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.

Caveats of chimpanzee ChAdOx1 adenovirus-vectored vaccines to boost anti-SARS-CoV-2 protective immunity in mice

Several COVID-19 vaccines use adenovirus vectors to deliver the SARS-CoV-2 spike (S) protein. Immunization with these vaccines promotes immunity against the S protein, but against also the adenovirus itself. This could interfere with the entry of the vaccine into the cell, reducing its efficacy. Herein, we evaluate the efficiency of an adenovirus-vectored vaccine (chimpanzee ChAdOx1 adenovirus, AZD1222) in boosting the specific immunity compared to that induced by a recombinant receptor-binding domain (RBD)-based vaccine without viral vector. Mice immunized with the AZD1222 human vaccine were given a booster 6 months later, with either the homologous vaccine or a recombinant vaccine based on RBD of the delta variant, which was prevalent at the start of this study. A significant increase in anti-RBD antibody levels was observed in rRBD-boosted mice (31-61%) compared to those receiving two doses of AZD1222 (0%). Significantly higher rates of PepMix™- or RBD-elicited proliferation were also observed in IFNγ-producing CD4 and CD8 cells from mice boosted with one or two doses of RBD, respectively. The lower efficiency of the ChAdOx1-S vaccine in boosting specific immunity could be the result of a pre-existing anti-vector immunity, induced by increased levels of anti-adenovirus antibodies found both in mice and humans. Taken together, these results point to the importance of avoiding the recurrent use of the same adenovirus vector in individuals with immunity and memory against them. It also illustrates the disadvantages of ChAdOx1 adenovirus-vectored vaccine with respect to recombinant protein vaccines, which can be used without restriction in vaccine-booster programs. KEY POINTS: • ChAdOx1 adenovirus vaccine (AZD1222) may not be effective in boosting anti-SARS-CoV-2 immunity • A recombinant RBD protein vaccine is effective in boosting anti-SARS-CoV-2 immunity in mice • Antibodies elicited by the rRBD-delta vaccine persisted for up to 3 months in mice.

AS1411 Nucleolin-Specific Binding Aptamers Reduce Pathological Angiogenesis through Inhibition of Nucleolin Phosphorylation

Proliferative retinopathies produces an irreversible type of blindness affecting working age and pediatric population of industrialized countries. Despite the good results of anti-VEGF therapy, intraocular and systemic complications are often associated after its intravitreal use, hence novel therapeutic approaches are needed. The aim of the present study is to test the effect of the AS1411, an antiangiogenic nucleolin-binding aptamer, using in vivo, ex vivo and in vitro models of angiogenesis and propose a mechanistic insight. Our results showed that AS1411 significantly inhibited retinal neovascularization in the oxygen induced retinopathy (OIR) in vivo model, as well as inhibited branch formation in the rat aortic ex vivo assay, and, significantly reduced proliferation, cell migration and tube formation in the HUVEC in vitro model. Importantly, phosphorylated NCL protein was significantly abolished in HUVEC in the presence of AS1411 without affecting NFκB phosphorylation and -21 and 221-angiomiRs, suggesting that the antiangiogenic properties of this molecule are partially mediated by a down regulation in NCL phosphorylation. In sum, this new research further supports the NCL role in the molecular etiology of pathological angiogenesis and identifies AS1411 as a novel anti-angiogenic treatment.

Anti-proliferative, pro-apoptotic and anti-invasive effect of the copper coordination compound Cas III-La through the induction of reactive oxygen species and regulation of Wnt/β-catenin pathway in glioma

Gliomas are the most aggressive neoplasms that affect the central nervous system, being glioblastoma multiforme (GBM) the most malignant. The resistance of GBM to therapies is attributed to its high rate of cell proliferation, angiogenesis, invasion, and resistance to apoptosis; thus, finding alternative therapeutic approaches is vital. In this work, the anti-proliferative, pro-apoptotic, and anti-invasive effect of the copper coordination compound Casiopeina III-La (Cas III-La) on human U373 MG cells was determined in vitro and in vivo. Our results indicate that Cas III-La exerts an anti-proliferative effect, promoting apoptotic cell death and inactivating the invasive process by generating reactive oxygen species (ROS), inactivating GSK3β, activating JNK and ERK, and promoting the nuclear accumulation of β-catenin. The inhibition of ROS generation by N-acetyl-l-cysteine not only recovered cell migration and viability, but also reduced β-catenin accumulation and JNK and ERK activation. Additionally, Cas III-La significantly reduced tumor volume, cell proliferation and mitotic indices, and increased the apoptotic index in mice xenotransplanted with U373 glioma cells. Thus, Cas III-La is a promising agent to treat GBM.

