Ruthenium(II) complexes: Cellular uptake, cytotoxicity, DNA-binding, photocleavage and antioxidant activity studies

Two new ruthenium(II) complexes [Ru(dmp)2(DNPIP)]2+ 1 and [Ru(dmp)2(DAPIP)]2+ 2 were synthesized and characterized. The DNA-binding behaviors of these complexes were investigated by absorption spectra, viscosity measurements and photocleavage. The DNA-binding constants for complexes 1 and 2 have been determined to be 6.24 (±0.11) × 104 and 1.64 (±0.49) × 104 M−1. The results suggest that complexes 1 and 2 intercalate between the DNA base pairs. Binding stoichiometries were studied through a luminescence-based Job plot. The major inflection points for complexes 1 and 2 at χ = 0.31 and χ = 0.51 were observed. The data were consistent with 2:1 and 1:1 bp [complex]/[DNA] binding mode. Complex 1 shows higher activity than complex 2 against the selected tumor cell lines. In addition, the cellular uptake and antioxidant activity on hydroxyl radical were also explored.