Approach on the Electrochemical Reactivity of Poly-L-Glutamic Acid Against Doxorubicin and Its Application in the Development of a Voltammetric Sensor

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

Nitro derivatives and other constituents of Aristolochia melastoma

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

Piperamides and their derivatives as potential anti-trypanosomal agents

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

Antinociceptive profile of 2,3,6-trisubstituted piperidine alkaloids: 3-O-acetyl-spectaline and semi-synthetic derivatives of (-)-spectaline

In early studies, we have reported the antinociceptive profile of (-)-spectaline, a piperidine alkaloid from Cassia spectabilis. The present study describes the synthesis, the antinociceptive and anti-inflammatory activities of a series of 2,3,6-trialkyl-piperidine alkaloids: the natural (-)-3-O-acetyl-spectaline (LASSBio-755) and ten semi-synthetic spectaline derivatives. Structure-activity relationship (SARs) studies were performed. The structures of all synthesized derivatives were confirmed by means of nuclear magnetic resonance. Compounds were evaluated for their analgesic (acetic acid-induced mouse abdominal constrictions, hot-plate test, formalin-induced pain test) and some of them for the anti-inflammatory activities (carrageenan-induced rat paw edema test). The pharmacological results showed that several of the new compounds given orally at a dose of 100 mu mol/kg significantly inhibited the acetic acid-induced abdominal constrictions, but they were less active than (-)-spectaline. LASSBio-755 and LASSBio-776 were the most actives with 37% and 31.7% of inhibition. In the formalin-induced pain only LASSBio-776 was able to inhibit by 34.4% the paw licking response of the inflammatory phase, (-)-spectaline and LASSBio-755 did show any activity. In the carrageenan-induced rat paw edema, only (-)-spectaline exhibited an anti-inflammatory profile, showing an ED(50) value of 56.6 mu mol/kg. Our results suggest different mechanisms of action for the analgesic activity observed for LASSBio-776 (3-O-Bocspectaline), LASSBio-755 (3-O-acetyl-spectaline) and (-)-spectaline (LASSBio-754). The antinociceptive profile of some of the semi-synthetic spectaline derivatives extends our research concerning the chemical and pharmacological optimization of isolated natural products in the search of new drug candidates from brazilian biodiversity.

Phenolic Derivatives from Fruits of Dipteryx lacunifera DUCKE and Evaluation of Their Antiradical Activities

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Characterization of flavonoid and naphthopyranone derivatives from Eriocaulon ligulatum using liquid chromatography tandem mass spectrometry

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

Alkamides and phenethyl derivatives from Aristolochia gehrtii

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

Synthesis and thermal study of the barium complexes with 8-hydroxyquinolinate derivatives

In this present work, barium ion was reacted with different ligands which are 5,7-dibromo, 5,7-dichloro, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring and the obtained compounds were as follows: (I) Ba[(C9H4ONBr2)(2)].1.5H(2)O; (II) Ba[(C9H4ONCl2)(OH)]. 1H(2)O; (III) Ba[(C9H5ONI)(2)]. 1H(2)O and (IV) Ba[(C9H4ONICl)(2)]. 5H(2)O, respectively. The compounds were characterized by elemental analysis, infrared absorption spectrum (IR), inductively coupled plasma spectrometry (ICP), simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimeter (DSC).The final residue of the thermal decomposition was characterized as orthorhombic BaBr2 from (I); the intermediate residue, as a mixture of orthorhombic BaCO3 and BaCl2 and cubic BaO and the final residue, as a mixture of cubic and tetragonal BaO and orthorhombic BaCl2 (II); the intermediate residue, as orthorhombic BaCO3 and as a final residue, a mixture of cubic and tetragonal BaO from (III); and the intermediate residue, as a mixture of orthorhombic BaCO3 and BaCl2 and as a final residue, a mixture of cubic and tetragonal BaO and orthorhombic BaCl2 from (IV).

