10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-ones as highly active antimicrotubule agents: synthesis, antiproliferative activity, and inhibition of tubulin polymerization

A series of 10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-ones were synthesized and evaluated for interactions with tubulin and for antiproliferative activity against a panel of human and rodent tumor cell lines. The 4-methoxy analogue 17b was most potent, displaying IC(50) values ranging from 40 to 80 nM, including multidrug resistant phenotypes, and had excellent activity as an inhibitor of tubulin polymerization (IC(50) = 0.52 microM). Concentration-dependent flow cytometric studies showed that KB/HeLa cells treated with 17b were arrested in the G2/M phases of the cell cycle (EC(50) = 90 nM). In competition experiments, 17b strongly displaced [(3)H]-colchicine from its binding site in the tubulin. The results obtained demonstrate that the antiproliferative activity is related to the inhibition of tubulin polymerization.