Synthesis and antitumor activity of 20-O-linked nitrogen-based camptothecin ester derivatives

A series of nitrogen-based 20S-hydroxyl camptothecin ester derivatives were prepared. 3-Aminopropionate of camptothecin was found more cytotoxic in vitro on several human tumor cell lines than 3-amidopropionate of camptothecin. Ester 16 showed best antitumor activity in vivo and in vitro in all esters we prepared.