Surface pressure-area isotherms for Langmuir monolayers and a docking molecular orientation of perylene tetracarboxylic derivatives on a water surface

The surface pressure-molecular area (pi-A) isotherms for Langmuir monolayers of four perylenetetracarboxylic (PTCD) derivatives, measured with varying subphase temperatures and compression speeds, are reported. The behavior of these PTCD derivatives at the water-air interface is modeled using the rigid docking method. This approach is the first attempt to model the molecular orientation of PTCD on the water surface to be compared with experimental Langmuir isotherms. Through this methodology, it would be possible to anticipate aggregation and determine if favorable spatial orientations of perylenes are generated on the water surface. The pi-A isotherm experiments show that these molecules can support high surface pressures, indicating strong packing on the water surface and that the isotherms are compression speed independent but temperature dependent. The molecular orientation and stacking was further examined in Langmuir-Blodgett (LB) monolayers deposited onto glass and glass coated with Ag island films using UV-visible absorption and surface-enhanced fluorescence (SEF) measurements.

Effect of temperature on the interaction between the nonionic surfactant C(12)E(5) and poly(ethylene oxide) investigated by dynamic light scattering and fluorescence methods

The interaction between the nonionic surfactant C(12)E(5) and a high molar mass (M = 5.94 x 10(5)) poly(ethylene oxide) (PEG) in aqueous solution has been examined as a function of temperature by dynamic light scattering and fluorescence methods over a broad concentration range. Clusters of small surfactant micelles form within the PEO coil, leading to its extension. The hydrodynamic radius of the complex increases strongly with temperature as well as with the concentrations of surfactant and polymer. At high concentrations of the surfactant, the coil/micellar cluster complex coexists with free C(12)E(5) micelles in the solution. Fluorescence quenching measurements show a moderate micellar growth from 155 to 203 monomers in PEO-free solutions of C(12)E(5) over a wide concentration range (0.02-2.5%) at 8 degrees C. Below 0.25% C(12)E(5), the average aggregation number (N) of the micelles is smaller in the presence of PEO than in its absence. However, N increases with increasing surfactant concentration up to a plateau value of about 270 at about 1.2% (ca. 30 mM) C(12)E(5). At high surfactant concentrations, N is larger in the presence of polymer than in its absence, a finding which is connected to a significant lowering of the clouding temperature due to the PEO at these compositions. Similar results of increasing aggregation number followed by a plateau were also found at a fixed concentration of surfactant (2.5%) and varied PEO.

Planar and UV written channel optical waveguides prepared with siloxane poly(oxyethylene)-zirconia organic-inorganic hybrids. Structure and optical properties

Organic-inorganic hybrids were prepared using ureapropyltriethoxysilane, methacryloxypropyltrimethoxysilane and acrylic acid modified zirconium(IV) n-propoxide precursors and were characterized by small angle X-ray scattering, X-ray diffraction and photoluminescence spectroscopy. The results indicate an effective interaction between the zirconium-based nanoparticles and the siliceous nanodomains that induces changes in the hybrids' emission features. Planar waveguides were obtained by spin-coating of the prepared sols on sodalime and silica substrates. Refractive index, thickness, number of propagating modes, and attenuation coefficient were measured at 543.5, 632.8 and 1550 nm by the prism coupling technique. The synergism between the two hybrid precursors resulted in monomode planar waveguides with low losses in the infrared ( from 0.6-1.1 dB cm(-1)) which also support a number of propagating modes in the visible ( losses from 0.4-1.5 dB cm(-1)). Channel waveguides were also obtained by UV photopatterning using amplitude or phase masks and propagating modes were observed at 1550 nm.

Electroactive LbL films of metallic phthalocyanines and poly(O-methoxyaniline) for sensing

Multilayered nanostructured films have been widely investigated for electrochemical applications as modified electrodes, including the layer-by-layer (LbL) films where properties such as thickness and film architecture can be controlled at the molecular level. In this study, we investigate the electrochemical features of LbL films of poly (o-methoxyaniline; POMA) and tetrasulfonated phthalocyanines containing nickel (NiTsPc) or copper (CuTsPc). The films displayed well-defined electroactivity, with redox pairs at 156 and 347 mV vs SCE, characteristic of POMA, which allowed their use as modified electrodes for detecting dopamine and ascorbic acid at concentrations as low as 10(-5) M.

