Oxovanadium(iv/v) lawsone-based complexes: synthesis, characterization, DFT studies, and multifunctional biological activities

Abstract

Three oxovanadium(IV/V) complexes with lawsone (HLw) were synthesized, including [VO(Lw)₂(H₂O)]·H₂O (1), [VO(Lw)₂Cl]·H₂O (2), and [VO₂(Lw)(bpy)] (3). They were characterized by CHN elemental analysis, FTIR, ¹H NMR, UV-Vis, ESI-MS, magnetic susceptibility, molar conductivity, and thermogravimetric analysis (TGA), and DFT calculations. Spectroscopic results indicated that the ligand acts as a monoanionic bidentate (O, O) donor ligand. In view of the potential of vanadium-based anticancer agents, the interactions of the complexes with biomacromolecules (ctDNA, tRNA, and BSA) were investigated. The complexes exhibited moderate binding affinity toward ctDNA and tRNA (10⁴ M⁻¹ range), with a preference for tRNA, and binding modes consistent with partial intercalative and/or surface interactions. Protein binding studies suggested a static quenching mechanism with BSA. The in vitro cytotoxic activity was evaluated against HeLa (cervical), HepG-2 (hepatocellular), and MCF7 (breast) human cell lines. Complex (2) displayed the highest activity and selectivity (selectivity index = 4.89 against HeLa) compared to Cisplatin, while showing lower toxicity toward WI-38 (lung) cells. The complexes also exhibited antioxidant activity (SOD-like IC₅₀ = 10.27 ± 0.54 µM), consistent with their redox properties, which may contribute to their observed cytotoxic effects. DFT calculations and molecular docking studies supported experimental findings, revealing favorable electronic properties and stable interactions with biological targets. In addition, preliminary antibacterial and α-amylase inhibitory assays were performed to explore broader bioactivity. Overall, these findings suggest that oxovanadium–lawsone complexes possess promising biological activity and merit further investigation.