Study on the Fragmentation Pathways of Triterpene Glycosides from Apostichopus japonicus Selenka by Negative Electrospray Ionization Mass Spectrometry

The fragmentation pathways of four triterpene glycosides from Apostichopus japonicus Selenka were investigated in negative ion mode by ESI-Q-TOF MS. The M-H^-ions were observed by ESI-MS, from which the molecular weights were obtained. The collision induced dissociation (CID) data of the M-H^-ions provide fragmentation pathways of the triterpene glycosides. Results show that four compounds have the same fragmentation pathway. The cleavage is initiated by a loss of 18 (20)-lactone residue from the aglycon, then consecutively loses monosaccharide residue of sugar chain, and finally yields a signature ion peak at m/z 423. These characteristic fragmentations will be helpful in identifying the structures of triterpene glycosides.