Unusual 1,6-diphenyl-1,3,5-hexatriene (DPH) spectrophotometric behavior in water/ethanol and water/DMSO mixtures

The absorption spectra of DPH at fixed concentration do not change with water content in organic solvents. It exhibits monomer bands, such as those obtained in ethanol. The absorption did not change for solutions up to 54 and 46% of water in ethanol and DMSO, respectively, for [DPH] = 5.0 × 10-6 mol L-1 at 30 °C. However, at the same experimental conditions, a gradual sharp decay of the DPH fluorescence is observed. It is proposed that water molecules below these water concentration limits act as quenchers of the excited states of DPH. Stern-Volmer quenching constants by intensities measurements are 7.4 × 10-2 (water/ethanol) and 2.6 × 10-2 L mol-1 (water/DMSO). DPH lifetime measurements in the absence and presence of water resulted in 7.1 × 10-2 L mol-1 in water/ethanol, which pointed out that the process is a dynamic quenching by water molecules. For experiments using DPH as probe, this process can affect data, leading to misunderstanding interpretation.

Development and validation of a fast RP-HPLC method to determine the analogue of the thyroid hormone, 3,5,3 '-triiodothyroacetic acid (TRIAC), in polymeric nanoparticles

The objective of this work was to develop and validate a rapid Reversed-Phase High-Performance Liquid Chromatography method for the quantification of 3,5,3 '-triiodothyroacetic acid (TRIAC) in nanoparticles delivery system prepared in different polymeric matrices. Special attention was given to developing a reliable reproductive technique for the pretreatment of the samples. Chromatographic runs were performed on an Agilent 1200 Series HPLC with a RP Phenomenex (R) Gemini C18 (150 x 4, 6 mm i.d., 5 mu m) column using acetonitrile and triethylamine buffer 0.1% (TEA) (40 : 60 v/v) as a mobile phase in an isocratic elution, pH 5.6 at a flow rate of 1 ml min(-1). TRIAC was detected at a wavelength of 220 nm. The injection volume was 20 mu l and the column temperature was maintained at 35 degrees C. The validation characteristics included accuracy, precision, specificity, linearity, recovery, and robustness. The standard curve was found to have a linear relationship (r(2) - 0.9996) over the analytical range of 5-100 mu g ml(-1) . The detection and quantitation limits were 1.3 and 3.8 mu g ml(-1), respectively. The recovery and loaded TRIAC in colloidal system delivery was nearly 100% and 98%, respectively. The method was successfully applied in polycaprolactone, polyhydroxybutyrate, and polymethylmethacrylate nanoparticles.

Antioxidant Capacity of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles

The antioxidant capacity of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles was evaluated. The values of antioxidant capacities of compounds 2d and 2e were found to be, respectively, 2,700 +/- 150 and 3,135 +/- 230 TE by the ORAC method, corresponding to a significant antioxidant capacity.

Efficient sonochemical synthesis of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides

An Ultrasound-assisted preparation of a series of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides that proceeds via the efficient reaction of chalcones with aminoguanidine hydrochloride under clean conditions is described. (C) 2009 Elsevier B.V. All rights reserved.

Environmentally friendly sonocatalysis promoted preparation of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-1H-pyrazoles

An efficient and green synthesis of thiocarbamoyl-3,5-diaryl-4,5-dihydro-1 H-pyrazoles via the condensation of chalcones with thiosemicarbazide in ethanol and KOH under ultrasound irradiation is reported. The products were isolated in good yields after short reaction times. (C) 2009 Elsevier B.V. All rights reserved.

Mechanisms Involved in 3 `,5 `-Cyclic Adenosine Monophosphate-Mediated Inhibition of the Ubiquitin-Proteasome System in Skeletal Muscle

Although it is well known that catecholamines inhibit skeletal muscle protein degradation, the molecular underlying mechanism remains unclear. This study was undertaken to investigate the role of beta(2)-adrenoceptors (AR) and cAMP in regulating the ubiquitin-proteasome system (UPS) in skeletal muscle. We report that increased levels of cAMP in isolated muscles, promoted by the cAMP phosphodiesterase inhibitor isobutyl methylxanthine was accompanied by decreased activity of the UPS, levels of ubiquitin-protein conjugates, and expression of atrogin-1, a key ubiquitin-protein ligase involved in muscle atrophy. In cultured myotubes, atrogin-1 induction after dexamethasone treatment was completely prevented by isobutyl methylxanthine. Furthermore, administration of clenbuterol, a selective beta(2)-agonist, to mice increased muscle cAMP levels and suppressed the fasting-induced expression of atrogin-1 and MuRF-1, atrogin-1 mRNA being much more responsive to clenbuterol. Moreover, clenbuterol increased the phosphorylation of muscle Akt and Foxo3a in fasted rats. Similar responses were observed in muscles exposed to dibutyryl-cAMP. The stimulatory effect of clenbuterol on cAMP and Akt was abolished in muscles from beta(2)-AR knockout mice. The suppressive effect of beta(2)-agonist on atrogin-1 was not mediated by PGC-1 alpha (peroxisome proliferator-activated receptor-gamma coactivator 1 alpha known to be induced by beta(2)-agonists and previously shown to inhibit atrogin-1 expression), because food-deprived PGC-1 alpha knockout mice were still sensitive to clenbuterol. These findings suggest that the cAMP increase induced by stimulation of beta(2)-AR in skeletal muscles from fasted mice is possibly the mechanism by which catecholamines suppress atrogin-1 and the UPS, this effect being mediated via phosphorylation of Akt and thus inactivation of Foxo3. (Endocrinology 150: 5395-5404, 2009)

