Steroidal saponins from Calamus insignis, and their cell growth and cell cycle inhibitory activities

Three novel spirostanol-type (2, 3, and 5) and a furostanol-type (4) steroidal saponins were isolated from the stems of Calamus insignis (Palmae), along with a known steroidal saponin (1) by bioassay guided purification. The chemical structures of 1–5 were established on the basis of spectroscopic analysis and the result of acidic hydrolysis. Compounds 1, 2, 3, and 5 showed cell growth inhibitory activity against HeLa cells at a concentration of less than 10 μM, and 1 exhibited a cell cycle inhibitory effect at the G2/M stage at concentrations of 1.5 and 2.9 μM by flow cytometric analysis. This effect seems to be correlated with large expression of p21 and inhibition of dephosphorylation of cdc2 according to the result of Western blotting analysis.

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