Two New Cytotoxic Spirostane‐Steroidal Saponins from the Roots of Bletilla striata

Two new spirostane‐steroidal saponins, bletilnoside A (1) and bletilnoside B (2), together with five known compounds, 3–7, were isolated from the roots of Bletilla striata (Thunb.) Reichb. F. The structures of the new compounds were determined based on their 1D‐ and 2D‐NMR spectral data. The isolated compounds 1–7 were tested for cytotoxicity against four human tumor cells (A549, SK‐OV‐3, SK‐MEL‐2, and HCT15) in vitro using a sulforhodamin B bioassay, and compounds 1, 2, and 5 showed significant cytotoxicities against all tested tumor cell lines with IC50 values ranging from 3.98±0.16 to 12.10±0.40 μM.