SAPONINS FROM AERIAL PARTS OF ALFALFA (MEDICAGO-SATIVA)

The structures of three saponins from the leaves of alfalfa, cultivar Resis, were established as 28-O-[beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]medicagenate, 28-O-[beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]-3-O-beta-D-glucopyranosyl-medicagenate, and 28-O-[beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]-3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]medicagenate; in the North American cultivar Lahontan, two saponins were isolated and their structures determined as 28-O-[beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]-3-O-beta-D-glucuronopyranosylmedicagenate and 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]soyasapogenol B. Structural elucidations were performed on peracetylated derivatives of the saponins by using H-1 and C-13 NMR with techniques such as COSY, relayed COSY, HOHAHA, ROESY, HMBC, and HMQC.