Fragmentation patterns study of iridoid glycosides in Fructus Gardeniae by HPLC-Q/TOF-MS/MS

Iridoid glycosides (IGs), the major constituents in Fructus Gardeniae, have demonstrated various pharmacological activities, but there is no systematic chemical profile of IGs in Fructus Gardeniae in the published literature until now. Therefore, it is imperative that a rapid and sensitive high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (HPLC-Q/TOF-MS/MS) method is established for comprehensive characterization of IGs in Fructus Gardeniae. Firstly, the fragmentation patterns of six known IGs were investigated and proposed and further concluded the diagnostic fragment ions and characteristic fragmentation pathways. Then, based on the summarized fragmentation patterns and the known compounds in the literatures, the other IGs in Fructus Gardeniae were identified successively. As a result, a total of 20 IGs were identified, of which three pairs of epimers were structurally characterized and differentiated. More importantly, one compound, the isoshanzhiside methyl ester, was tentatively identified as a new compound. The results of this study demonstrate the superiority of HPLC-MS with a high-resolution mass spectrometer for the rapid and sensitive structural elucidation of the multiple groups of constituents in Fructus Gardeniae.