Conformational analyses and docking studies of a series of 5-nitrofuran- and 5-nitrothiophen-semicarbazone derivatives in three possible binding sites of trypanothione and glutathione reductases

To explore three possible binding sites of trypanothione and glutathione reductase, namely, the active, the dimer interface and the coenzyme NADPH binding site, a series of eight compounds, nitrofurans and nitrothiophenes derivatives, were docked, using their crystallographic and modeled conformations. Docking results showed that, for both families and both enzymes, compounds are more likely to bind in the interface site, even though there is some probability of binding in the active site. These studies are in agreement with experimental data, which suggest that these class of compounds can act either as uncompetitive or mixed type inhibitors, and also with the finding that there is an alpha-helix which connects the active with the interface site, thus allowing charge transference between them. (c) 2005 Elsevier B.V. All rights reserved.

Plasma polymerized hexamethyldisiloxane: Discharge and film studies

Films were grown in hexamethyldisiloxane (HMDS)-argon mixtures in a diode sputtering system with a gold cathode. Quantitative optical emission spectroscopy (OES)-actinometry revealed that the electron density or mean electron energy (or both) increased with increasing Ar concentrations in the gas feed. Increasing concentrations of Ar produced greater sputtering of the cathode and hence greater plasma A u concentrations. Fragmentation of the HMDS molecule resulted in species such as CH, Fl, and Si which were detected by OES. Film deposition rate, as determined by optical interferometry, was found to be increased by the inclusion of Ar in the gas feed. Transmission electron microscopy revealed particles, probably of Au, embedded in the polymer films. Actinometric measurements of Au in the discharge and electron probe microscopy of the deposited material showed that film Au concentrations increase with increasing concentrations of Au in the plasma. A relatively low fragmentation of HMDS molecules in the de plasma was revealed by the very small Si-HIR absorption band which is usually prominent in spectra of plasma polymerized HMDS films.

Evaluation of serological tests for the diagnosis of Neospora caninum infection in dogs: Optimization of cut off titers and inhibition studies of cross-reactivity with Toxoplasma gondii

Diagnosis of Neospora caninum infection in dogs is based on serological assays such as the indirect fluorescent antibody test (IFAT) and enzyme-linked immunosorbent assays (ELISA). This study evaluated two serological tests (IFAT and ELISA) for the detection of IgG antibodies to N. caninum in 300 serum samples of dogs through the optimization of cut off titers by using the two-graph receiveroperating characteristic (TG-ROC) curve. In addition, the identification of major cross-reactive antigens with Toxoplasma gondii was investigated by inhibition ELISA and immunoblotting (IB) assays. IFAT and ELISA results showed 74% agreement, with a good negative concordance (P-neg=0.83), but a poor positive concordance (P-pos=0.42). The great majority (86%) of sera with positive concordant results (IFAT+/ELISA+) recognized at least two out of three N. caninum immunodominant antigens, particularly the 29-32 and 35-37 kDa bands. Optimization of cut off titers in IFAT and ELISA was performed considering the reactivity to at least two out of three N. caninum immunodominant antigens as infection markers, obtaining a titer of 50 for IFAT and 200 for ELISA. Seropositivity to N. caninuin was significantly associated with T gondii-seropositive samples, particularly in ELISA (55.4%). Inhibition ELISA curves for N. caninum showed a partial heterologous inhibition, indicating some degree of cross-reactivity between N. caninum and T gondii antigens. Inhibition IB assays showed a moderate heterologous inhibition for N. caninum antigens above 45-50 kDa. These results indicate that ELISA should be used critically when crude tachyzoite antigen preparations are employed, due to possible cross-reactivity with other related parasites as T gondii. Also, the cut off dilution of 1:50 in IFAT showed to be the most appropriated for N. caninum serology in dogs. Therefore, we suggest that N. caninum immunodominant antigens, specially the 17 and 29-32 kDa proteins, should be selected markers in serological assays for canine neosporosis. (c) 2006 Elsevier B.V. All rights reserved.

Pharmacological and toxicological studies of Drimys angustifolia Miers. (Winteraceae)

Drimys angustifolia Miers. (Winteraceae) is a Brazilian medicinal plant used as analgesic, antiulcer and anti-inflammatory without studies to assure its efficacy and safety Leaf and stem bark extracts were evaluated to determine the antiulcer, analgesic, antiinflammatory and antioxidant activities. Preliminary toxic effects and qualitative phytochemical profile were also performed. The antiulcer activity was detected in both extracts. Administration of the leaf extract at 250 mg/kg inhibited total lesion area by 76.50% (p < 0.01 in ethanol/HCl method), while carbenoxolone at 250 mg/kg reduced lesions by 69.48%. Stem bark extract (250 mg/kg) inhibited lesion by 81.42%, while carbenoxolone by 74.10%. Similar effects were observed in the ethanol-induced ulcer method, but no activity was observed in piroxican model. The effects involve nitric oxide in gastric protection, since the L-NAME treatment reversed the protection given by the extracts. Antioxidant effects suggest an involvement against oxidative stress. In the pain (writhing, tail-flick and hot-plate tests) and inflammation (carrageenan-induced paw edema) models, the extracts did not present any effect. The phytochemical studies demonstrated that both extracts contain flavonoids, saponins, glycosilated triterpenoids, fixed acids, cyanogenic glycosides, quinones, tannins, xanthone and steroidal aglycones. Toxicological studies showed that the extracts are safe at the effective antiulcer doses. (c) 2006 Elsevier B.V.. All rights reserved.

