Synthesis and biological evaluation of novel bivalent β-carbolines as potential antitumor agents

A series of bivalent β-carbolines with a spacer between the 3-carboxyl oxygens was synthesized and their cytotoxic activities in vitro and antitumor efficacies in vivo were evaluated. Compound 22 exhibited potent antitumor activity against Lewis lung cancer in mice with a tumor inhibition rate of 64.2%.