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Fragmentation study of clerodane diterpenes from Casearia species by tandem mass spectrometry (quadrupole time‐of‐flight and ion trap)
Author(s) -
Danuello Amanda,
Castro Rogério Cardoso,
Pilon Alan Cesar,
Bueno Paula Carolina Pires,
Pivatto Marcos,
Vieira Júnior Gerardo Magela,
Carvalho Flávio Alexandre,
Oda Fernando Bombarda,
Perez Consuelo Javiera,
Lopes Norberto Peporine,
Dos Santos André Gonzaga,
Ifa Demian Rocha,
Cavalheiro Alberto José
Publication year - 2020
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.8781
Subject(s) - chemistry , tandem mass spectrometry , fragmentation (computing) , mass spectrometry , collision induced dissociation , quadrupole ion trap , electrospray ionization , ion trap , tandem , stereochemistry , chromatography , materials science , computer science , composite material , operating system
Rationale Clerodane‐type diterpenes from Casearia species show important pharmacological activites such as antitumor, antimicrobial and anti‐inflamatory. There are several mass spectrometry (MS)‐based methods for identification of diterpenes; however, there is still a lack of MS procedures capable of providing characteristic fragmentation pathways for a rapid and unambiguous elucidation of casearin‐like compounds. Methods Casearin‐like compounds were investigated by electrospray ionization tandem mass spectrometry (ESI‐MS/MS). The fragmentation studies were carried out by tandem mass spectrometry in space (quadrupole time‐of‐flight (QTOF)) using different collision energies and also by tandem mass spectrometry in time (QIT) by selective isolation of product ions. Results Casearin‐like compounds presented a predominance of sodium‐ and potassium‐cationized precursor ions. Both QIT and QTOF techniques provided sequential neutral losses of esters related to the R 1 to R 5 substituents linked to the nucleus of the clerodane diterpenes. The fragmentation pathway is initiated with a cleavage of the ester moieties R 2 followed by the elimination of the ester groups R 3 , both losing neutral carboxylic acids. Using QIT, it was also possible to observe the cleavage of the ester groups R 1 or R 5 by MS 4 experiments. Conclusions Through a rational analysis of the fragmentation mechanisms of Casearia diterpenes it was possible to suggest an annotation strategy based on the sequential cleavages of the ester groups related to the R 2 , R 3 and R 5 substituents. These results will assist studies of the dereplication and metabolomics involving casearin‐like compounds present in complex extracts of Casearia species.