Fragmentation pathways of synthetic and naturally occurring coumarin derivatives by ion trap and quadrupole time-of-flight mass spectrometry.

Abstract

Synthetic and natural coumarin derivatives possess a wide range of biological activities. Fragmentation pathway studies are important in identifying both naturally occurring coumarins and synthetic coumarins with novel structures and properties. The fragmentation pathways of eleven coumarin derivatives are investigated by electrospray ionization (ESI) ion-trap mass spectrometry (ESI-ITMSn ) and ESI quadrupole time-of-flight mass spectrometry (QTOFMS) in positive mode. Compounds 1-9 in this study were newly synthesized in our laboratory. Compounds 10 and 11 were isolated from the root of Zanthoxylum armatum. The major fragmentation pathways for 11 coumarin derivatives are greatly affected by the heterocyclic ring structures and the side-chain substituents. Typical losses of small neutral molecules, such as CH3 CH2 OH, CH2 =CH2 , CO, and H2 O, are observed for compounds 1-5. Compounds 6-9 share similar fragmentation pathways through losses of CO, aromatic rings, and the coumarin skeleton. The main product ions at m/z 205, 219, and 220 observed for compounds 10 and 11 are produced by the loss of C5 H12 O2 , C4 H10 O2 , and the C4 H9 O2 radical, respectively. The fragmentation pathways of 11 coumarin derivatives are elucidated based on ITMSn and QTOFMS spectral data. Differences in the structures of the heterocyclic rings and side-chain substituents strongly affect the fragmentation pathways of the coumarins. The present results will facilitate further research into the fragmentation pathways and structural characterization of these classes of compounds with diverse structures. Copyright © 2015 John Wiley & Sons, Ltd.