| Abstract
| - By applying a novel cell- and caspase-based HTS assay, 2-amino-3-cyano-7-(dimethylamino)-4-(3-methoxy-4,5-methylenedioxyphenyl)-4H-chromene (1a) has been identified as a potentapoptosis inducer. Compound 1a was found to induce nuclear fragmentation and PARP cleavage,as well as to arrest cells at the G2/M stage and to induce apoptosis as determined by the flowcytometry analysis assay in multiple human cell lines (e.g. Jurkat, T47D). Through structure−activity relationship (SAR) studies of the 4-aryl group, a 4- and 7-fold increase in potency wasobtained from the screening hit 1a to the lead compounds 2-amino-4-(3-bromo-4,5-dimethoxyphenyl)-3-cyano-7-(dimethylamino)-4H-chromene (1c) and 2-amino-3-cyano-7-(dimethylamino)-4-(5-methyl-3-pyridyl)-4H-chromene (4e), with an EC50 of 19 and 11 nM in the caspase activationassay in T47D breast cancer cells, respectively. The 2-amino-4-aryl-3-cyano-7-(dimethylamino)-4H-chromenes also were found to be highly active in the growth inhibition MTT assay, withGI50 values in the low nanomolar range for compound 1c. Significantly, compound 1c was foundto have a GI50 value of 2 nM in the paclitaxel resistant, p-glycoprotein overexpressed, MES-SA/DX5 tumor cells. Functionally, compound 1c was found to be a potent inhibitor of tubulinpolymerization and to effectively inhibit the binding of colchicine to tubulin. These resultsconfirm that the cell-based caspase activation assay is a powerful tool for the discovery of potentapoptosis inducers and suggest that the 4-aryl-4H-chromenes have the potential to be developedinto future anticancer agents.
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