Spectroscopic, SOD, anticancer, antimicrobial, molecular docking and DNA binding properties of bioactive VO(IV), Cu(II), Zn(II), Co(II), Mn(II) and Ni(II) complexes obtained from 3-(2-hydroxy-3-methoxybenzylidene)pentane-2,4-dione

Abstract

Novel macrocyclic Schiff base complexes [[ML]X; where M = Cu(II), Co(II), Ni(II), Zn(II), Mn(II) and VO(IV)^; L = macrocyclic ligand; X = Cl₂ and SO₄²⁻] have been synthesized and characterized by microanalytical, ¹H, ¹³C NMR, IR, Mass, UV–Vis, EPR spectral studies, as well as conductivity data. All the complexes exhibit square-planar geometry except vanadium complex. Magnetic susceptibility measurements and high conductance data reveal the monomeric and electrolytic nature of the complexes. Electronic absorption, cyclic voltammetry, viscosity measurements have been carried out on the interaction of the complexes with DNA. The results suggest that the complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA. Using gel electrophoresis experiment in the presence and absence of oxidant (H₂O₂) the nuclease cleavage activity of the complexes has been performed on plasmid DNA. The results demonstrate that most of the complexes have promising superoxide dismutase (SOD)-mimetic activity. The in vitro cytotoxicity of ligand and its complexes has also been evaluated against human breast and colon carcinoma cells. Binding interactions and energies of ligand and its metal complexes [ML]²⁺ (M = VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II)) against the receptors EGFR and HER2 are performed using the Auto dock module. Consequently, it is found that the ligand is strong inhibitor for EGFR and HER2 while [VOL]SO₄ is good inhibitor for EGFR and [ZnL]Cl₂ is moderate inhibitor for HER2. The antimicrobial activity of the ligand and its complexes against bacteria Salmonella typhi, Staphylococcus aureus, Escherichia coli and Bacillus subtilis and fungi Aspergillus niger, Aspergillus flavus, Candida Albicans and Rhizoctonia bataicola. The complexes have higher activities than the macrocyclic free Schiff base.

Communicated by Ramaswamy H. Sarma

GRAPHICAL ABSTRACT

Interaction of [VOL]SO₄ to the binding sites of target protein EGFR (PDB ID: 4HJ0).

Research Highlights

1. Macrocyclic Schiff base and its metal complexes were synthesized.

2. Complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA.

3. Vanadyl complex is a good inhibitor for EGFR.

4. The complexes of copper, zinc and vanadium show efficient antitumor activity.

5. Copper and vanadium complexes have superior antimicrobial activity than the standards.

Keywords:

• DNA cleavage
• intrinsic binding constant
• SOD
• antimicrobial activities

Acknowledgments

The authors thank the Principal and the Management of the Mepco Schlenk Engineering College, Sivakasi for encouraging this research work and providing the instrumental facility.

Disclosure statement

No potential conflict of interest was reported by the authors.