DNA/BSA interaction, bio-activity, molecular docking simulation study and electrochemical properties of hydrazone Schiff base derived Cu(II)/Ni(II) metal complexes: Influence of the nuclearity and metal ions

Abstract

Three new transition metal complexes of a tridentate Schiff base ligand, H2L = N-(2-hydroxybenzylideneamino) benzamide, were synthesized in the presence of pyridine, 3-methylpyridine and the corresponding metal salts, and were characterized by FT-IR, UV–Vis and Raman spectroscopies, and cyclic voltammetry (CV). The crystal structures of the three complexes, [CuII2(L)2(py)2]·2ClO4(1), CuII2(L)2(3-Mepy)2(ClO4)2 (2) and [NiII(L)(py)3]ClO4 (3), were determined through X-ray crystallography. In the Cu complexes two different kinds of contacts were be found: shorter (in typical ranges) and longer (Cu–O around 2.5 Å), which assemble the complexes into dimers. The coordination geometry is (taking into account the longer contacts) square-pyramidal in 1, while complexes 2 and 3 show an octahedral geometry. Numerous biological studies have been conducted on H2L and complexes 1–3. In vitro, their antibacterial activities were examined against Gram-positive and Gram-negative bacteria. The results of these studies indicated that all compounds had antibacterial activity against Gram-positive bacteria. Furthermore, binding studies of H2L and its complexes with calf thymus DNA (CT-DNA) were studied. Results analyzing the binding of H2L and the complexes to CT-DNA revealed a hyperchromic effect and a non-intercalative mode of binding. These observations also indicate significant alterations of the bovine serum albumin (BSA) secondary structure in circular dichroism (CD) spectra, specifically in the presence of H2L and the complexes, with the reduction of the α-helices content. A molecular docking simulation study of the complexes with Mycobacterium tuberculosis enoyl-acyl carrier protein reductase, InhA, using the Hex (v8.0.0) docking software indicated their probable inhibition property.