Characterisation and identification of triterpene saponins in the roots of red beets (Beta vulgaris L.) using two HPLC–MS systems

Triterpene saponins are important bioactive constituents with an enormous variety in structure widely distributed in many plants. Here, we profiled triterpene saponins from the skin and flesh of red beetroot Beta vulgaris L. cultivars Nochowski from 2012 and 2013 season using reversed-phase liquid chromatography combined with negative-ion electrospray ionisation quadrupole mass spectrometry. We tentatively identified 44 triterpene saponins, of which 37 had not been detected previously in the root of red beets and 27 saponins were tentatively identified as potentially new compounds. All observed compounds were glycosides of four different aglycone structures, of which akebonoic acid and gypsogenin were not detected previous in red beetroot. Based on the high-resolution mass measurements among these 44 detected saponins 10 groups of isomers were identified. We report for the first time that 18 saponins with dioxolane-type (2 saponins) and acetal-type (16 saponins) substituents were detected in the roots of red beet.