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.

Toxicity Evaluation of a Novel Rapamycin Liposomal Formulation After Subconjunctival and Intravitreal Injection

Purpose: Safety and toxicity evaluation of a novel, liposome-encapsulated rapamycin formulation, intended for autoimmune ocular disorders. Methods: The formulation was assessed by micronucleus polychromatic erythrocyte production, irritability by Hen's Egg Test-Chorioallantoic Membrane (HET CAM), sterility, and pyrogenicity testing. Subconjunctival (SCJ) and intravitreal (IVT) administration of the formulation were performed to evaluate subacute and acute toxicity, respectively. Differences between groups in biochemical and hematological parameters were evaluated by analysis of variance and t-tests. Numeric score was assigned to histopathological classification. Electroretinography (ERG) testing was also performed. Data were analyzed by a 1 way no parametric Kruskal-Wallis and the Mann-Whitney tests. Significance was considered when P < 0.05. Results: No significant toxicity directly related to the preparation was detected. Micronucleus count, mucous irritation score, and pyrogenicity results were negative. Pathology demonstrated no damage related to the formulation after SCJ injection. After IVT injection, only lens injury associated with technique was observed. Retinal function was also conserved in ERG. Conclusions: The preparation evaluated offers a good toxicity and safety profile when injected in a SCJ or IVT manner in an animal model. A clinical trial conducted in humans is highly warranted, as it could reveal an alternative immunosuppressive treatment for ophthalmological immune-mediated pathologies.

Synthesis, characterization and cytotoxic activity of tioconazole coordination compounds with nickel(II), palladium(II) and platinum(II)

Coordination compounds of nickel(II), palladium(II) and platinum(II) with tioconazole (tcnz) were synthesized and characterized by infrared, UV-Vis-NIR, elemental analysis, molar conductivity, magnetic susceptibility, mass spectrometry, NMR spectroscopy and X- ray diffraction. Tioconazole presented a monodentate coordination mode, through the nitrogen atom of the imidazolic ring. The NiII compounds stabilized an octahedral geometry. In [Ni(tcnz)2(NO3)2].H2O the coordinated nitrate presented a bidentate coordination mode, while for the [Ni(tcnz)2(OAc)2].3H2O compound, the acetate behaves as a bridging ligand. When different molar ratios were used on the reaction synthesis, three or six ligands were coordinate to the nickel(II) atom, [Ni(tcnz)3Br2(H2O)], [Ni(tcnz)6]Cl2 and [Ni(tcnz)6]Br2. The palladium(II) and platinum(II) compounds, [Pd(tcnz)2Cl2], [Pt(tcnz)2Cl2].2H2O and [Pd(tcnz)2(OAc)2], stabilized a trans-square planar geometry. The compounds [Ni(tcnz)6]X2 give place to 3D supramolecular arrangements through hydrogen bonding (X∙∙∙H, X = Cl and Br) and p∙∙∙p stacking interactions, between the six membered rings of neighbouring molecules. The in vitro cytotoxic activity of the synthesized compounds was studied in four different human carcinoma cell lines: HCT-15 (colon), HeLa (cervix-uterine), MCF-7 (breast) and PC-3 (prostate).

Exposure to bisphenol A: current levels from food intake are toxic to human cells

In the present work, cell lines of different origin were exposed to BPA levels from food intake reported elsewhere. Specifically, we used an in vitro assay to determine cytotoxicity of BPA in three cell lines: MCF7 (breast cancer), PC3 (prostate cancer) and 3T3-L1 (mouse fibroblast). Cytotoxic effects were observed at concentrations higher than 50 μg/mL which is above the involuntary exposure level of BPA described before in fresh, canned and frozen foods and beverages. Furthermore, medial inhibitory concentrations (IC50) of 85.17 μg/mL and 88.48 μg/mL were observed for PC3 and 3T3-L1, respectively, and a slightly lower IC50 of 64.67 μg/mL for MCF7. These results highlight BPA's toxicity potential at current levels from food intake. The cell line-dependent divergent response to BPA reported herein is discussed.

