Structures of toxic steroidal saponins from Narthecium asiaticum MAXIM.

The full structures of the two steroidal saponins from Narthecium asiaticum MAXIM. We previously identified as toxic substances by monitoring the toxicity in guinea pigs were phytochemically reinvestigation on the aerial parts of the plant. The desired toxic saponins (6,7) were isolated together with two known lignan glucosides (1,2), a known flavonoid glucoside (3), a new furanone glucoside (4), a known steroidal saponin (5) and a new steroidal saponin (8). The structures of the new furanone glucoside, toxic saponins and new saponin were determined on the basis of spectroscopic data and acid- or enzymatic-catalyzed hydrolysis to be (S)-5-beta-D-glucopyranosyloxy-4-methoxyfuran-2(5H)-one (4), (25R,S)-5 beta-spirostan-3 beta-ol 3-O-[O-beta-D-glucopyranosyl-(1-->2)-] O-[alpha-L-arabinopyranosyl-(1-->3)]-beta-D-galactopyranoside] (6), (25R,S)-5 beta-spirostan-3 beta-ol 3-}O[O-beta-D-glucopyranosyl-(1-->2- O-[beta-D-xylopyranosyl-(1-->3)]-beta-D-galactopyranoside] (7) and (24S,25R)-5 beta-spirostan-3 beta,24-diol 3-O-[O-beta-D- glucopyranosyl-(1-->2)-O-]alpha-L-arabinopyranosyl-(1-->3)]-beta-D - galactopyranoside] (8), respectively.