Characterization and identification of baccharane glycosides in Impatientis Semen by rapid-resolution liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Baccharane glycosides represent a group of rare saponins in plant kingdom and have been regarded as chemical marker for quality control of Impatientis Semen. Based on the structural skeleton, the baccharane glycosides were classified into three types: hosenkol A, hosenkol B and hosenkol C type. In this study, a rapid-resolution liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (RRLC/ESI-Q-TOF MS/MS) was performed to investigate the fragmentation behaviours of baccharane glycosides from Impatientis Semen. In full scan mass spectrum, the accurate determination of molecular formula was obtained by the predominant ion [M+COO]− in negative mode. In the MS/MS spectrum, fragmentation reactions of the [M+H]+ acquired in positive mode were recorded to provide abundant structural information on the aglycone and glycosyl moieties. The characteristic ion for hosenkol A and hosenkol B type glycosides was at m/z 399, while for hosenkol C type glycosides the diagnostic ion was at m/z 381. Neutral losses of monosaccharide, disaccharide, H2O and C3H4 were observed for stepwise structural characterization. As a result, 19 compounds including 9 target saponins and 10 non-target saponins were rapidly screened out in ethanol extract of Impatientis Semen, and 5 of them were found to be novel baccharane glycosides.