Structural characterization of trace stilbene glycosides in Lysidice brevicalyx Wei using liquid chromatography/diode-array detection/electrospray ionization tandem mass spectrometry

The mass fragmentation patterns of stilbene glycosides isolated from the genus Lysidice were investigated by negative ion electrospray ionization tandem mass spectrometry, and the influence of collision energy on their fragmentation behavior is discussed. It is found that the presence of the Y0− and B0− ions in the MS2 spectra is characteristic for 1 → 6 linked diglycosyl stilbenes, while the Y0−, Y1−, and Z1− ions are representative ions of 1 → 2 linked diglycosyl stilbenes. These results indicate that ESI-MSn in the negative ion mode can be used to differentiate 1 → 6 and 1 → 2 linked diglycosyl stilbenes. Based on the fragmentation rules, 9 new trace constituents were identified or tentatively characterized in a fraction of Lysidice brevicalyx by using HPLC/HRMS and HPLC-DAD/ESI-MSn. The results of the present study can assist in on-line structural identification of analogous constituents and targeted isolation of novel compounds from crude plant extracts.