Synthesis of ruthenium(II) complexes and characterization of their cytotoxicity in vitro, apoptosis, DNA-binding and antioxidant activity

A new ligand DBHIP and its two ruthenium (II) complexes [Ru(bpy)2(DBHIP)](ClO4)2 (1) and [Ru(phen)2(DBHIP)](ClO4)2 (2) have been synthesized and characterized. The binding behaviors of the two complexes to calf thymus DNA were investigated by absorption spectra, viscosity measurements, thermal denaturation and photoactivated cleavage. The DNA-binding constants for complexes 1 and 2 have been determined to be 8.87 ± 0.27 × 104 M−1 (s = 1.83) and 1.32 ± 0.31 × 105 M−1 (s = 1.84). The results suggest that these complexes interact with DNA through intercalative mode. The cytotoxicity of DBHIP, complexes 1 and 2 has been evaluated by MTT assay. The apoptosis assay was carried out with acridine orange/ethidium bromide (AO/EB) staining methods. The studies on the mechanism of photocleavage demonstrate that superoxide anion radical (O2−) and singlet oxygen (1O2) may play an important role.

Graphical abstractThe DNA-binding properties of complexes [Ru(bpy)2(DBHIP)]2+ and [Ru(phen)2(DBHIP)]2+ were investigated. The cytotoxicity was evaluated by MTT assay. The apoptosis assay was performed with acridine orange/ethidium bromide (AO/EB) staining methods.Figure optionsDownload full-size imageDownload as PowerPoint slide