Antineoplastic Evaluation of Two Mixed Chelate Copper Complexes (Casiopeínas®) in HCT-15 Xenograft Model

Casiopeínas^® is a family of copper complexes with the general formulae [Cu(N-N)(N-O)]NO₃ and [Cu(N-N)(O-O)]NO₃; where N-N = substituted aromatic diimine (2,2’-bipyridine (<em>bipy</em>) or 1,10-phenanthroline (<em>phen</em>)); N-O = α-aminoacidate or a peptide; and O-O = acetylacetonate (<em>acac</em>) or salicylaldehydate. These compounds have shown antiproliferative activity in vitro and antitumor activity in several mouse models with promissory results. Efforts have been done in order to understand the role played by ligands in the biological activity. With the aim of finding out the effect of secondary ligand (N-O or O-O), two of the most active complexes <em>in vitro</em> assays were selected to perform in vivo study on HCT-15 colon adenocarcinoma xenograft model. Both complexes, [Cu(3,4,7,8-tetramethyl-1,10-phen anthroline)(glycinato)]NO₃ (<strong>1</strong>) and [Cu(3,4,7,8-tetramethyl-1,10-phenanthroline)(acetylacetonato)]NO₃ (<strong>2</strong>) share the same diimine ligand and the secondary ligand changes from glycinate (<em>gly</em>) to <em>acac</em>. Results show that 2 is effective to reduce tumor size but <strong>1</strong> does not achieve the values required according to protocols, revealing an important difference between compounds attributable to change of ligand from <em>gly</em> to <em>acac</em>.

Process signatures in glatiramer acetate synthesis: structural and functional relationships

Glatiramer Acetate (GA) is an immunomodulatory medicine approved for the treatment of multiple sclerosis, whose mechanisms of action are yet to be fully elucidated. GA is comprised of a complex mixture of polypeptides with different amino acid sequences and structures. The lack of sensible information about physicochemical characteristics of GA has contributed to its comprehensiveness complexity. Consequently, an unambiguous determination of distinctive attributes that define GA is of highest relevance towards dissecting its identity. Herein we conducted a study of characteristic GA heterogeneities throughout its manufacturing process (process signatures), revealing a strong impact of critical process parameters (CPPs) on the reactivity of amino acid precursors; reaction initiation and polymerization velocities; and peptide solubility, susceptibility to hydrolysis, and size-exclusion properties. Further, distinctive GA heterogeneities were correlated to defined immunological and toxicological profiles, revealing that GA possesses a unique repertoire of active constituents (epitopes) responsible of its immunological responses, whose modification lead to altered profiles. This novel approach established CPPs influence on intact GA peptide mixture, whose physicochemical identity cannot longer rely on reduced properties (based on complete or partial GA degradation), providing advanced knowledge on GA structural and functional relationships to ensure a consistent manufacturing of safe and effective products.

Redox-active and DNA-binding coordination complexes of clotrimazole

The coordination compounds bind to DNA by two different binding modes depending on the concentration, sequence of the DNA, and the structure of the complex.

Casiopeína IIgly-induced oxidative stress and mitochondrial dysfunction in human lung cancer A549 and H157 cells

Casiopeínas are a series of mixed chelate copper complexes that are being evaluated as anticancer agents. Their effects in the cell include oxidative damage and mitochondrial dysfunction, yet the molecular mechanisms leading to such effects remain unclear. We tested whether [Cu(4,7-dimethyl-phenanthroline)(glycinate)]NO(3) (Casiopeína IIgly or Cas IIgly) could alter cellular glutathione (GSH) levels by redox cycling with GSH to generate ROS and cellular oxidative stress. Cas IIgly induced a dramatic drop in intracellular levels of GSH in human lung cancer H157 and A549 cells, and is able to use GSH as source of electrons to catalyze the Fenton reaction. In both cell lines, the toxicity of Cas IIgly (2.5-5 microM) was potentiated by the GSH synthesis inhibitor l-buthionine sulfoximine (BSO) and diminished by the catalytic antioxidant manganese(III) meso-tetrakis(N,N'-diethylimidazolium-2-yl)porphyrin (MnTDE-1,3-IP(5+)), thus supporting an important role for oxidative stress. Cas IIgly also caused an over-production of reactive oxygen species (ROS) in the mitochondria and a depolarization of the mitochondrial membrane. Moreover, Cas IIgly produced mitochondrial DNA damage that resulted in an imbalance of the expression of the apoproteins of the mitochondrial respiratory chain, which also can contribute to increased ROS production. These results suggest that Cas IIgly initiates multiple possible sources of ROS over-production leading to mitochondrial dysfunction and cell death.

