Characterization of steroidal saponins in crude extracts from Dioscorea zingiberensis C. H. Wright by ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

Steroidal saponins are the major bioactive constituents of Dioscorea zingiberensis C. H. Wright (D. zingiberensis). In this work, ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS/MS) was applied to the separation and characterization of steroidal saponins in crude extracts from D. zingiberensis. The results showed that fragment ions from glycosidic and cross-ring cleavages gave a wealth of structural information related to aglycone skeletons, sugar types and the sequence of sugar units. According to the summarized fragmentation patterns, identification of steroidal saponins from D. zingiberensis could be fulfilled, even when reference standards were unavailable. As a result, a total of thirty-one saponins with five aglycone skeletons, including fourteen new trace saponins, were identified or tentatively elucidated in crude extracts from D. zingiberensis based on their retention times, the mass spectrometric fragmentation patterns, and MS and MS/MS data. Copyright (c) 2010 Elsevier B.V. All rights reserved.