Stereochemical differentiation of C‐7 hydroxyltaxane isomers by electrospray ionization mass spectrometry |
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| Authors: | Guang‐Bo Ge Rong Zhang Chun‐Zhi Ai Yu‐Qi He Yan‐Yan Zhang Xing‐Bao Liu Li Yang Zheng‐Tao Wang Ling Yang |
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| Institution: | 1. Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China;2. Graduate University of the Chinese Academy of Sciences, Beijing, China;3. State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, China;4. Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, China |
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| Abstract: | In this study, different electrospray ionization mass spectrometric (ESI‐MS) methods were utilized to analyze several pairs of taxane stereoisomers including paclitaxel and 7‐epi‐paclitaxel. Both ESI‐MS and tandem mass spectrometry (MS/MS) techniques provided stereochemically dependent mass spectra in negative‐ion mode, and all studied stereoisomers could be easily distinguished based on their characteristic ions or distinct fragmentation patterns. MS/MS experiments for several taxane analogues at various collision energies were performed to elucidate potential dissociation pathways. The gas‐phase deprotonation potentials were also calculated to estimate the most thermodynamically favorable deprotonation site using DFT B3LYP/6‐31G(d). The results of the theoretical studies agreed well with the fragmentation patterns of paclitaxel and 7‐epi‐paclitaxel observed from MS/MS experiments. In addition, it was found that liquid chromatography (LC)/ESI‐MS was a useful and sensitive technique for assignment of C‐7 taxane stereoisomers from realistic samples. Copyright © 2009 John Wiley & Sons, Ltd. |
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