New steroid saponins from the seeds of Allium tuberosum L.

Eight new steroidal saponins, including four spirostanol, three furostanol and one cholesterol saponin, have been isolated from the seeds of Allium tuberosum. On the basis of acid hydrolysis and comprehensive spectroscopic analyses, their structures were established as tuberoside N, (25S)-5β-spirostan-2β, 3β-diol 3-O-β-d-glucopyranosyl-(1→2)-[α-l-rhamnopyranosyl (1→4)]-β-d-glucopyranoside; tuberoside O, (25S)-5β-spirostan-2β, 3β, 5-triol 3-O-β-d-glucopyranoside; tuberoside P, (25S)-5β-spirostan-2β, 3β, 5-triol 3-O-α-l-rhamnopyranosyl (1→4)-β-d-glucopyranoside; tuberoside Q, (24S, 25S)-5β-spirostan-2β, 3β, 5, 24-tetraol 3-O-α-l-rhamnopyranosyl (1→4)-β-d-glucopyranoside; tuberoside R, 26-O-β-d-glucopyranosyl-(25S)-5β-furost-20(22)-ene-2β, 3β, 5, 26-tetraol 3-O-β-d-glucopyranoside; tuberoside S, 26-O-β-d-glucopyranosyl-(25S)-5β-furost-20(22)-ene-3β, 26-diol 3-O-β-d-glucopyranosyl-(1→2)-[α-l-rhamnopyranosyl (1→4)]-β-d-glucopyranoside; tuberoside T, 26-O-β-d-glucopyranosyl-(25S)-5α-furost-20(22)-ene-3β, 26-diol 3-O-α-l-rhamnopyranosyl (1→2)-[α-l-rhamnopyranosyl (1→4)]-β-d-glucopyranoside and tuberoside U, 16-O-β-d-glucopyranosyl-(22S, 25S)-cholest-5-ene-3β, 16β, 22, 26-tetraol 3-O-α-l-rhamnopyranosyl (1→2)-[α-l-rhamnopyranosyl (1→4)]-β-d-glucopyranoside, respectively.