-7
Zhixing Qing _{1,

2} , Yuqin Xu ₃ , Liuyi Yu ₄ , Jinghong Liu ₁ , Xiuqiong Huang ₁ , Zhaoshan Tang ₅ , Pi Cheng ₁ , Jianguo Zeng _{1,

5}

Affiliation

Isoquinoline alkaloids, which are one of the most important types of alkaloids, are extensively distributed in herbal medicines. However, systematic and comprehensive investigations of the fragmentation behaviours of isoquinoline alkaloids have rarely been reported. Therefore, the goal of the present study is to simultaneously investigate the collision-induced dissociation patterns and the corresponding mechanism of isoquinoline alkaloids by mass spectrometry (MS) combined with computations. Nineteen types of isoquinoline alkaloids (66 compounds) were used as references to identify the characteristic fragmentation behaviours by quadrupole time-of-flight mass spectrometry (Q-TOF/MS) in positive electrospray ionization (ESI) mode. These types of isoquinoline alkaloids were divided into three categories primarily by the characteristic [M-NHR1R2]+ (R1 and R2 represent the substituent groups of the N-atom) fragment ions. High- and low-abundance [M-NHR1R2]+ ions were observed respectively for type I (1-13) and type II (14-29) alkaloids, respectively; however, the characteristic fragments were not detected for type III alkaloids (30-66) because of the existence of a p-π conjugated system. Each type of alkaloid was further classified by its characteristic fragmentation patterns and fragment ions. In addition, isoquinoline alkaloid with vicinal methoxy and hydroxy, vicinal methoxy, methylenedioxy, methoxy, and quaternary N-methyl groups could form the characteristic fragments by the loss of CH3OH, CH4, CH2O or CO, CH3 and CO, and CH3 moieties, respectively. The mechanisms of some interesting fragmentation behaviours, such as the formation of [M-NH3]+ and [M-CH3]+ fragment ions, were further demonstrated by computational chemistry. These characteristic fragmentation behaviours and fragment ions of isoquinoline alkaloids provide a solid foundation for the rapid and high-efficiency structural elucidation of similar metabolites in plant-derived medicines.

中文翻译：

质谱结合计算化学研究异喹啉生物碱的裂解行为。

异喹啉生物碱是最重要的生物碱之一，广泛分布于草药中。但是，很少有关于异喹啉生物碱的碎片化行为的系统和全面的研究。因此，本研究的目的是通过质谱（MS）与计算相结合，同时研究碰撞诱导的解离模式和异喹啉生物碱的相应机理。十九种类型的异喹啉生物碱（66种化合物）被用作参考，以正电喷雾电离（ESI）模式通过四极杆飞行时间质谱（Q-TOF / MS）鉴定特征性碎片行为。这些类型的异喹啉生物碱主要通过特征[M-NHR1R2] +（R1和R2代表N原子的取代基）片段离子分为三类。I型（1-13）和II型（14-29）生物碱分别观察到高和低丰度的[M-NHR1R2] +离子；但是，由于存在p-π共轭体系，未检测到III型生物碱（30-66）的特征片段。每种类型的生物碱通过其特征性的碎片模式和碎片离子进一步分类。此外，具有邻位甲氧基和羟基，邻位甲氧基，亚甲二氧基，甲氧基和季氮甲基的异喹啉生物碱可通过丢失CH3OH，CH4，CH2O或CO，CH3和CO和CH3部分而分别形成特征性片段。。计算化学进一步证明了一些有趣的碎片行为的机制，例如[M-NH3] +和[M-CH3] +碎片离子的形成。异喹啉生物碱的这些特征性断裂行为和碎片离子为植物衍生药物中相似代谢物的快速高效结构解析提供了坚实的基础。

更新日期：2020-01-21

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