A new blue luminescent dichlorido-bridged dinuclear copper(II) complex with DNA binding and cytotoxic activities: Synthesis, structure and DFT studies

Copper(ii) complexes with tridentate halogen-substituted Schiff base ligands: synthesis, crystal structures and investigating the effect of halogenation, leaving groups and ligand flexibility on antiproliferative activities

To investigate the effect of different halogen substituents and leaving groups and the flexibility of ligands on the anticancer activity of copper complexes, sixteen copper(ii) complexes with eight different tridentate Schiff-base ligands containing pyridine and 3,5-halogen-substituted phenol moieties were synthesized and characterized by spectroscopic methods. Four of these complexes were also characterized by X-ray crystallography. The cytotoxicity of the complexes was determined in three different tumor cell lines (i.e. the A2780 ovarian, HCT116 colorectal and MCF7 breast cancer cell line) and in a normal primary fibroblast cell line. Complexes were demonstrated to induce a higher loss of cell viability in the ovarian carcinoma cell line (A2780) with respect to the other two tumor cell lines, and therefore the biological mechanisms underlying this loss of viability were further investigated. Complexes with ligand L₁ (containing a 2-pycolylamine-type motif) were more cytotoxic than complexes with L₂ (containing a 2-(2-pyridyl)ethylamine-type motif). The loss of cell viability in A2780 tumor cells was observed in the order Cu(Cl₂-L₁)NO₃ > Cu(Cl₂-L₁)Cl > Cu(Br₂-L₁)Cl > Cu(BrCl-L₁)Cl. All complexes were able to induce reactive oxygen species (ROS) that could be related to the loss of cell viability. Complexes Cu(BrCl-L₁)Cl and Cu(Cl₂-L₁)NO₃ were able to promote A2780 cell apoptosis and autophagy and for complex Cu(BrCl-L₁)Cl the increase in apoptosis was due to the intrinsic pathway. Cu(Cl₂-L₁)Cl and Cu(Br₂-L₁)Cl complexes lead to cellular detachment allowing to correlate with the results of loss of cell viability. Despite the ability of the Cu(BrCl-L₁)Cl complex to induce programmed cell death in A2780 cells, its therapeutic window turned out to be low making the Cu(Cl₂-L₁)NO₃ complex the most promising candidate for additional biological applications.

Synthesis, crystal structure and biological activities of a Ag(I) complex based on the V-shaped ligand 1,3-bis(1-benzylbenzimidazol-2-yl)-2-thiapropane

A new silver(I) complex with 1,3-bis(1-benzylbenzimidazol-2-yl)-2-thiapropane (bbbt) and crotonate ligands, with composition [Ag(bbbt)(crotonate)]·CH3CH2OH, has been synthesized and characterized by physicochemical and spectroscopic methods. Single-crystal X-ray diffraction revealed that the coordination environment of the silver(I) center can be described as a distorted tetrahedral geometry, the Ag(I) atom being coordinated by two oxygen atoms from a crotonate anion and two nitrogen atoms from a bbbt ligand. Experimental studies of the DNA-binding properties indicated that the free ligand and the silver(I) complex bind to DNA by intercalation, and the order of the binding affinity is silver(I) complex>free bbbt ligand. The Ag(I) complex exhibits scavenger properties for hydroxyl radicals in in vitro studies.

Mono-, bi- and multi-nuclear silver complexes constructed from bis(benzimidazole)-2-oxapropane ligands and methacrylate: syntheses, crystal structures, DNA-binding properties and antioxidant activities

Three mono-, bi- and multi-nuclear Ag(i) complexes have been synthesized and characterized systematically. The complexes bind to DNA in a intercalate mode. Complex2has the potential ability to scavenge hydroxyl radicals inin vitrostudies.

Interaction studies between biosynthesized silver nanoparticle with calf thymus DNA and cytotoxicity of silver nanoparticles

The interaction of calf thymus DNA (CTDNA) with silver nanoparticles (SNP) has been investigated following spectroscopic studies, analysis of melting temperature (Tm) curves and hydrodynamic measurement. In spectrophotometric titration and thermal denaturation studies of CTDNA it was found that SNP can form a complex with double-helical DNA and the increasing value of Tm also supported the same. The association constant of SNP with DNA from UV-Vis study was found to be 4.1×10(3) L/mol. The fluorescence emission spectra of intercalated ethidium bromide (EB) with increasing concentration of SNP represented a significant reduction of EB intensity and quenching of EB fluorescence. The results of circular dichroism (CD) suggested that SNP can change the conformation of DNA. From spectroscopic, hydrodynamic, and DNA melting studies, SNP has been found to be a DNA groove binder possessing partial intercalating property. Cell cytotoxicity of SNP was compared with that of normal silver salt solution on HeLa cells. Our results show that SNP has less cytotoxicity compared to its normal salt solution and good cell staining property.

Radiosensitivity and Induction of Apoptosis by High LET Carbon Ion Beam and Low LET Gamma Radiation: A Comparative Study

Cancer treatment with high LET heavy ion beam, especially, carbon ion beam ((12)C), is becoming very popular over conventional radiotherapy like low LET gamma or X-ray. Combination of Poly(ADP-ribose) polymerase (PARP) inhibitor with xenotoxic drugs or conventional radiation (gamma or X-ray) is the newer approach for cancer therapy. The aim of our study was to compare the radiosensitivity and induction of apoptosis by high LET (12)C and low LET gamma radiation in HeLa and PARP-1 knocked down cells. We did comet assay to detect DNA breaks, clonogenic survival assay, and cell cycle analysis to measure recovery after DNA damage. We measured apoptotic parameters like nuclear fragmentation and caspase-3 activation. DNA damage, cell killing, and induction of apoptosis were significantly higher for (12)C than gamma radiation in HeLa. Cell killing and apoptosis were further elevated upon knocking down of PARP-1. Both (12)C and gamma induced G2/M arrest although the (12)C had greater effect. Unlike the gamma, (12)C irradiation affects DNA replication as detected by S-phase delay in cell cycle analysis. So, we conclude that high LET (12)C has greater potential over low LET gamma radiation in killing cells and radiosensitization upon PARP-1 inhibition was several folds greater for (12)C than gamma.