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.

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.

Preclinical evidences of safety of a new synthetic adjuvant to formulate with the influenza human vaccine: absence of subchronic toxicity and mutagenicity.

Context: Influenza is a severe, life-threatening viral disease that can be prevented by vaccination. However, the anti-influenza human vaccine failed to show the required efficacy both in infants under 5 years old and in the elder population, who are among those with the highest risk of developing severe complications after influenza infection. Therefore, it is of high importance to improve the vaccine efficacy and ensure its safety in these susceptible populations. GK-1, a novel 18-aa peptide adjuvant, has been proved to increase the immunogenicity of the human influenza vaccine in both young and aged mice. Objective: A preclinical study of the toxicity profile of GK-1 following the World Health Organization guidelines to support its use was herein conducted. Material and methods: GK-1 was synthetically produced following Good Manufacturing Practices. The toxicological evaluation of GK-1 peptide was performed in rats after repeated dose-ranging trials by the subcutaneous route. The mutagenic potential of GK-1 was assessed by the micronucleus, chromosomal aberration, and Ames tests, in accordance with OECD Guidelines. Results: GK-1 did not show toxic effects at doses up to 12.5mg/kg, corresponding to 25 times the dose intended for human use. No indications of mutagenic potential were observed. GK-1 after dermal administration was well tolerated locally. Conclusion: The efficacy of GK-1 to improve influenza vaccine protection, along with the absence of toxicity and mutagenicity, as reported herein, support the evaluation of this peptide in a clinical trial as a novel adjuvant for human use.

Functional Effects of Prebiotic Fructans in Colon Cancer and Calcium Metabolism in Animal Models.

Inulin-type fructans are polymers of fructose molecules and are known for their capacity to enhance absorption of calcium and magnesium, to modulate gut microbiota and energy metabolism, and to improve glycemia. We evaluated and compared the effects of Chicory inulin "Synergy 1®" and inulin from Mexican agave "Metlin®" in two experimental models of colon cancer and bone calcium metabolism in mice and rats. Inulins inhibited the development of dextran sulfate sodium-induced colitis and colon cancer in mice; these fructans reduced the concentration of tumor necrosis factor alpha and prevented the formation of intestinal polyps, villous atrophy, and lymphoid hyperplasia. On the other hand, inulin treatments significantly increased bone densitometry (femur and vertebra) in ovariectomized rats without altering the concentration of many serum biochemical parameters and urinary parameters. Histopathology results were compared between different experimental groups. There were no apparent histological changes in rats treated with inulins and a mixture of inulins-isoflavones. Our results showed that inulin-type fructans have health-promoting properties related to enhanced calcium absorption, potential anticancer properties, and anti-inflammatory effects. The use of inulin as a prebiotic can improve health and prevent development of chronic diseases such as cancer and osteoporosis.

Suppression of the tert-butylhydroquinone toxicity by its grafting onto chitosan and further cross-linking to agavin toward a novel antioxidant and prebiotic material.

The enzyme-mediated grafting of tert-butylhydroquinone (TBHQ) onto chitosan and further crosslinking to agave inulin (agavin) has been successfully achieved in a mild and non-toxic two-step route. The resulting products were characterized by nuclear magnetic resonance (NMR) and Infra-red spectroscopies to assess the molecular structure. The study of acute oral toxicity in mice revealed no adverse short-term effects of consumption in the synthesized materials with non-toxicity evidence until 2000 mg/kg through an oral acute administration. Importantly, this study proves that the compound maintains the radical scavenging capacity of the phenolic antioxidant upon ferric-reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays with a measured half-maximal inhibitory concentration (IC50) for the best case of 1.54 g/L based on inhibition of 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid diammonium salt (ABTS). Additionally, the novel compound presented high prebiotic activities as ascertained in the presence of lactic acid bacteria (LAB).

2,6-Bis(2,6-diethylphenyliminomethyl)pyridine coordination compounds with cobalt(II), nickel(II), copper(II), and zinc(II): synthesis, spectroscopic characterization, X-ray study and in vitro cytotoxicity.

Coordination compounds with cobalt(II), nickel(II), copper(II) and zinc(II) and the ligand 2,6-bis(2,6-diethylphenyliminomethyl)pyridine (L) were synthesized and fully characterized by IR and UV-Vis-NIR spectroscopy, elemental analysis, magnetic susceptibility and X-ray diffraction for two representative cases. These novel compounds were designed to study their activity as anti-proliferative drugs against different human cancer cell lines. The tridentate ligand forms heptacoordinated compounds from nitrate metallic salts, where the nitrate acts in a chelating form to complete the seven coordination positions. In vitro cell growth inhibition was measured for Co(II), Cu(II) and Zn(II) complexes, as well as for the free ligand. Upon coordination, the IC50 value of the transition-metal compounds is improved compared to the free ligand. The copper(II) and zinc(II) compounds are the most promising candidates for further in vitro and in vivo studies. The activity against colon and prostate cell lines merits further research, in views of the limited therapeutic options for such cancer types.

Cytotoxic activity, X-ray crystal structures and spectroscopic characterization of cobalt(II), copper(II) and zinc(II) coordination compounds with 2-substituted benzimidazoles.

Herein we present the synthesis, structural and spectroscopic characterization of coordination compounds of cobalt(II), copper(II) and zinc(II) with 2-methylbenzimidazole (2mbz), 2-phenylbenzimidazole (2phbz), 2-chlorobenzimidazole (2cbz), 2-benzimidazolecarbamate (2cmbz) and 2-guanidinobenzimidazole (2gbz). Their cytotoxic activity was evaluated using human cancer cell lines, PC3 (prostate), MCF-7 (breast), HCT-15 (colon), HeLa (cervic-uterine), SKLU-1 (lung) and U373 (glioblastoma), showing that the zinc(II) and copper(II) compounds [Zn(2mbz)(2)Cl(2)].0.5H(2)O, [Zn(2cmbz)(2)Cl(2)].EtOH, [Cu(2cmbz)Br(2)].0.7H(2)O and [Cu(2gbz)Br(2)] had significant cytotoxic activity. The isostructural cobalt(II) complexes showed not significant activity. The cytotoxic activity is related to the presence of halides in the coordination sphere of the metal ion. Recuperation experiments with HeLa cells, showed that the cells recuperated after removing the copper(II) compounds and, on the contrary, the cells treated with the zinc(II) compounds did not. These results indicate that the mode of action of the coordination compounds is different.