Synthesis and structural studies of (1,10-phenanthroline)(thiocyanate-N)-(triphenylphosphine)copper(I)

The compound (1,10-phenanthroline)(thiocyanate-N)(triphenylphosphine)copper(I), was synthesized and studied by IR spectroscopy and X-ray diffraction techniques. It is monomeric with the thiocyanate acting as a N-donor ligand. The copper atom shows a distorted tetrahedral coordination geometry.

The Role of the Eu3+ Concentration on the SrMoO4:Eu Phosphor Properties: Synthesis, Characterization and Photophysical Studies

SrMoO4 doped with rare earth are still scarce nowadays and have attracted great attention due to their applications as scintillating materials in electro-optical like solid-state lasers and optical fibers, for instance. In this work Sr1-xEuxMoO4 powders, where x = 0.01; 0.03 and 0.05, were synthesized by Complex Polymerization (CP) Method. The structural and optical properties of the SrMoO4:Eu3+ were analyzed by powder X-ray diffraction patterns, Fourier Transform Infra-Red (FTIR), Raman Spectroscopy, and through Photoluminescent Measurements (PL). Only a crystalline scheelite-type phase was obtained when the powders were heat-treated at 800 A degrees C for 2 h, 2 theta = 27.8A degrees (100% peak). The excitation spectra of the SrMoO4:Eu3+ (lambda(Em.) = 614 nm) presented the characteristic band of the Eu3 + 5L6 transition at 394 nm and a broad band at around 288 nm ascribed to the charge-transfer from the O (2p) state to the Mo (4d) one in the SrMoO4 matrix. The emission spectra of the SrMoO4:Eu3+ powders (lambda(Exc.) = 394 and 288 nm) show the group of sharp emission bands among 523-554 nm and 578-699 nm, assigned to the D-5(1)-> F-7(0,1and 2) and D-5(0)-> F-7(0,1,2,3 and 4), respectively. The band related to the D-5(0)-> F-7(0) transition indicates the presence of Eu3+ site without inversion center. This hypothesis is strengthened by the fact that the band referent to the D-5(0)-> F-7(2) transition is the most intense in the emission spectra.

Interaction between nitroheterocyclic compounds with beta-cyclodextrins: Phase solubility and HPLC studies

Chagas disease is a serious health problem for Latin America. Nitrofurazone (NF) and Hidroxymethylnitrofurazone (NFOH) are active against Trypanosoma cruzi. The effect of beta-cyclodextrin (beta-CD) and dimethyl-beta-cyclodextrin (DM-beta-CD) complexation on the UV absorption and retention time of nitrofurazone (NF) and its hydroxymethylated analog (NFOH) were studied in solution. The retention behavior was analyzed on a reversed phase C(18) column and the mobile phase used was acetonitrile-water (20/80 v/v), in which cyclodextrins (beta-CD or DM-beta-CD) were incorporated as a mobile phase additive. The decrease in the retention times of NF (or NFOH) with increasing concentration of HP-beta-CD enables the cleternnination of the complex stability constants by HPLC. A phase-solubility Study was performed. according to the method reported by Higuchi and Connors, to evaluate the changes of NF/NFOH in the complexation state, and the diagrams obtained suggested that it forms complexes with a stoichiometry of 1 : 1. This is an important Study for the characterization of potential formulations to be used as therapeutic options for the treatment of Chagas disease. (c) 2008 Elsevier B.V. All rights reserved.

Correlation between structural data and spectroscopic studies of a new beta-diketonate complex with trivalent europium and gadolinium

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Chemical and spectroscopic studies of a new palladium(II) complex with N-acetyl-L-cysteine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Calorimetric and SEM studies of PHB-PET polymeric blends

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Terbium(III) and dysprosium(III) 8-connected 3D networks containing 2,5-thiophenedicarboxylate anion: Crystal structures and photoluminescence studies

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Synthesis, characterization, crystal structure, and biological studies of vanadium complexes with glycolic acid

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Characterization and biological studies of a new platinum(II) complex with the amino acid L-alliin

Synthesis and characterization of a new Pt(II) complex with the amino acid L-alliin (S-allyl-L-cysteine sulfoxide, C(6)H(11)NO(3)S) are described. Elemental and mass spectrometric analyses of the solid complex are consistent with [PtCl(2)(alliin)], or [PtCl(2)(C(6)H(11)NO(3)S)]. (13)C nuclear magnetic resonance (NMR), [(1)H-(15)N] two dimensional (2D) NMR and infrared spectroscopy indicate coordination of the ligand to Pt(II) through the N and S atoms. The complex is very soluble in dimethyl sulfoxide. Biological analysis for evaluation of a potential cytotoxic effect of the complex was performed using HeLa cells derived from human cervical adenocarcinoma. The complex presented moderate cytotoxic activity, inducing about 40% cell death at a concentration of 400 mol L(-1).