Interaction with CT-DNA and in vitro cytotoxicity of two new copper(II)-based potential drugs derived from octanoic hydrazide ligands

Two copper(II) complexes [Cu(Hpmoh)(NO3)(NCS)] (1) and [Cu(peoh)(N3)]2 (2) were designed and synthesized by reaction of Cu(NO3)2·3H2O with hydrazone Schiff base ligands,abbreviated with Hpmoh and Hpeoh. Hpmoh and Hpeoh were prepared by condensation reaction of octanoic hydrazide with pyridine-2-carboxyaldehyde and 2-acetylpyridine, respectively. Complexes 1 and 2 were characterized using different analytical techniques such as FT-IR, UV-Vis, IR, EPR and single X-ray diffraction (XRD) analyses as well as computational methods (DFT). The XRD of 1 and 2 shows a mononuclear or a dinuclear structure with the copper(II) centre adopting a slightly distorted square pyramidal geometry. In water-containing solution and in DMSO, 1 and 2 undergo a partial transformation with formation of [Cu(Hpmoh)(NO3)(NCS)] (1) and [Cu(Hpmoh)(NO3)(H2O/DMSO)] (1a) in one system and [Cu(peoh)(N3)] (2a) in the other one, as supported by DFT calculations. Docking simulations confirmed that the intercalation is the preferred binding mode with DNA for 1, 1a and 2a, but suggested that the minor groove binding is also possible. A significant fluorescence quenching of the DNA-ethidium bromide conjugate was observed upon the addition of complexes 1 and 2 with a quenching constant around 104 M-1 s-1. Finally, both 1 and 2 were examined for anti-cancer activity using MDA-MB-231 (human breast adenocarcinoma) and A375 (malignant melanoma) cell lines through in vitro MTT assay which suggest comparable cancer cell killing efficacy, with the higher effectiveness of 2 due to the dissociation into two [Cu(peoh)(N3)] units.

Anti-toxoplasma activity and DNA-binding of copper(II) and zinc(II) coordination compounds with 5-nitroimidazole-based ligands

Tetrahedral copper(II) and zinc(II) coordination compounds from 5-nitroimidazole derivatives, viz. 1-(2-chloroethyl)-2-methyl-5-nitroimidazole (cenz) and ornidazole 1-(3-chloro-2-hydroxypropyl)-2-methyl-5-nitroimidazole (onz), were synthesized and spectroscopically characterized. Their molecular structures were determined by X-ray diffraction studies. The complexes [Cu(onz)2X2], [Zn(onz)2X2], [Cu(cenz)2X2] and [Zn(cenz)2X2] (X- = Cl, Br), are stable in solution and exhibit positive LogD7.4 values that are in the range for molecules capable of crossing the cell membrane via passive difussion. Their biological activity against Toxoplasma gondi was investigated, and IC50 and lethal dose (LD50) values were determined. The ornidazole copper(II) compounds showed very good antiparasitic activity in its tachyzoite morphology. The interaction of the coordination compounds with DNA was examined by circular dichroism, fluorescence (using intercalating ethidium bromide and minor groove binding Hoechst 33258) and UV-Vis spectroscopy. The copper(II) compounds interact with the minor groove of the biomolecule, whereas weaker electrostatic interactions take place with the zinc(II) compounds. The spectroscopic data achieved for the two series of complexes (namely with copper(II) and zinc(II) as metal center) agree with the respective DNA-damage features observed by gel electrophoresis.

DNA recognition site of anticancer tinidazole copper(II) complexes

This paper describes the recognition process of tetrahedral [Cu^II(tnz)₂X₂] (X = Cl, Br) complexes by a DNA chain, analyzing the specific interaction between the DNA bases and backbone with the metal and the tinidazole (tnz) ligand. We identified the coordination of the copper metal center with one or two phosphates as the first recognition site for the tinidazole copper(II) complexes, while the ligands present partial intercalation into the minor groove. Also, we discuss a novel trigonal copper(I) tnz bromide complex, obtained by reducing the previously reported [Cu(tnz)₂Br₂]. This complex sheds light on the mechanism of action of tnz metal complexes as one of the most stable DNA-complex adducts depicts a trigonal geometry around the copper ion.

Coordination compounds with heterocyclic ester derivatives. Structural characterization and anti-proliferative activity

A series of new coordination compounds of cobalt(II), copper(II) and zinc(II) with heterocyclic ester derivatives (ethyl 4-methyl-5-imidazole-carboxylate (emizco), 1-(2-(phenylsulphonyl)ethyl)-4-imidazole carboxylate (semizco)) and methyl 5-(propylthio)-2-benzimidazolecarbamate (albendazole, abz) were synthesized. They were fully characterized by different techniques such as IR, UV-Vis-NIR, elemental analysis, molar conductivity and magnetic susceptibility. Additionally, X-ray crystal structures of semizco and its [Co(semizco)₂Cl₂]·2CH₃CN 10, [Co(smmizco)₂Br₂]·2CH₃CN 11 and [Cu(semizco)₂Br₂] 15 coordination compounds are analyzed. These compounds present lone pair SO⋯π interactions between the sulfone and the imidazolic ring. These ligands showed three coordination modes: monodentate, through an imidazolic nitrogen atom, or a bidentate chelating mode by a nitrogen and an oxygen atom from the ester group. The different coordination modes and the number of coordinated ligands gave rise to tetrahedral and octahedral compounds, or for [Cu(semizco)(μ-Br)Br]_n·0.5H₂O 7 a square base pyramidal geometry. A cytotoxic study was carried out with the free ligands and their copper(II) and zinc(II) halide coordination compounds on HeLa (cervix-uterine), MCF-7 (breast), HCT-15 (colon), PC3 (prostate) human carcinoma cell lines and L929 mouse fibroblast (healthy cells). A TUNEL assay (terminal deoxynucleotidyl transferase dUTP nick end labeling) was performed with the most active copper(II) compounds to determine if cell death was by apoptosis.

Fluconazole induces ROS in Cryptococcus neoformans and contributes to DNA damage in vitro

Pathogenic basidiomycetous yeast, Cryptococcus neoformans, causes fatal meningitis in immunocompromised individuals. Fluconazole (FLC) is a fungistatic drug commonly administered to treat cryptococcosis. Unfortunately, FLC-resistant strains characterized by various degree of chromosomal instability were isolated from clinical patients. Importantly, the underlying mechanisms that lead to chromosomal instability in FLC-treated C. neoformans remain elusive. Previous studies in fungal and mammalian cells link chromosomal instability to the reactive oxygen species (ROS). This study provides the evidence that exposure of C. neoformans to FLC induces accumulation of intracellular ROS, which correlates with plasma membrane damage. FLC caused transcription changes of oxidative stress related genes encoding superoxide dismutase (SOD1), catalase (CAT3), and thioredoxin reductase (TRR1). Strikingly, FLC contributed to an increase of the DNA damage in vitro, when complexed with iron or copper in the presence of hydrogen peroxide. Strains with isogenic deletion of copper response protein metallothionein were more susceptible to FLC. Addition of ascorbic acid (AA), an anti-oxidant at 10 mM, reduced the inhibitory effects of FLC. Consistent with potential effects of FLC on DNA integrity and chromosomal segregation, FLC treatment led to elevated transcription of RAD54 and repression of cohesin-encoding gene SCC1. We propose that FLC forms complexes with metals and contributes to elevated ROS, which may lead to chromosomal instability in C. neoformans.