Novel complexes of Co(III) and Ni(II) containing peptide ligands: synthesis, DNA binding and photonuclease activity

Synthesize and multi-spectroscopic studies of zinc-naproxen nanodrug as DNA intercalator agent

The zinc-naproxen complex as a nano-drug (NanoD) was synthesized successfully via fast and effective ultrasound-assisted processes. The chemicophysical properties of the NanoD were determined using FT-IR, XRD, SEM, and EDX mapping analyses. The results confirmed the formation of the 55 nm NanoD laminates. The interaction of the obtained NanoD with calf thymus deoxyribonucleic acid (CT-DNA) was studied as well. Structural and topography changes of DNA in interaction with the NanoD were investigated by atomic force microscopy (AFM). The results of electronic absorption spectroscopy, the DNA-viscosity studies, and competition fluorescence spectroscopy showed that CT-DNA binds to the NanoD through the intercalative binding mode. The data of AFM analysis indicated swollen CT-DNA upon interaction with the NanoD. The in vitro investigation of cytotoxicity of the NanoD on HT-29 and Hep G2 cancer cells demonstrated high cytotoxicity activity of the NanoD than that of cisplatin in HT-29 cell line, especially at lower concentrations.

Evaluation of cobalt(III) complexes as potential hypoxia-responsive carriers of esculetin

Differentiation between hypoxic and normoxic tissues have been exploited for the development of selective chemotherapeutic agents. In this context, cobalt(III)-based coordination compounds have been designed and investigated as prospective hypoxia-responsive drug delivery systems. Three cobalt(III) complexes, namely [Co^III(esc)(py₂en)]ClO₄·(CH₃OH)₂ (1) [Co^III(esc)(TPA)]ClO₄·3H₂O (2) and [Co^III(bipy)₂(esc)]ClO₄·2.5H₂O (3) (py₂en = N,N'-bis(pyridin-2-ylmethyl)ethylenediamine, TPA = tris(2-pyridylmethyl)amine, bipy = 2,2'-bipyridine and esc = 6,7-dihydroxycoumarin or esculetin), were prepared and investigated as potential carriers of esculetin. The spectroscopic and electrochemical properties of 1-3 were investigated and compared. Reactions of the complexes with biologically relevant reducing agents, viz. ascorbic acid, cysteine and glutathione, were monitored spectroscopically for 24 h, in pH 6.2 and 7.4 PBS phosphate buffer saline (PBS) solutions at 37 °C, under air, argon and dioxygen atmospheres. Dissociation of esculetin was observed upon Co³⁺/Co²⁺ reduction preferably under hypoxic conditions, with more effective conversion rates for 3 > 2 > 1. These results illustrate the importance to modulate the Co³⁺/Co²⁺ redox potential through the donor-acceptor properties of the ancillary ligands. Complex 3 is cytotoxic against HCT-116 but not against HT-29 and HEK-293 cells. In addition, DNA-binding studies indicate that interactions of 1 and 3 with the biomolecule are electrostatic.

Synthesis, DNA and BSA binding, in vitro anti-proliferative and in vivo anti-angiogenic properties of some cobalt(iii) Schiff base complexes

In the recent times metal complexes with dual mechanisms of action, anti-cancer and anti-angiogenic, have gained substantial interest in the field of medicinal chemistry.

DNA binding, prominent photonuclease activity and antibacterial PDT of cobalt(II) complexes of phenanthroline based photosensitizers

The chemistry of Co(II) complexes showing efficient light induced DNA cleavage activity, binding propensity to calf thymus DNA and antibacterial PDT is summarized in this article. Complexes of formulation [Co(mqt)(B)₂]ClO₄ 1-3 where mqt is 4-methylquinoline-2-thiol and B is N,N-donor heterocyclic base, viz. 1,10-phenanthroline (phen 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq 2) and dipyrido[3,2-a:2',3'-c]phenazine (dppz 3) have been prepared and characterized. The DNA-binding behaviors of these three complexes were explored by absorption spectra, viscosity measurements and thermal denaturation studies. The DNA binding constants for complexes 1, 2 and 3 were determined to be 1.6 × 10³ M^-1, 1.1 × 10⁴ M^-1 and 6.4 × 10⁴ M^-1 respectively. The experimental results suggest that these complexes interact with DNA through groove binding mode. The complexes show significant photocleavage of supercoiled (SC) DNA proceeds via a type-II process forming singlet oxygen as the reactive species. Antimicrobial photodynamic therapy was studied using photodynamic antimicrobial chemotherapy (PACT) assay against E. coli and all complexes exhibited significant reduction in bacterial growth on photoirradiation.

