A new ionizable chromophore of 1,4-bis(alkylamino)benzo[g]phthalazine which interacts with DNA by intercalation

The tricyclic heteroaromatic nucleus of 1,4-bis(alkylamino)benzo[g]phthalazine can be protonated at physiological pH, depending on the nature of the side chains. The interaction of the 3-methoxypropyl derivative with calf thymus and closed, circular DNA has been studied with UV-vis spectroscopy and NMR. The effect of drug binding on the topology of closed, circular DNA was determined by topoisomerase-I catalyzed relaxation of the complex followed by gel electrophoresis. The results strongly support intercalative binding and suggest that this series of compounds are promising targets for anticancer activity evaluation.