Two novel furostanol saponins from the rhizomes of Dioscorea panthaica Prain et Burkill and their cytotoxic activity

Dioscoresides A and B were isolated from the rhizomes of Dioscorea panthaica and shown to possess a novel furostanol skeleton. Their structures were fully elucidated as 3-O-[β-d-glucopyranosyl-(1→3)-O-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl]-26-O-β-20, 22-seco-d-glucopyranosyl-25 (R)-furosta-5-en-20, 22-dione-3β, 26-diol and 3-O-[bis-α-l-rhamnopyranosyl-(1→4 and 1→2)-β-d-glucopyranosyl]-26-O-β-d-glucopyranosyl-20, 22-seco-25 (R)-furosta-5-en-20, 22-dione-3β, 23(S), 26-triol by spectroscopic techniques and chemical means. These compounds exhibited cytotoxic activity tested in vitro on A375-S2, L929 and Hela cell lines.