Antitumor Agents 155. Synthesis and Biological Evaluation of 3′,6,7-Substituted 2-Phenyl-4-quinolones as Antimicrotubule Agents

A series of 3′,6,7-substituted 2-phenyl-4-quinolones were designed and synthesized as antimitotic antitumor agents. All compounds showed cytotoxic effects (log GI ₅₀ ≤ −4.0; log drug molar concentration required to cause 50% inhibition) against the growth of a variety of human tumor cell lines, including those derived from solid tumors such as non-small cell lung, colon, central nervous system, ovary, prostate, and breast cancers, when evaluated in the National Cancer Institute's 60 human tumor cell line in vitro screen. The most potent compound (26) demonstrated strong cytotoxic effects with GI ₅₀ values in the nanomolar or subnanomolar range in almost all the tumor cell lines. Compound 26 was also a potent inhibitor of tubulin polymerization and radiolabeled colchicine binding to tubulin, with activity comparable to those of the potent antimitotic natural products colchicine, podophyllotoxin, and combretastatin A-4.