Bidesmosidic and monodesmosidic triterpenoid saponins from the grain of Amaranthus hypochondriacus

Five known bidesmosidic triterpenoid saponins (1-5) and their hydrolysates, namely two new monodesmosidic triterpenoid saponins (1 ' and 2 ') and three known saponins (3 '-5 '), were isolated from Amaranthus hypochon-driacus seeds. The structures of the new compounds were determined using interpreting 1D and 2D nuclear magnetic resonance (NMR) data and high-resolution electrospray ionisation mass spectrometry (HRESI-MS) analyses as 3-O-8-D-glucuronopyranosyl-30-normedicagenic acid (1 ') and 3-O-[alpha-L-rhamnopyranosyl (1 -> 3)-8-D-glucuronopyranosyl] bayogenin (2 '). For the first time, 5 and 5 ' were isolated from Medicago plants as the first examples of glycosides in medicagenic acid from Amaranthus plants. While bidesmosidic saponins showed no cytotoxicity, monodesmosidic saponins, except for 1 ', showed moderate cytotoxicity against human cervix adenocarcinoma (HeLa) cells. In addition, monodesmosidic saponins showed anti-fungal activity against the rice blast fungus (Pyricularia oryzae).