Antiproliferative activity and QSAR study of copper(II) mixed chelate [Cu(N-N)(acetylacetonato)]NO3 and [Cu(N-N)(glycinato)]NO3 complexes, (Casiopeínas)

Mixed chelate copper(II) complexes patented and mark title registered as Casiopeínas are antineoplastic agents with general formulas [Cu(N-N)(alpha-l-amino acidato)]NO(3) and [Cu(N-N)(O-O)]NO(3), where the N-N donor is an aromatic substituted diimine (1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy)) and the O-O donor is acetylacetonate (acac) or salicylaldehydate (salal). In the present work, the series of complexes [Cu(N-N)(acac)]NO(3) and [Cu(N-N)(gly)]NO(3) with several substituents on the diimine ligand were selected to perform a quantitative structure-activity relationship (QSAR) study. Two main analysis were performed: (1) the study of the influence of the substituents on diimine ligand on physicochemical properties such as half-wave potential (E(1/2)) and their relationship with medial lethal dose (LD50) or medial inhibitory concentration (IC50) on several tumor cell lines and (2) the study of the influence of the secondary ligand when acac is changed for glycinate (gly). Results showed that the presence of the central fused aromatic ring in the phen containing complexes is necessary to preserve the antiproliferative activity. The QSAR equations showed a strong relationship between the IC50 and E(1/2); the most active complexes are the weaker oxidants. The change of secondary ligand from acac to gly has less influence on biological activity than the changes on the diimine ligand.

Assessment of Acute Respiratory and Cardiovascular Toxicity of Casiopeinas in Anaesthetized Dogs

The 99 lethal dose in an acute toxicity study of two anticancer novel molecules named casiopeinas((R)) in dogs was calculated to be 200 mg/m(2) for casiopeina III-ia and 160 mg/m(2) for casiopeina IIgly. Considering therapeutic dose ranges from 3.6 to 18 mg/m(2) for the former and 1.2 to 3 mg/m(2) for the latter, true therapeutic margin of safety varies from 4.7 to 23.6 mg/m(2) and from 20 to 50 mg/m(2), respectively. For both casiopeinas intravenous administration of the corresponding lethal dose in 100 ml of 5% dextrose solution in a time period of 30 min. induced death after an almost uneventful latency time period of 30-50 min. Then, after an apparently sudden onset, changes in blood gases indicated respiratory distress (PO(2) from 82.5% to 26.5% for casiopeina III-ia and from 88.6% to 37.5% for casiopeina IIgly; end-tidal CO(2) from 38 to 8.1 mmHg for the first and from 35.1 to 11.2 mmHg for the second, this was almost simultaneously confirmed by the onset of tachypnoea (from 16 to almost 60 breaths/min. for both casiopeinas) and by a drop in arterial blood pressure (from 117 to 51 mmHg for casiopeina III-ia and from 108 to 49 mmHg for casiopeina IIgly). Reflex tachycardia occurs at the beginning of intravenous administration followed by bradycardia a few minutes later (from 158 to 63 beats/min. for casiopeina III-ia and from 148 to 56 beats/min. for casiopeina IIgly). Finally, cardiac arrest occurred no later than 25 min. towards the end of these events lung oedema appeared as fluid dripping from the endotracheal tube. Death occurred in a mean of 15 +/- 5 min. S.D. from the beginning of the end of the latency period. For both casiopeina's data allow the speculation that lung oedema is caused by a joined toxicity to the lung capillary bed, and particularly to the heart. Carvedilol premedication for 8 days delayed the outcome of lung oedema by approximately 8 hr but could not prevent it.

