Co and Cu complexes with 2-acetylpyridine-4-hydroxy phenylacetyl acylhydrazone: Synthesis, crystal structures, CT-DNA/BSA binding behaviors, antibacterial activities and molecular docking studies

Abstract

Two mononuclear complexes [Co(HL)L]NO3 (1) and [Cu(HL)2](NO3)2 (2)were synthesized from the reaction of 2-acetylpyridine-4-hydroxy phenylacetyl acylhydrazone (HL) with copper/cobalt nitrate hydrate. The single-crystal XRD results revealed the central Co and Cu ions in two complexes are both six-coordinated showing a distorted octahedral geometry. Thermal stabilities of 1, 2 and HL were explored by thermogravimetry (TG) and the apparent activation energy (Ea) followed the order 2 > 1 > HL. The interactions of 1, 2, HL with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were investigated through UV–Vis absorption spectroscopy, fluorescence spectroscopy, microcalorimetry and molecular docking approach. From UV–Vis absorption spectroscopy and fluorescence spectroscopy results, it is shown that 1, 2 and HL can bind with CT-DNA by intercalation mode and quench the fluorescence of BSA through static process. The binding constants Kib of three compounds toward CT-DNA/BSA followed the order: 1 > 2 > HL. Thermogenic curves of three compounds interacting with CT-DNA and BSA were measured by microcalorimetry. The calculated enthalpies, entropies and Gibbs' free energy change (ΔH > 0, ΔS > 0, ΔG < 0) indicated that all the interaction processes were endothermic and spontaneous. Molecular dockingresults further validated the intercalation binding mode of 1, 2 and HL with CT-DNA and the fluorescence quenching of tryptophan in BSA in presence of three compounds. It also demonstrated that hydroxyl, benzene ring, pyridine ring, and carbonyl group of 1, 2, HL are the most favorable binding site in DNA/BSA interaction. The antimicrobial activities of HL, 1 and 2 against Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis) were determined presenting that 1 and HL can inhibit the growth of S. aureus and B. subtilis, separately. Cellular uptakes of 1 and 2 into S. aureus and B. subtilis showed the amount of Co accumulation in S. aureus is bigger than that of Cu.