Synthesis of naphthalimide-phenanthro [9,10-d]imidazole derivatives: In vitro evaluation, binding interaction with DNA and topoisomerase inhibition

The synthesis and characterization of a series of naphthalimide and phenanthro[9,10-d]imidazole conjugate is described. These compounds are evaluated in vitro for their cytotoxicity towards 60 human cancer cell lines. Derivative 16 shows excellent cytotoxic activity against these cancer cell lines with the range of growth inhibition from - 55.78 to 94.53. The most potent derivative (ethylpiperazine, 16) is further studied to evaluate the interaction with ct-DNA using absorption and emission spectroscopy as well as DNA viscosity measurement. The DNA binding studies indicate that compound 16 is significantly interacted with DNA through groove binding having binding constant value of 7.81 x 10(4) M-1 alongwith partial intercalation between the base pairs of DNA strands. Further, topoisomerase inhibition study suggests that compound 16 is induced apoptosis and inhibits human topoisomerase (Topo-IIa) as a possible intracellular target. Molecular docking study of compound 16 with ct-DNA shows good docking score.