Synthesis of cholestane saponins as mimics of OSW-1 and their cytotoxic activities

To fulfill the structure-activity relationship (SAR) of OSW-1, and aim at finding the simplest structural part while maintaining most of the biological activities, six cholestane saponins were synthesized by introducing OSW-1 disaccharide (2-O-4-methoxybenzoyl-β-D-xylopyranosyl-(1→3)-2-O-acetyl-α-L-arabinopyranosyl) and its 1→4-linked analogue to the 7-hydroxy or 16-hydroxy of steroidal sapogenins. Cytotoxic activities of the products were tested. Compounds 1 and 3 exhibited potent cytotoxicities against five types of human tumor cells, with minimum IC(50) of 2.0 and 75 nM, respectively. And due to its high activity and easy accessibility compound 1 could be a potential candidate for new anti-tumor agents.