DNA binding, photocleavage and topoisomerase inhibitory activity of polypyridyl ruthenium(II) complexes containing the same ancillary ligand and different main ligands

The binding and photocleavage properties of [Ru(phen)2L]2+ {where phen is 1,10-phenanthroline and L is 2-(4-formylphenyl)imidazo[4,5-f][1,10]phenanthroline (fmp) or 2-(2′,3-dibromo-4-formyl-phenyl)imidazo[4,5-f][1,10]-phenanthroline (fmp-2Br)} with regard to DNA were investigated using various biophysical techniques. Results suggest that the two complexes can bind to DNA via an intercalative mode with different affinities and efficiently photocleavage pBR322 DNA in vitro under irradiation. Furthermore, the results of topoisomerase inhibition and DNA strand passage assay reflect that both complexes are efficient dual topoisomerase I and IIα inhibitors.