Pyrazole-bridged late first row transition metal complexes derived from hexadentate compartmental ligand: synthesis, characterization, antibacterial activity, and DNA binding/cleavage studies

Mitochondria-localizing dicarbohydrazide Ln complexes and their mechanism of in vitro anticancer activity

Dicarbohydrazide Ln complexes trigger SK-OV-3/DDP cell apoptosis via a mitochondrial dysfunction pathway.

Bis-(2-Hydroxybenzylidene)-1H-Pyrazole 3,5-Dicarbohydrazide as a Novel Chemosensor for the Detection of Endogenous Zinc: A Fluorometric Study

The study reports synthesis and photophysical studies of a new zinc sensing pyrazole scaffold structurally characterized to be bis(2-hydroxybenzylidene)-1H-pyrazole-3,5-dicarbohydrazide (PHSA). Excitation of the probe at 330 nm results in an emission band at 417 nm which ratiometrically red shifts to 466 nm upon Zn²⁺ addition in an unprecedented way. The photo induced electron transfer (PET) coupled intramolecular charge transfer (ICT) working for a dual-channel fluorescence emission pathway is observed and studies were supported with density functional theory and NMR titration experiments. The probe exhibited dissociation constant of 1.2156 and detection limit as low as 992 nM. The cytotoxic effects of the probe on 60 tumour cell lines were tested. The intracellular zinc sensing with reversible binding potential is verified with fluorescence microscopy experiment.

Synthesis and characterization of new unsymmetrical Schiff base Zn (II) and Co (II) complexes and study of their interactions with bovin serum albumin and DNA by spectroscopic techniques

Two novel tetra-coordinated Cobalt(II) and Zinc (II) chelate series with the general formula of [Co (L)·2H₂O] (1) and [Zn (L)] (2) [L=N-2-hydroxyacetophenon-N'-2-hydroxynaphthaldehyde-1,2 phenylenediimine)] with biologically active Schiff base ligands were synthesized and recognized by elemental analysis and multi-nuclear spectroscopy (IR and ¹H and ¹³C NMR); then, their biological activities including DNA and protein interactions were studied. The interaction of the synthesized compounds with bovine serum albumin (BSA) was investigated via fluorescence spectroscopy, showing the affinity of the complexes for these proteins with relatively high binding constant values and the changed secondary BSA structure in the presence of the complexes. The interaction of these compounds with CT-DNA was considered by UV-Vis technique, emission titration, viscosity measurements, helix melting methods, and circular dichroism (CD) spectroscopy, confirming that the complexes were bound to CT-DNA by the intercalation binding mode. Furthermore, the complexes had the capability to displace the DNA-bound MB, as shown by the competitive studies of these complexes with methylene blue (MB), thereby suggesting the intercalation mode for the competition. Finally, the theoretical studies carried out by the docking method were performed to calculate the binding constants and recognize the binding site of the BSA and DNA by the complexes. In addition, in vitro and in silico studies showed that the compounds were degradable by bacterial and fungal biodegradation activities.

Antibacterial, DNA interaction and cytotoxic activities of pendant-armed polyamine macrocyclic dinuclear nickel(II) and copper(II) complexes

A series of dinuclear nickel(II) and copper(II) complexes (1-6) of hexaaza macrocycles of 2,6-diformyl-4-methylphenol with three different benzoyl pendant-arms, 2,2'-benzoyliminodi(ethylamine) trihydrochloride (L), 2,2'-4-nitrobenzoyliminodi(ethylamine) trihydrochloride (L') and 2,2'-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride (L″) have been synthesized and characterized by spectral methods. The electrochemical studies of these complexes depict two irreversible one electron reduction processes around E(1)pc=-0.62 to -0.76 V and E(2)pc=-1.21 to -1.31, and nickel(II) complexes (1-3) exhibit two irreversible one electron oxidation processes around E(1)pa=1.08 to 1.14 V and E(2)pa=1.71 to 1.74 V. The room temperature magnetic moment values (μeff, 1.52-1.54 BM) indicate the presence of an antiferromagnetic interaction in the binuclear copper(II) complexes (4-6) which is also observed from the broad ESR spectra with a g value of 2.14-2.15. The synthesized complexes (1-6) were screened for their antibacterial activity. The results of DNA interaction studies indicate that the dinuclear complexes can bind to calf thymus DNA by intercalative mode and display efficient cleavage of plasmid DNA. Further, the cytotoxic activity of complexes 2, 5 and 6 on human liver adenocarcinoma (HepG2) cell line has been examined. Nuclear-chromatin cleavage has also been observed with PI staining and comet assays.