Casiopeina III-ia induces apoptosis in HCT-15 cells in vitro through caspase-dependent mechanisms and has antitumor effect in vivo

The aim of this study was to evaluate the in vitro and in vivo effects of the new chemotherapy agent Casiopeina III-ia [(4,4'-dimethyl-2,2'-bipiridine)(acetylacetonate) Copper (II) nitrate] on HCT-15 (p53-/-) colon cellular line. In vitro, the drug reduced the viability and induced necrosis and apoptosis in a dose dependent manner, without affecting cell cycle phases. Apoptosis was related to Bax increasing levels, suggesting a caspase-dependent mechanism of death, as verified by nucleosomal fragmentation of DNA. In vivo, the antitumor activity of Casiopeina III-ia was tested in HCT-15 cells transplanted to nude mice. In this study we will show that the novel antineoplastic agent Casiopeina III-ia is active on this colon tumor line, setting out as a good candidate for the treatment of colon tumors refractory to chemotherapy.

Cas IIgly induces apoptosis in glioma C6 cells in vitro and in vivo through caspase-dependent and caspase-independent mechanisms

In this work, we investigated the effects of Casiopeina II-gly (Cas IIgly)--a new copper compound exhibiting antineoplastic activity--on glioma C6 cells under both in vitro and in vivo conditions, as an approach to identify potential therapeutic agents against malignant glioma. The exposure of C6 cells to Cas IIgly significantly inhibited cell proliferation, increased reactive oxygen species (ROS) formation, and induced apoptosis in a dose-dependent manner. In cultured C6 cells, Cas IIgly caused mitochondrio-nuclear translocation of apoptosis induction factor (AIF) and endonuclease G at all concentrations tested; in contrast, fragmentation of nucleosomal DNA, cytochrome c release, and caspase-3 activation were observed at high concentrations. Administration of N-acetyl-L-cystein, an antioxidant, resulted in significant inhibition of AIF translocation, nucleosomal DNA fragmentation, and caspase-3 activation induced by Cas IIgly. These results suggest that caspase-dependent and caspase-independent pathways both participate in apoptotic events elicited by Cas IIgly. ROS formation induced by Cas IIgly might also be involved in the mitochondrio-nuclear translocation of AIF and apoptosis. In addition, treatment of glioma C6-positive rats with Cas IIgly reduced tumor volume and mitotic and cell proliferation indexes, and increased apoptotic index. Our findings support the use of Cas IIgly for the treatment of malignant gliomas.

Toxic effects of copper-based antineoplastic drugs (Casiopeinas) on mitochondrial functions

To elucidate some of the subcellular and biochemical mechanisms of toxicity of metal-based antineoplastic drugs, mitochondria and cells were exposed to Casiopeinas), a new class of copper-based compounds with high antineoplastic activity. The rates of respiration and swelling, the H(+) gradient, and the activities of succinate (SDH) and 2-oxoglutarate dehydrogenases (2-OGDH) and ATPase were measured in mitochondria isolated from rat liver, kidney, heart, and hepatoma AS-30D. Also, oligomycin-sensitive respiration and ATP content in hepatoma AS-30D cells were determined. Casiopeinas) (CS) II-gly and III-i inhibited the rates of state 3 and uncoupled respiration in mitochondria. CS II was 10 times more potent than CS III. The sensitivity to CS II was 4-5-fold higher in mitochondria incubated with 2-OG than with succinate. Thus, at low concentrations (< or =10 nmol (mg protein)(-1); 10 microM), CS II disturbed mitochondrial functions only when 2-OG was present, due to a specific inhibition of 2-OGDH. At high concentrations (> or =15nmol (mg protein)(-1)), CS II-induced stimulation of basal respiration, followed by a strong inhibition, which correlated with K(+)-dependent swelling and cytochrome c release, respectively; K(+)-channel openers induce a similar mitochondrial response. Mitochondria from liver, kidney and hepatoma showed a similar sensitivity towards CS II, whereas heart mitochondria were more resistant. Oxidative phosphorylation and ATP content were also decreased in tumor cells by CS II. The data suggested that CS affected several different mitochondrial sites, bringing about inhibition of respiration and ATP synthesis, which could compromise energy-dependent processes such as cellular duplication.

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.