DNA oxidative cleavage induced by the novel peptide derivatives of 3-(quinoxalin-6-yl)alanine in combination with Cu(II) or Fe(II) ions

The in vitro assessment of dipyridophenazine complexes in H-ras oncogene transformed rat embryo fibroblast 5RP7 cell line

Purpose The aim of this study is to detect apoptotic and cytotoxic/antiproliferative effects of a ligand substance and its metal derivatives. The substances were investigated by using an h-ras oncogene transformed rat embryo fibroblast cell line (5RP7). Methods The cytotoxic influences of dipyrido[3,2-a:2',3'c]phenazine ligand, dipyrido[3,2-a:2',3'c] phenazine-platinum(II) complex ([Pt(dppz)Cl₂]) and dipyrido[3,2-a:2',3'c] phenazine-gold(III) complex ([Au(dppz)Cl₂]Cl) were determined with MTT (3[4,5-dimetiltiyazol2-yl]-2,5-difeniltetrazolyum bromid) assay on 5RP7 cells. Results Dipyrido[3,2-a:2',3'c] phenazine, dipyrido[3,2-a:2',3'c] phenazine-platinum(II) complex ([Pt(dppz)Cl₂]) and dipyrido[3,2-a:2',3'c] phenazine-gold(III) complexes ([Au(dppz)Cl₂]Cl) caused significant increase in cytotoxicity in a dose and time dependent manner. The effects of dipyridophenazine ligand (dppz) and its metal derivatives on apoptosis were monitorized using cytotoxic dose (10 μM) DAPI fluorescent staining. It was shown that dppz and its compounds induced apoptosis. Conclusions These findings show that dpzz and its complexes can be studied as novel alternative chemotherapeutics in cancer treatment.

Design, synthesis and DNA binding activities of late first row transition metal(II) complexes of bi- functional tri - and tetratopic imines

A series of novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of tri and tetratopic hydrazones have been prepared. Ligands L(1)H(2) and L(2)H(2) were synthesized by the condensation of 2-formylphenoxyacetic acid with 2-hydrazinobenzothiazole and 2-hydroxy-3-hydrazinebenzopyrazine, respectively. The prepared complexes were characterized by the analytical and spectral techniques. All the complexes were found to be monomeric in nature with octahedral geometry. Both ligands were found to be electrochemically active in the working potential range showing single electron transfer process attributed to the deprotonation of carboxylic group of the 2-formylphenoxyacetic acid. The potency of the ligand and its complexes as antimicrobial agents has been investigated and made to interact with Escherichia coli DNA to investigate the binding/cleaving ability by absorption, hydrodynamic and electrophoresis studies.

Mechanism of copper surface toxicity in vancomycin-resistant enterococci following wet or dry surface contact

Contaminated touch surfaces have been implicated in the spread of hospital-acquired infections, and the use of biocidal surfaces could help to reduce this cross-contamination. In a previous study we reported the death of aqueous inocula of pathogenic Enterococcus faecalis or Enterococcus faecium isolates, simulating fomite surface contamination, in 1 h on copper alloys, compared to survival for months on stainless steel. In our current study we observed an even faster kill of over a 6-log reduction of viable enterococci in less than 10 min on copper alloys with a "dry" inoculum equivalent to touch contamination. We investigated the effect of copper(I) and copper(II) chelation and the quenching of reactive oxygen species on cell viability assessed by culture and their effects on genomic DNA, membrane potential, and respiration in situ on metal surfaces. We propose that copper surface toxicity for enterococci involves the direct or indirect action of released copper ionic species and the generation of superoxide, resulting in arrested respiration and DNA breakdown as the first stages of cell death. The generation of hydroxyl radicals by the Fenton reaction does not appear to be the dominant instrument of DNA damage. The bacterial membrane potential is unaffected in the early stages of wet and dry surface contact, suggesting that the membrane is not compromised until after cell death. These results also highlight the importance of correct surface cleaning protocols to perpetuate copper ion release and prevent the chelation of ions by contaminants, which could reduce the efficacy of the surface.