Heteroleptic Schiff base complexes containing terpyridine as chemical nucleases and their biological potential: A study of DNA binding and cleaving, antimicrobial and cytotoxic tendencies

Amidst the very many metallodrugs for the treatment of cancer regularly reported, the development of the next generation of compounds with an aim of overcoming the shortcomings by enhancing biological activity and cytotoxicity but exhibiting low toxicity is essential. Herein we report such octahedral metal(II) complexes (1–12) containing triazole-derived Schiff base as the scaffold. The complexes were synthesized and characterized by means of elemental analysis and various spectroscopic techniques. The complexes were subjected to various investigations that involved their interaction with calf thymus DNA and supercoiled pBR322 DNA. In vitro antimicrobial studies were also conducted in addition to the use of spectrophotometric, spectrofluorometric, cyclic voltammetric and hydrodynamic techniques. Although all complexes showed activity, complex 9 revealed excellent DNA proclivity, DNA cleaving tendencies and antimicrobial efficacy. All copper(II) complexes were evaluated for their antiproliferative activity against a panel of human cancer cell lines (HeLa, Hep-2, MCF-7 and NHDF). Complexes 1–12 showed activity against all the cell lines with low toxicity towards normal cell line, and the activity of complex 9 towards Hep-2 was prominent. The effect of the ligand system on the complexes is also discussed along with the importance of tuning the ligand system.