Planta Med 2012; 78 - PI385
DOI: 10.1055/s-0032-1321072

Structural characterization of steroidal saponins from Dioscorea species using UHPLC-QTOF-MS

B Avula 1, YH Wang 1, M Wang 1, Z Ali 1, TJ Smillie 1, J Zweigenbaum 2, IA Khan 1, 3
  • 1National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences
  • 2Agilent Technologies, Wilmington, DE 19808
  • 3Department of Pharmacognosy, School of Pharmacy, The University of Mississippi, MS 38677, USA

Yam (Dioscorea spp.) is an important tuber plant for edible and medicinal use to promote health and longevity in chinese tradition. In this work, the structural characteristics of the steroidal saponins from the dried rhizomes of Dioscorea species have been identified using UHPLC/TOF-MS in both negative and positive ion modes. The fragmentation patterns of reference standards were investigated and the steroidal saponins in the extracts were identified or tentatively characterized according to the retention times, and MS data. It also provides an excellent approach for rapid screening of steroidal saponins from plant extracts. Protodioscin was used as an example to discuss the fragmentation patterns in detail. In (-)-ESI-MS, gave [M-H]- ions at m/z 1047.53 and in (+)-ESI-MS, the mass spectrum gave [M-H2O+H]+ ions at m/z 1031.54 and showed major fragment ions at m/z 885.48, 739.44, 577.37, 415.32. The fragment ion at m/z 415.3 [aglycone+H]+ was corresponding to the loss of two hexoses and two deoxyhexose. Twenty saponins were identified or tentatively characterized from the crude extracts of Dioscorea species.