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-d-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. Keywords: Steroidal saponins; tuberoside F, G, H, I; Allium tuberosum; Liliaceae