Transient disruption of liver gap junctional intercellular communication and induction of apoptosis after administration of 1,4-bis[2-(3,5 dichloropyridyloxy)]benzene in mice

Gap junctional intercellular communication (GJIC) and connexin expression (Cx26 and Cx32) in mouse liver were studied after administration of 4-bis[2-(3,5 dichloropyridyloxy)]benzene (TCPOBOP), a phenobarbital-like enzyme inducer. Female C57BI/6 mice were administered TCPOBOP (5.8 mg/kg BW) and euthanized 0, 24, 48 and 72 hours later. Liver samples were snap frozen, or fixed in formalin, or submitted to GJIC analysis. The proliferating cell nuclear antigen (PCNA) immunohistochemistry and the Western blotting for Cx26 and Cx32 were performed. After 48 and 72 h of drug administration the liver-to-body weight ratio was increased 70% and 117% (p < 0.0001), respectively. There were temporal-dependent alterations in liver histopathology and a significant increase in cell proliferation was noted after 48h and sustained after 72h, though to a lesser extent (p < 0.0001). In addition. TCPOBOP administration induced apoptosis, which appeared to be time-dependent showing statistical significance only after 72h (p < 0.0001). Interestingly, a transient disruption by nearly 50% of GJIC capacity was detected after 48 h of drug ingestion, which recovered after 72 h (p = 0.003). These GJIC changes were due to altered levels of Cx26 and Cx32 in the livers of TCPOBOP-treated mice. We concluded that a single administration of TCPOBOP transiently disrupted the levels of GJIC due to decreased expression of connexins and increased apoptotic cell death in mouse liver. (C) 2009 Elsevier GmbH. All rights reserved.

Structural and magnetic properties and hyperfine interaction in La(3.5)Ru(4)O(13) compound

Structural, magnetic and hyperfine interaction measurements have been carried out on the novel compound La(3.5)Ru(4)O(13) prepared under two different atmospheres (air and oxygen flow). This compound is formed in the orthorhombic structure (space group Pmmm, # 47). The coexistence of the triple-layered perovskite-type planes (quasi-2D structure) and the rutile-like slabs (1D structure) leads to interesting magnetic and electronic properties in this compound. The magnetic susceptibility of this system shows a peak at T similar to 47 K associated with antiferromagnetic interactions. The Curie-Weiss behaviour of the susceptibility provides an effective magnetic moment consistent with Ru ions in low-spin state. Perturbed angular correlation measurements carried out with (111)Cd probe in the temperature range 10-60 K reveal only quadrupole interactions and indicate the occurrence of structural distortions for T<40K. (C) 2009 Elsevier B.V. All rights reserved.

Ionic Recognition by 7-Nitro-1,3,5-triaza Adamantane: First Thermodynamic Study

A thermodynamic study involving 7-nitro-1,3,5-triaza adamantane, 1, and its interaction with metal cations in nonaqueous media is first reported. Solubility data of 1 in various solvents were used to derive the standard Gibbs energies of solution, Delta G(s)degrees in these solvents. The effect of solvation in the different media was assessed from the Gibbs energy of transfer taking acetonitrile as a reference solvent. (1)H NMR studies of the interaction of 1 and metal cations were carried out in CD(3)CN and CD(3)OD and the data are reported. Conductance measurements revealed that this ligand forms lead(II) or zinc complexes of 1: 1 stoichiometry in acetonitrile. It also revealed a stoichiometry of two molecules of 1 per mercury(II) and two cadmiu (II) ions per molecule of 1. The addition of silver salt to 1 led to the precipitation of the silver-1 complex which was isolated and characterized by X-ray crystallography. At variance with conductance measurements in solution, in the solid state the X-ray structure show`s a 1:1 stoichiometry in the Hg(II) complex. The themiodynamics of complexation of 1 and these cations provide a quantitative assessment of the selective behavior of this ligand for ions of environmental relevance.

