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Low‐energy collision‐induced dissociation tandem mass spectrometry of 7‐acetonyloxycoumarins
Author(s) -
Timonen Juri,
Romppanen Ritva,
Aulaskari Paula,
Jänis Janne
Publication year - 2013
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.6735
Subject(s) - chemistry , tandem mass spectrometry , fragmentation (computing) , fourier transform ion cyclotron resonance , mass spectrometry , collision induced dissociation , dissociation (chemistry) , homolysis , electrospray ionization , ion , electron ionization , analytical chemistry (journal) , radical ion , ketene , ionization , radical , medicinal chemistry , chromatography , organic chemistry , computer science , operating system
RATIONALE Coumarins are naturally occurring, oxygen‐containing heterocycles with considerable pharmaceutical potential. For structural elucidation of natural or synthetic coumarins, tandem mass spectrometry (MS n ) represents an essential tool. In this study, fragmentation characteristics of twenty‐two 7‐acetonyloxycoumarins, having promising anti‐inflammatory properties, were investigated with low‐energy collision‐induced dissociation (CID). METHODS Accurate mass measurements were performed on a 12‐T Fourier transform ion cyclotron resonance (FT‐ICR) instrument. Most CID‐MS n measurements were performed on a quadrupole ion trap (QIT) instrument, except some additional CID‐MS 2 measurements performed on the FT‐ICR instrument for further confirmation of some fragment ions. Positive‐ion electrospray ionization (ESI) was employed throughout. Density functional theory (DFT) calculations (B3LYP) were carried out to analyze putative ion structures/fragmentation channels. RESULTS The most favourable dissociation channel for [M + H] + ions of 7‐acetonyloxycoumarins was the elimination of a C 3 H 5 O ● radical (57 Da) from the 7‐acetonyloxy group via homolytic bond cleavage. The resulting phenolic radical ion was the primary fragment ion for the most compounds studied. Losses of even‐electron neutrals, C 3 H 4 O and C 3 H 6 O (56 and 58 Da), were also observed. These primary eliminations were accompanied with other characteristic neutral losses from the coumarin skeleton, including H 2 O, CO, CO 2 , and C 2 H 2 O (ketene). In addition, propene (C 3 H 6 ) loss was also observed for 4‐propyl or 3‐ethyl‐4‐methyl‐substituted compounds. CONCLUSIONS The studied coumarins showed interesting characteristics in low‐energy CID due to the presence of a 7‐acetonyloxy group, leading to both even‐ and odd‐electron product ions. The main dissociation channels observed for each compound were highly dependent on the substituents in the benzopyranone ring. The present results will advance our knowledge on the dissociation characteristics of both synthetic and natural coumarins. Copyright © 2013 John Wiley & Sons, Ltd.