Cobalt(ii) terpyridine complexes: synthesis, characterization, antiproliferative activity and molecular docking with proteins and DNA

Abstract

The combination of CoCl₂·6H₂O and a series of 4′-(substituted-phenyl)-2,2′:6′,2′′-terpyridine compounds bearing hydrogen (L¹), p-methoxyl (L²), p-mesyl (L³), p-methyl (L⁴), p-bromo (L⁵), p-iodo (L⁶), p-phenyl (L⁷), p-chloro (L⁸), and p-fluoro (L⁹) leads to the formation of nine Co-based terpyridine complexes (1–9), which were characterized by elemental analysis and infrared spectroscopy. Their crystals obtained through solution evaporation or a hydrothermal process were investigated by single crystal X-ray diffraction. All complexes are mononuclear with central Co(II) coordinated to two terpyridine ligands to form a sandwich-like structure. The in vitro antiproliferative activity of these complexes against human lung carcinoma cell line (A549), human hepatocellular carcinoma cell line (Bel-7042) and human esophageal cancer cell line (Eca-109) was investigated, and a study on their toxicity was carried out on a normal human liver cell line (HL-7702). All complexes exhibit a better antiproliferative activity on cancer cells than the commercialized chemotherapy drug cisplatin. The UV-Vis spectroscopy results reveal that these complexes interact with CT-DNA in the embedding mode. The circular dichroic (CD) analysis confirms their strong affinity binding with CT-DNA and suggests that all compounds stack onto the base pairs of CT-DNA. Biomolecules including B-DNA, survivin protein, and DNA-topoisomerase I were selected to execute molecular docking, and the binding sites of complexes on these biomacromolecules were determined via computational docking analysis.