New Steroidal Saponins from the Rhizomes of Paris vietnamensis and Their Cytotoxicity

Four new spirostanol saponins, named pavitnosides A-D (1-4), with six known steroidal saponins 5-10 were isolated from the rhizomes of Paris vietnamensis. Their chemical structures were determined based on extensive spectroscopic studies and chemical methods. The aglycones of pavitnoside B and pavitnoside C were not reported in previous work. The cytotoxicity of all saponins was evaluated against human glioblastoma U87MG and U251 cell lines. The new spirostanol saponin 1 displayed weak anti-proliferative activity against U87MG cell line and the known saponins 8 and 9 exhibited significant cytotoxicity against the two tumor cell lines, with IC50 values of 2.16 to 3.14 mu M, but did not affect the growth of primary cultures of human astrocytes.