Tandem mass spectrometric fragmentation behavior of lignans, flavonoids and triterpenoids in Streblus asper

RATIONALE: An unambiguous identification of compounds can be achieved by comparison of known fragmentation patterns. While the literature about fragmentation mechanisms of lignans, flavonoids and triterpenoids is few. So the present study analyses the fragmentation mechanisms of these compounds isolated from Streblus asper. METHODSElectrospray ionization ion trap mass spectrometry (ESI-ITMS) and atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-ITMS) were used to obtain the MSn spectra of the compounds. By analyzing the differences between the ions, the fragmentation mechanisms of these compounds were explored. RESULTSOf the 29 compounds detected, 17, 7, and 5 were lignans, flavonoids and triterpenoids, respectively. The majority of lignans were found to give [M - H](-) ions of sufficient abundance for MSn analyses. The flavonoids were prone to the loss of CO and H2O. The triterpenoids always lost one formic acid molecule and two hydrogens, or one H2O from [M - H](-) to form the most abundant product ion in the MSn spectrum. CONCLUSIONSESI/APCI-ITMS were demonstrated to be fast, effective and practical tools to characterize the structures of flavonoids, triterpenoids and lignans. Results of the present study can help identify the analogous constituents by analyzing their MSn spectra. Copyright (c) 2014 John Wiley & Sons, Ltd.