Isolation of a new saponin and cytotoxic effect of saponins from the root of Platycodon grandiflorum on human tumor cell lines.

A novel triterpenoid saponin, deapioplatycoside E (1) was isolated from the root extract of Platycodon grandiflorum, together with the seven known saponins 2 - 8, i.e., platycoside E (2), deapioplatycodin D 3 (3), platycodin D 3 (4), polygalacin D 2 (5), platycodin D 2 (6), deapioplatycodin D (7) and platycodin D (8). The structure of the new saponin 1 was determined on the basis of spectral analysis and chemical evidence. The crude saponin fraction (ED 5 0 : ca. 10 - 15μg/mL) and compounds 6 - 8 (ED 5 0 : ca. 4 - 18μg/mL) exhibited significant inhibition on the proliferation of five kinds of cultured human tumor cell lines, i.e., A549 (non-small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nerve system) and HCT-15 (colon), in vitro.