Copper, nickel and zinc complexes of 3-acetyl coumarin thiosemicarbazone: Synthesis, characterization and in vitro evaluation of cytotoxicity and DNA/protein binding properties

A new 3-acetylcoumarin thiosemicarbazone (AcTsc) and its copper(II) (1), nickel(II) (2) and zinc(II) (3) complexes were synthesized and characterized by elemental analysis, UV–Vis, FT-IR, ¹H and ¹³C NMR/EPR and mass spectroscopic techniques. The molecular structure of AcTsc, and the complexes 1 and 3 was confirmed by single crystal X-ray crystallography. The interaction of the complexes (1–3) with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) was explored using absorption and emission spectral methods, and viscosity measurement. The spectroscopic results clearly suggested that the complexes (1–3) interacted with CT-DNA through intercalative binding mode. In addition, all the complexes were subjected to cytotoxic studies against human liver carcinoma (HepG-2), lung carcinoma (A549), human leukemic monocyte lymphoma (U937) and lymphoblastoid multiple myeloma cells (IM-9). Complex 3 showed significant cytotoxicity against human liver carcinoma (HepG-2) and lymphoblastoid multiple myeloma (IM-9) cell lines with the IC₅₀ value of 25 μg/mL.