Design, Synthesis and Characterization of a Methoxyhydrazide‐Based Copper(II)–Schiff Base Complex: Investigation of Peroxidase‐Mimetic Behaviour, DNA/BSA‐Binding Interactions, Molecular Docking and Cytotoxic Potential Against HeLa Cells

ABSTRACT A mononuclear Cu(II)–Schiff base complex, indicated as MBMBC, has been synthesized from a methoxyhydrazide‐based ligand (HL), ( E )‐ N ′‐(5‐bromo‐2‐hydroxy‐3‐methoxybenzylidene)‐4‐methoxybenzohydrazide. The structure of the complex was determined by single‐crystal X‐ray diffraction analysis, which revealed that the Cu(II) centre is chelated by two oxygen and one imine nitrogen atom of the deprotonated ligand, an aquo and a nitrate ion to form a distorted square pyramidal geometry around the metal. The catalytic activity of the MBMBC complex was assessed for peroxidase‐like oxidation reactions involving o ‐phenylenediamine (OPD), 3,3′‐diaminobenzidine (DAB) and pyrogallol in methanol, using hydrogen peroxide (H 2 O 2 ) as the oxidant. The complex also showed strong binding affinity towards calf thymus DNA (CT‐DNA) and bovine serum albumin (BSA), as confirmed by UV–vis absorption spectroscopy. Significant fluorescence quenching of both the DNA–ethidium bromide (EB) complex and BSA was observed upon addition of the complex MBMBC, suggesting effective binding interactions. To support the experimental findings, molecular docking studies were performed to determine the binding site and interaction energies. Furthermore, the anticancer potential of the MBMBC complex was assessed on the cervical cancer cell line (HeLa) via an in vitro MTT assay, demonstrating its promising cytotoxic activity. Flow cytometry analysis using Annexin V/PI was performed to determine the mode of cell death, which was again reinforced by Hoechst 33342 staining. Generation of reactive oxygen species (ROS) was also envisaged using DCFH‐DA. All these data together suggested that the complex MBMBC is demonstrating a potential anticancer effect.