Antigiardiasic activity of Cu(II) coordination compounds: Redox imbalance and membrane damage after a short exposure time.

Giardiasis is a widespread illness that affects inhabitants of underdeveloped countries, being children and seniors the highest risk population. The several adverse effects produced by current therapies besides its increasing ineffectiveness due to the appearance of resistant strains evidence the urgent need for new therapeutic approaches. We present the antigiardiasic effect of eight Cu(II) coordination compounds, which belong to the family Casiopeínas. Two of them, 4,7-diphenyl-1,10-phenanthroline(acetylacetonato)copper(II) nitrate (CasIII-Ha,36 µM) and 4,7-diphenyl-1,10-phenanthroline(glycinato)copper(II) nitrate (CasI-gly,36 µM) have shown the best antiproliferative effect in Giardia intestinalis trophozoite cultures, both with the higher lipophilic character of the series. The antiproliferative effect of these coordination compounds is attributable to its capacity to interact with the cellular membrane and to increase reactive oxygen species (ROS) concentration within the parasite since the first hours of exposure, (2-6 h). We found that these compounds mainly induced the cell death of trophozoites by apoptosis, contrary to metronidazole, which induces apoptosis and necrosis in the same ratio. The cytotoxic effects on lymphocytes and macrophages isolated from human peripheral blood allowed us to establish a selectivity index and in turn, identify and propose the best candidates to continue with the assays in animal models. The selected molecules do not include the most active compounds against trophozoites, instead of that, we propose the compounds 4',4'-dimethyl-2,2'-bipyridine(acetylacetonato)copper(II) nitrate (CasIII-ia,IC50 = 156 µM) and 4,7-dimethyl-1,10-phenanthroline(acetylacetonato) copper(II) nitrate (CasIII-Ea,IC50 = 125 µM), which possess an antiproliferative efficacy comparable with Metronidazole but also are those that produce the lowest effect on the viability of human lymphocytes and macrophages.

The π-back-bonding modulation and its impact in the electronic properties of Cu(II) antineoplastic compounds: an experimental and theoretical study.

A complete study of the electronic density distribution in antineoplastic mixed chelate complexes of the type [Cu(N-N)(glycinate)H2 O]NO3 (N-N=2,2'-bipyridine (bpy) (1), 4,4'-dimethyl-bpy (2), 5,5'-dimethyl-2,2'-bipyridine (3), 1,10-phenanthroline (phen) (4), 4-methyl-phen (5); 5-methyl-phen (6); 4,7-dimethyl-phen (7), 5,6-dimethyl-phen (8), and 3,4,7,8-tetramethyl-phen (9)), a family known as Casiopeínas, was carried out with cyclic voltammetry, EPR, and computational methods. Crystal structures of 1⋅H2 O, 2⋅H2 O, 3⋅H2 O, 6⋅H2 O, and 8⋅H2 O show the variability in the geometries adopted by the copper compounds in the solid state. Experimental properties are described employing electronic descriptors obtained from computational methods. The main descriptors found were: The total electronic population of the metal ion (N(Cu)), delocalization of the metal ion electrons over the donor atoms (Δ(Cu)), atomic dipolar moment (µ(Cu)), and the atomic quadrupole moment (Q(Cu)). It was found that π-back-bonding is the principal factor that modulates the distribution of the electron density around the metal ion. The electronic descriptors obtained from the computational approach can be used as electronic descriptors of inorganic compounds that have shown antiproliferative activities instead the experimental data, aiding the rational design of good candidates of metal-based drugs.

Aqua-(1,10-phenanthroline-κN,N')(valinato-κN,O)copper(II) nitrate dihydrate.

In the title compound, [Cu(C(5)H(10)NO(2))(C(12)H(8)N(2))(H(2)O)]NO(3)·2H(2)O, the Cu(II) atom displays a distorted square-pyramidal coordination (τ = 0.03) where the water mol-ecule occupies the apical position and the base is defined by the N atom, one of the O atoms from the valinate ligand, and both phenanthroline N atoms. The phenanthroline chelate ring plane is slightly distorted from planarity (r.m.s. deviation = 0.0057 Å), whereas the five-membered ring formed by the valinate ligand presents an envelope conformation with the N atom being the flap atom. The crystal packing is stabilized by O-H⋯O and N-H⋯O hydrogen-bonding inter-actions, creating a three-dimensional network superstructure.

Development and validation of a liquid chromatographic method for Casiopeina IIIi in rat plasma.

A sensitive and specific liquid chromatographic method using extraction with zinc sulfate has been developed for the determination of Casiopeina IIIi and validated over the linear range 5-100 microg/ml in 1 ml of rat plasma. The analysis was performed on a Symmetry C(18) (5 microm) column. The mobile phase was methanol: 0.01 M phosphate buffer pH 6.5 (40:60, v/v). The column effluent was monitored at 262 nm. The results showed that the assay is sensitive at 5 microg/ml. Maximum intra-day coefficient of variation was 10.6%. The recovery obtained in plasma was 87.2%. The method was used to perform protein binding studies by equilibrium dialysis in rat plasma and was found to be satisfactory.