Synthesis, characterization, DNA binding and cleavage, BSA interaction and anticancer activity of dinuclear zinc complexes

Three new zinc(II) complexes: [Zn-2(L-1)(2)Cl-2](ClO4)(2)center dot C2H5OH (1) and [(Zn2LX4)-X-2]center dot 2CH(3)CN (X = Br for 2, Cl for 3), utilizing two new and interrelated di-nucleating polypyridyl ligands (L-1, L-2), have been synthesized and characterized by using various physico-chemical techniques. The interactions of three complexes with CT-DNA have been explored by using absorption, emission and CD spectral methods, which reveal that three complexes bind to CT-DNA by partial intercalation binding modes. Notably, in the presence of H2O2 as a revulsant or an activator, the cleavage abilities of all complexes are obviously enhanced. The hydrolytic mechanism was demonstrated by adding standard radical scavengers and anaerobic reaction. Further, the protein binding ability has been monitored by quenching of tryptophan emission in the presence of complexes using BSA as a model protein. The quenching mechanisms of BSA by the complexes are static procedures. In addition, the in vitro cytotoxicity of the complexes on three human tumor cells lines (HeLa, MCF-7 and RL952) and the apoptosis-inducing activity of 3 were assessed by MTT, Clonogenic assay, Hoechst 33342 staining, Cell cycle and Annexin V binding experiments.