Ultrasonic effect on RuO2 nanostructures prepared by direct calcination of two new Ru(II)-organic supramolecular polymers

Two novel Ru(II) complexes [(η⁶-p-cymene)RuCl(L1)]PF₆ (R1) and [(η⁶-C₆H₆)RuCl(L1)]PF₆ (R3) with ligand (E)-4-(methylthio)-N-((quinolin-2-yl)methylene)benzenamine (L1), were synthesized and investigated using elemental analysis, IR, ¹H NMR, ¹³C NMR spectroscopy and X-ray crystallography. Complexes R1 and R3 have coordination environments with formulated (η⁶-p-cymene)Ru(N₂Cl) and (η⁶-C₆H₆)Ru(N₂Cl) respectively. The thermal stabilities of compounds R1 and R3 were studied by thermal gravimetric (TG) and differential scanning calorimetry (DSC). The binding of the complexes R1 and R3 to calf thymus DNA (CT DNA) was investigated by using electronic absorption spectra, fluorescence and redox behavior studies. Such experimental data showed that there are interactions between complexes and CT-DNA and the nature of this binding is electrostatic interaction type. Calcination of ultrasonic treated R1 and R3 results in the formation of nanoparticles of RuO₂. The nanoparticles were characterized by IR spectroscopy and X-ray diffraction (XRD). Also size and morphology of nanoparticles were investigated by scanning electron microscopy (SEM).

Synthesis, DNA interactions and antibacterial PDT of Cu(II) complexes of phenanthroline based photosensitizers via singlet oxygen generation

Cu(II) complexes [Cu(mqt)(B)H2O]ClO4(1-3) of 2-thiol 4-methylquinoline and phenanthroline bases (B), viz 1,10-phenanthroline (phen in 1), Dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 2) and Dipyrido[3,2-a:2',3'-c]phenazine (dppz in 3) have been prepared and characterized by elemental analysis, IR, UV-Vis, magnetic moment values, EPR spectra and conductivity measurements. The spectral data reveal that all the complexes exhibit square-pyramidal geometry. The DNA-binding behaviors of the three complexes were investigated by absorption spectra, viscosity measurements and thermal denaturation studies. The DNA binding constants for complexes (1), (2) and (3) were determined to 2.2×10(3), 1.3×10(4) and 8.6×10(4)M(-1) respectively. The experimental results suggest that these complexes interact with DNA through groove-binding mode. The photo induced cleavage studies shows that the complexes possess photonuclease property against pUC19 DNA under UV-Visible irradiation via a mechanistic pathway involving formation of singlet oxygen as the reactive species. Antimicrobial photodynamic therapy was studied using photodynamic antimicrobial chemotherapy (PACT) assay against Escherichiacoli and all complexes exhibited significant reduction in bacterial growth on photoirradiation.

DNA binding, photo-induced DNA cleavage and cytotoxicity studies of lomefloxacin and its transition metal complexes

This work was focused on a study of the DNA binding and cleavage properties of lomefloxacin (LMF) and its ternary transition metal complexes with glycine. The nature of the binding interactions between compounds and calf thymus DNA (CT-DNA) was studied by electronic absorption spectra, fluorescence spectra and thermal denaturation experiments. The obtained results revealed that LMF and its complexes could interact with CT-DNA via partial/moderate intercalative mode. Furthermore, the DNA cleavage activities of the compounds were investigated by gel electrophoresis. Mechanistic studies of DNA cleavage suggest that singlet oxygen ((1)O2) is likely to be the cleaving agent via an oxidative pathway, except for Cu(II) complex which proceeds via both oxidative and hydrolytic pathways. Antimicrobial and antitumor activities of the compounds were also studied against some kinds of bacteria, fungi and human cell lines.

Synthesis and characterization of Co(ii) and Fe(ii) peptide conjugates as hydrolytic cleaving agents and their preferential enantiomeric disposition for CT-DNA: structural investigation of l-enantiomers by DFT and molecular docking studies

Molecular docked model of Co(ii) peptide conjugate with DNA and the mechanism of hydrolytic cleavage of pBR322 DNA.