DNA binding, cleavage, docking, biological and kinetic studies of Cr(III), Fe(III), Co(II) and Cu(II) complexes with ortho‐vanillin Schiff base derivative

Abstract

Abstract2‐((4‐Hydroxyphenylimino)methyl)‐6‐methoxyphenol ligand was synthesized by refluxing 2‐hydroxy‐3‐methoxybenzaldehyde with p‐aminophenol in 1:1 molar ratio. A series of transition metal complexes with the synthesized ligand OVAP, [Cr(OVAP)2] (1), [Fe(OVAP)2] (2), [Co(OVAP)2] (3) and [Cu(OVAP)2] (4) is reported. Characterisation of the complexes by sophisticated analytical techniques revealed the geometry around central metal ion to be octahedral for 1, 2 and 3 complexes and complex 4 with square planar geometry. Kinetic parameters of the complexes were estimated by Coats–Redfern method, and the complexes were found to be thermally stable. DNA binding affinity of these metal complexes was explored by means of fluorescence, ultraviolet (UV)–visible and viscosity studies and the studies suggested intercalative mode. The Kb values from the absorption studies are 2.98 × 105, 2.16 × 105, 4.66 × 105 and 5.46 × 105 M−1 and Ksv values from fluorescence studies are 3.79 × 104, 2.14 × 104, 4.92 × 104 and 6.47 × 104 M−1 for 1, 2, 3 and 4 complexes, respectively. Nuclease studies in the presence of H2O2 were performed using pUC19 supercoiled DNA. Docking studies were done using human DNA topoisomerase‐I (DNA topoI) receptor protein. Biological studies revealed higher activity for complexes than the ligand, and in vitro antitumour studies showed that complexes 3 and 4 possess potential inhibitory efficiency with an IC50 of 42.32 ± 0.5 and 38.12 ± 1.2 μg/ml correspondingly.