Synthesis and reactivity in salt metathesis reactions of trivalent [La(Tp(Me2))(2)X] (X = Cl, I) complexes: crystal structures of [La(Tp(Me2))(2)Cl] and [La(Tp(Me2))(2)(kappa(2)-pz(Me2))]

Reaction of LaX3(THF)(n) (X = Cl, 1) with two equiv. of K(Tp(Me2)) gave good yields of the bis-Tp complexes [La(Tp(Me2))(2)X] (X = Cl (1); I (3)). However, the formation of 1 and 3 is always accompanied by significant amounts of La(Tp(Me2))(2)(kappa(2)-pz(Me2)) ([pz(Me2)](-) = 3,5-dimethyl-pyrazolato) (2). The pyrazolato complex 2, which presumably arises from decomposition of the [Tp(Me2)](-) moiety during salt metathesis, was independently prepared in good yield from 1 and in situ generated [pz(Me2)](-). The solid-state structures of 1 and 2 were determined by single-crystal X-ray diffraction studies. Subsequent reactions of halogeno-Tp(Me2) complexes 1 and 3 with various alkali metal salts MR (M = Li, R = CH2SiMe3, Ph, N(SiMe3)(2); M = K, R = OAr) gave M(Tp(Me2)) as the major product. Alternatively, the mono-Tp bis(aryloxide) derivatives [Ln(Tp(Me2))(OC6H2-2,6-'Bu-4-Me)(2)] (Ln = La (4); Nd (5)) were obtained in high yields by salt metathesis of [Ln(OC6H2-2,6-'Bu-4-Me)(3)] with one equiv. of K(Tp(Me2)). (C) 2004 Elsevier Ltd. All rights reserved.

Electrochemical reduction and determination of Cibacron Blue F3GA at poly-L-lysine modified glassy carbon electrode

The oxidation of a reactive dye, Cibacron Blue F3GA, CB, (C.I. 61211), widely used in the textile industries to color natural fibers, was studied by electrochemical techniques. The oxidation on glassy carbon electrode occurs in two steps at 2.0 < pH < 10 involving one electron transfer each to the amine group leading to the imide derivative. Stable films of poly-L-lysine (PLL) in the presence of glutaraldehyde (GA) 97.5%:2.5% on glassy carbon electrode can be used to detect low levels of dye using its oxidation peak at +0.75V by voltammetry. Linear calibration graphs were obtained for the CB reactive dye, from 1.0 X 10(-6) to 1.0 X 10(-5) mol L-1 in B-R buffer, pH 2.0, using a pre-concentration off-line during 10 min. The detection limit (3 sigma/slope) was calculated to be 4.5 X 10(-8) mol L-1. Films of PLL can readily be applied for the determination of CB dye bearing aminoanthraquinone as chromophore and chlorotriazinyl as reactive group at concentrations at least 100 times lesser than using a glassy carbon electrode without modification. The method described was applied for the determination of CB dye in tap water and raw water collected from the municipal treatment plant with a recovery of 89.2% +/- 5.4 and 88.0% +/- 6.5, respectively. (c) 2005 Elsevier Ltd. All rights reserved.

Catalysis and temperature dependence on the formation of ZnO nanoparticles and of zinc acetate derivatives prepared by the sol-gel route

The chemical and structural nature of powders prepared from the zinc acetate-derived precursor using the sol-gel route is discussed. The influence of the synthesis temperature and of the hydrolytic catalyst on the structural features of the powder is focused on the basis of X-ray powder diffraction (XRPD) and extended X-ray absorption fine structure (EXAFS) measurements and complemented with density and thermoanalysis (TG-DTA) results. EXAFS and XRPD results show that no-washed nanoparticulate powders are composed of a mixture of ZnO (wurtzite), zinc acetate, and zinc hydroxyacetate. The latter has a layered structure typical of hydroxy double salts (HDS). The main component of no-washed powders is always unreacted zinc acetate solid but the relative amount of the zinc-based compounds depends on the nature of the hydrolytic catalyst, hydrolysis ratio, and of synthesis temperature. According to the proportion of the three zinc-based compounds, three families of powders could be distinguished. The amount of ZnO nanoparticles (1.6 +/- 0.6 nm) decreases as the synthesis temperature increases, as the hydrolysis ratio decreases, or by changing from basic to acid catalysis. This finding suggests that the formation of zinc compounds is controlled by the equilibrium between hydrolysis-condensation and complexation-reprecipitation reactions.