Quasi-MSn identification of flavanone 7-glycoside isomers in Da Chengqi Tang by high performance liquid chromatography-tandem mass spectrometry

BACKGROUND Da Chengqi Tang (DCT) is a common purgative formula in Chinese medicine. Flavanones are its major active compounds derived from Fructus Aurantii Immaturus. The present study developed an LC-MS/MS method to characterize two pairs of flavanone 7-glycoside isomers, i.e., hesperidin versus neohesperidin and naringin versus isonaringin. METHODS After solid phase purification, components in sample were separated on a Agilent zorbax SB-C18 (5 microm, 250 mm x 4.6 mm) analytical column. ESI-MS and quasi-MSn were performed in negative ion mode to obtain structural data of these two pairs of flavanone 7-glycoside isomers. Moreover, UV absorption was measured. RESULTS There was no intra-pairs difference in the UV-Vis and MS/MS spectra of the two pairs of 7-glycoside isomers, whereas the mass spectrometry fragmentation pathways between pairs were different. CONCLUSION The present study developed a LC-MS/MS method to explore the inter- and intra-pair difference of two pairs of flavanone 7-glycoside isomers.