Macrocyclic Cu(II) and Pd(II) complexes with new 16-membered tetradentate [N4] ligand: synthesis, characterization, 3D molecular modeling and in vitro anticancer and antimicrobial activities

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

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 SO₄^2-] 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. Interaction of [VOL]SO₄ to the binding sites of target protein EGFR (PDB ID: 4HJ0). Research HighlightsMacrocyclic Schiff base and its metal complexes were synthesized.Complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA.Vanadyl complex is a good inhibitor for EGFR.The complexes of copper, zinc and vanadium show efficient antitumor activity.Copper and vanadium complexes have superior antimicrobial activity than the standards.

Macrocyclic Schiff base complexes as potent antimicrobial agents: Synthesis, characterization and biological studies

A series of Cu^II, Co^II, Zn^II and Ni^II, complexes of 3⁴,7⁴-dimethyl-1²,1⁵,5²,5⁵-tetrahydro-2,4,6,8-tetraaza-1,5(2,5)-difurana-3,7(1,2)-dibenzenacyclooctaphane based ligand have been synthesized by template methodology. Characterization of the synthesized complexes has been carried out with the help of various physicochemical and spectroscopic techniques like Infra-Red, ESI-MS, ESR, UV-visible, CHN (elemental analyses), molar conductance, magnetic moment and NMR. Antimicrobial efficacy of the newly designed macrocyclic complexes has performed by the assistance of agar well diffusion method. In-vitro hemolytic and DNA binding studies were also performed in order to analyze or interpret the mode and binding efficiencies as well as the % hemolysis exhibited by the complexes. DFT/TD-DFT studies were carried out in order to elucidate the better insight into the structural parameters. Energy minimization and quantum chemical parameters were calculated using Gaussian09W program.