Identification and structural characterization of steroidal glycosides in Hoodia gordonii by ion-trap tandem mass spectrometry and liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry

Abstract

Electrospray ion-trap tandem mass spectrometry (ESI-MS/MS) and high-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOFMS) were used to identify and characterize eight C-21 steroidal glycosides in Hoodia gordonii. A generalized fragmentation pathway was proposed by comparing the spectra acquired for eight C-21 steroidal glycosides. The steroidal glycosides in Hoodia gordonii have been classified into two major core groups: hoodigenin A and calogenin. Using the ESI-TOF method, the major core peak ions generated by hoodigenin A glycosides are m/z 313 and 295 and by calogenin glycosides are m/z 479, 461, 299 and 281, respectively. In the MS/MS spectra, fragmentation reactions of the [M+Na](+) ion were recorded to provide structural information about the glycosyl and aglycone moieties. The data illustrates the ability of positive mode ESI for the identification of hoodigenin A and calogenin glycosides, including the nature of the hoodigenin A and calogenin core, the number of sugar residues and the type of saccharide moiety.