Structure and cytotoxicity of zinc (II) and cobalt (II) complexes based on 1,3,5-tris(1-imidazolyl) benzene

Three novel complexes, [Zn (tib)(2)center dot(H2O)(2)]center dot(NO3)(2) (1), [Co (tib)(2)]center dot 2NO(3) (2) and [Co-2(tib)(2)(btc)]center dot H2O (3) [H(4)btc = 1,2,4,5-benzenetetracarboxylic acid; H(2)tib = 1,3,5-tris(1-imidazolyl)benzene], were synthesized and characterized by single-crystal X-ray, IR and elemental analysis. The interaction of these complexes with FS-DNA (fish sperm DNA) was monitored, and binding constants were determined using UV/Vis, which revealed that they have the ability to bind to FS-DNA. DNA-binding constants (K) for the three complexes were 2.2 x 10(4) m(-1), 0.7 x 10(4) m(-1) and 0.09 x 10(4) m(-1), respectively. The interaction capacity of the complexes with FS-DNA has been investigated by fluorescence spectroscopy. Stern-Volmer quenching plot values for complexes 1, 2 and 3 were 0.3784, 0.1028 and 0.076, respectively. The viscosity measurement suggested that complexes 1, 2 and 3 interact with DNA in an intercalation mode. In addition, anti-cancer activities of these complexes investigated through MTT assays in vitro indicated that the complexes showed good cytotoxic activity against cancer cell lines. Cytotoxic activity of test complexes against two different cancer cell lines (HeLa and KB cells) showed significant cancer cell inhibition rates. Flow cytometry experiments and morphological apoptosis studies showed that the complexes induced apoptosis of HeLa tumor cell lines. Finally, a further molecular docking technique was employed to confirm the binding of the complexes toward the molecular target DNA.