DNA and protein binding, double-strand DNA cleavage and cytotoxicity of mixed ligand copper(II) complexes of the antibacterial drug nalidixic acid

摘要

Abstract The water soluble mixed ligand complexes [Cu(nal)(diimine)(H2O)](ClO4) 1–4, where H(nal) is nalidixic acid and diimine is 2,2′-bipyridine (1), 1,10-phenanthroline (2), 5,6-dimethyl-1,10-phenanthroline (3), and 3,4,7,8-tetramethyl-1,10-phenanthroline (4), have been isolated. The coordination geometry around Cu(II) in 1 and that in the Density Functional Theory optimized structures of 1–4 has been assessed as square pyramidal. The trend in DNA binding constants (K b) determined using absorption spectral titration (K b: 1, 0.79±0.1 2, 1.06±0.1 3, 1.79±0.2 4, 1.84±0.2×105 M?1) is in line with that (K app) determined by competitive ethidium bromide binding studies. The large red-shift (10