Steroidal saponins and cytoxicity of the wild edible vegetable—Smilacina atropurpurea

Four new steroidal saponins, smilacinoside A (1), B (2), C (3), and D (4), together with three known saponins, funkioside D (5), aspidistrin (6) and 26-O-β-d-glucopyranosyl-22-methoxyl-(25R)-furost-5-en-3β,26-diol 3-O-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 4)-β-d-galactopyranoside (7) were isolated from the dried tender aerial parts of Smilacina atropurpurea (Franch.) Wang et Tang. The structures of new compounds were elucidated as diosgenin 3-O-α-l-rhamnopyranosyl-(1 → 2)-O-β-d-galactopyranoside (1), diosgenin 3-O-α-l-rhamnopyranosyl-(1 → 3)-[6-O-palmitoxyl]-O-β-d-galactopyranoside (2), 26-O-β-d-glucopyranosyl-(25R)-furost-5-en-3β,22ξ,26-triol 3-O-α-l-rhamnopyranosyl-(1 → 2)}-β-d-galactopyranoside (3) and 26-O-β-d-glucopyranosyl-22-methoxyl-(25R)-furost-5-en-3β,26-diol 3-O-α-l-rhamnopyranosyl-(1 → 2)-β-d-galactopyranoside (4) on the basis of chemical methods and detailed spectroscopic analysis, including 1D and 2D NMR techniques and single-crystal X-ray diffraction, respectively. Six of these compounds and MeOH extract were tested for their in vitro cytotoxicity toward K562 human tumor cells by an improved MTT method. Smilacinoside A, funkioside D and aspidistrin exhibited significant in vitro cytotoxicity against K562 with IC50 values of 1.09, 2.93 and 0.47 μg/mL, respectively.