A number of tricyclic carboxamides have been synthesized and tested to evaluate their ability to reverse multidrug resistance in the CHRC/5 cell line. Among them the acridone derivatives were the most potent. A key feature is the presence of a dimethoxybenzyl or phenethylamine cationic site, separated from the tricyclic lipophilic part by a carbamoylphenyl chain. Optimization led to compounds 2 orders of magnitude more ...
