Synthesis and antitumor activity of novel indole derivatives containing α-aminophosphonate moieties

A series of novel indole derivatives containing α-aminophosphonate moieties were synthesized as antitumor agents. The in vitro cytotoxic activity of the compounds was evaluated against human hepatoma cells (HepG2) and human gastric cancer cells (MGC-803) by MTT assay, revealing that most of target compounds exhibited moderate to high antitumor activities. Among them, compound C5 (IC50 = 34.2 µM) demonstrated superior inhibitory activities against HepG2 compared with 5-fluorouracil (IC50 = 78.7 µM). It is noteworthy that compound B7 (IC50 = 35.7 µM) displayed higher inhibitory activities against MGC-803 than that of 5-fluorouracil (IC50 = 82.0 µM).