Saponins in alfalfa (Medicago sativa L.) root and their structural elucidation

Twenty-four saponins have been identified in alfalfa roots, including 13 medicagenic acids, 2 zanhic acids, 4 hederagenins, 1 soyasapogenol A, 2 soyasapogenol B's, 1 soyasapogenol E, and 1 bayogenin glycoside. Ten of the identified compounds, including 3-O-[beta-D-glucopyranosyl(1-->3)-beta-D-glucopyranosyl]-28-O-beta-D-glucopyranoside medicagenate, 3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside] medicagenic acid, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-28-beta- D-glucopyranoside medicagenate, 3-O-[beta-D-glucuronopyranosyl methyl eater]-28-O-[beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside] medicagenate, 3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl]-21-O-alpha-L-rhamnopyranoside soyasapogenol A, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl (1-->2)glucopyranosyl] -28-O-[beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside] medicagenate, 3-O-[beta-D-glucopyranosyl( 1-->2)-beta-D-glucopyranosyl(1-->2)glucopyranosyl]-28-O-[beta-D-xylopyranosyl(1-->4)-)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside) medicagenate, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-28-O-[beta-D-xylopyranosyl (1-->4)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside] zanhic acid, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-28-O-{beta-D-xylopyranosyl(1-->4)-[beta-D-apiofuranoside-(1-->3)]-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside}zanhic acid, and 3-O-[beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl]-28-O-beta-D-glucopyranoside bayogenin, were not reported before, and their structures were established by spectral (FAB-MS and NMR) techniques. In addition, 3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranoside] soyasapogenol E was identified in the roots for the first time.