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Mass spectrometry for characterization of homologous piperidine alkaloids and their activity as acetylcholinesterase inhibitors
Author(s) -
Freitas Thamires R.,
Danuello Amanda,
Viegas Júnior Claudio,
Bolzani Vanderlan S.,
Pivatto Marcos
Publication year - 2018
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.8172
Subject(s) - chemistry , piperidine , mass spectrometry , tandem mass spectrometry , electrospray ionization , fragmentation (computing) , collision induced dissociation , electron ionization , stereochemistry , chromatography , organic chemistry , ionization , ion , computer science , operating system
Rationale Piperidine alkaloids from Senna spectabilis constitute a rare class of natural products with several biological activities. However, the absence of chromophores makes their structural elucidation by conventional methods a great challenge. In this context, mass spectrometry emerges as a powerful tool for metabolomics studies. Methods The piperidine alkaloids (−)‐cassine and (−)‐spectaline and the semisynthetic derivatives (−)‐3‐ O ‐acetylcassine and (−)‐3‐ O ‐acetylspectaline were investigated by electrospray ionization tandem mass spectrometry (ESI‐MS/MS) in the positive mode and electron ionization mass spectrometry (EI‐MS). ESI fragmentation studies were performed with a quadrupole time‐of‐flight instrument; N 2 was used as collision gas. The acetylcholinesterase inhibitory activity of the investigated compounds was evaluated by bioautography and microplate screening assays. Results ESI‐MS/MS and EI‐MS provided valuable and complementary information about the structure of the piperidine compounds. Collision‐induced dissociation experiments (MS/MS) revealed that neutral elimination of water or acetic acid is the major fragmentation pathway, which agrees with the stereochemistry proposed for (−)‐cassine and (−)‐spectaline and the semisynthetic derivatives (−)‐3‐ O ‐acetylcassine and (−)‐3‐ O ‐acetylspectaline. Conclusions The ESI‐MS/MS and EI‐MS studies allowed us to propose fragmentation mechanisms for piperidine alkaloids and derivatives. Therefore, mass spectrometry is an important tool for characterizing the structure of these compounds and for supporting further metabolomics studies.