Identification of C-21 steroidal glycosides from the roots of Cynanchum chekiangense by high-performance liquid chromatography/tandem mass spectrometry.

High-performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC/ESI-MS/MS) was used to identify C-21 steroidal glycosides with immunological activities in roots of Cynanchum chekiangense. In the MS/MS spectra, fragmentation reactions of the [M+Na]+ were recorded to provide structural information about the glycosyl and aglycone moieties. To further confirm the fragments structures, off-line Fourier transform ion cyclotron resonance tandem mass spectrometry (FT-ICR-MS/MS) was also performed. In the study, four known steroidal glycosides cynascyroside C, chekiangensosides A and B, glaucoside H, and four novel steroidal glycosides chekiangensosides C, D, E and chekiangensoside A isomer were identified based on mass spectral data, NMR spectral data and standards. This is the first report on identifying steroidal glycosides in roots of C. chekiangense by HPLC/ESI-MS/MS directly, which could save time and material consuming efforts in traditional phytochemistry analysis.