Analysis of bisdesmosidic saponins in Saponaria vaccaria L. by HPLC-PAD-MS: identification of new quillaic acid and gypsogenin 3-O-trisaccharides.

A high-performance liquid chromatographic method using photodiode array and single quadrupole electrospray mass detection for analysis and profiling of bisdesmosidic saponins in Saponaria vaccaria seed was developed. Profiles of seed extract from three different plant sources were obtained and found to contain the same saponins, albeit in different proportions. Several known saponins were identified by selected ion extraction of quasi-molecular ions from the total ion chromatogram and confirmed by their mass spectra. Application of high cone voltages afforded mass spectra containing key diagnostic fragments and relatively strong singly charged quasi-molecular ions. In addition to previously identified saponins, several new quillaic acid and gypsogenin bisdesmosides could be detected via mass spectral analysis. Five of these were tentatively identified as pentose homologues of known saponins, having an added xylosyl residue linked to the 3-O-glucuronyl group (1 --> 3). The stereochemistry and identity of the xylosyl linkage in the new saponins was determined by chemical means. Previously reported vaccaric or segetalic acid-type bisdesmosides could not be detected in any of the extracts.