Four new steroidal saponins from the seeds of Allium tuberosum

Four new steroidal saponins, 26-O-β-D-glucopyranosyl-(25S,20R)-20-O-methyl-5α-furost- 22(23)en-2α,3β,20,26-tetraol 3-O-α-L-rhamnopyranosyl-(1→2)- [α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside (1); 26-O-β-D-glucopyranosyl-(25S,20R)-5α-furost-22(23)-en- 2α,3β,20,26-tetraol 3-O-α-L-rhamnopyranosyl-(1→2)-[α-L- rhamnopyranosyl-(1→4)]-β-D-glucopyranoside (2); 26-O-β-D-glucopyranosyl-(25S,20S)-5α-furost-22(23)-en- 2α,3β,20,26-tetraol 3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl- (1→4)]-β-D-glucopyranoside (3); and 26-O-β-D-glucopyranosyl-(25S,20S)-5α-furost-22(23)-en- 3β,20,26-triol 3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl- (1→4)]-β-β-glucopyranoside (4), have been isolated from the seeds of Allium tuberosum. Their structures were established by spectroscopic studies such as MS, IR, NMR, and 2D-NMR and the results of acid hydrolysis and named tuberosides F, G, H, and I, respectively.