Ultrasound promoted greener synthesis of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles

A rapid and cleaner procedure for the synthesis of a series of 2-(3,5-diaryl-45-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles under ultrasonic irradiation in ethanol is described. (C) 2010 Elsevier B.V. All rights reserved.

An insight into the beginning stage of the aqueous ring opening metathesis polymerization of exo,exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid with Ru(III) compounds: the consumption of Ru(III) species in the presence of carboxylic acids monitored by ESR spectroscopy

The presence of paramagnetic species in the aqueous ring opening metathesis polymerizations of the exo,exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid monomer with RuCl(3) and K(2)[RuCl(5)H(2)O] compounds was studied using ESR techniques. It was observed that the intensities of the Ru(III) signals in the ESR spectra decrease on the time scale of the induction period so that the ROMP can take place. The intensity of the Ru(III) signal almost disappeared 50 min after reacting with K(2)[RuCl(5)H(2)O] and after 100 mm in the case of RuCl(3). Reactions of the cis-[Ru(NH(3))(4)(H(2)O)(2)](tfms)(3) and [Ru(NH(3))(5)H(2)O](tfms)(3) complexes with the monomer and different organic compounds representing the organic functions in the monomer (furan, norbornene, but-2-ene-1,4-diol and formic, acetic, oxalic and maleic acids) were also monitored by ESR and UV/vis spectra. It was deduced that the organic acids provide the disappearance of the Ru(III) signal. The proton NMR relaxation times of the residual water in D(2)O for reactions with oxalic acid suggested that the presence of paramagnetic ions in the solution decreases along with

Metabólitos secundários das esponjas Aplysina fistularis e Dysidea sp. e atividade antituberculose da 11-cetofistularina-3

The present investigation reports the isolation of aeroplysinin-2, 2-(3,5-dibromo-4-methoxyphenyl)-N,N,N-trimethyletanamonium, 7,9-dibromo-10-hydroxy-8-methoxy-1-oxa-2-azaspiro[4.5]deca-2,6,8-trien-3-carboxylic acid and its methyl ester, 11-oxoaerothionin, aerothionin, 11-keto-12-hydroxyaerothionin, 11-ketofistularin-3 and fistularin-3 from Aplysina fistularis, as well as of furodysinin lactone and 9α,11α-epoxicholest-7-en-3β,5α,6α,10-tetrol-6-acetate from Dysidea sp. Although the extracts of both sponges displayed antituberculosis activity, only 11-ketofistularin-3 isolated from A. fistularis displayed antimycobacterial activity against Mycobacterium tuberculosis H34Rv, with MIC at 16 μg/mL and SI of 40, a result that reinforce that fistularin-3 derivatives are interesting leads for the development of antituberculosis drugs.

HPLC microfractionation of flavones and antioxidant (radical scavenging) activity of Saccharum officinarum L.

The antioxidant activity of sugarcane (Saccharum officinarum L.) juice towards DPPH reagent was determined (EC50) and the main compounds with radical scavenging activity in juice and leaves extracts were identified by HPLC-UV/PAD analysis combined with HPLC microfractionation monitored by TLC using β-carotene and DPPH as the detection reagents. In sugarcane leaves, luteolin-8-C-(rhamnosylglucoside) (1) was the most important compound with radical scavenging activity; in sugarcane juice, the flavones diosmetin-8-C-glucoside (2), vitexin (3) schaftoside (9), isoschaftoside (10) and 4',5'-dimethyl-luteolin-8-C-glucoside (11) were the most relevant compounds. The content of juice flavonoids (0.241 ± 0.001 mg total flavonoids/mL juice), comparable to other food sources of flavonoids, suggest the potential of sugarcane as a dietary source of natural antioxidants. However, the low antioxidant ability of sugarcane juice (EC50 = 100.2 ± 2.6 g L-1) also points to the need for further studies about the dietary intake of sugarcane flavonoids and its effects on human health.

Thermo-optical characteristics and concentration quenching effects in Nd(3+)doped yttrium calcium borate glasses

In this work we present a comprehensive study of the spectroscopic and thermo-optical properties of a set of samples with composition xNd(2)O(3)-(5-x)Y(2)O(3-)40CaO-55B(2)O(3) (0 <= x <= 1.0 mol%). Their fluorescence quantum efficiency (eta) values were determined using the thermal lens technique and the dependence on the ionic concentration was analyzed in terms of energy transfer processes, based on the Forster-Dexter model of multipolar ion-ion interactions. A maximum eta = 0.54 was found to be substantially higher than for yttrium aluminoborate crystals and glasses with comparable Nd(3+) content. As for the thermo-optical properties of yttrium calcium borate, they are comparable to other well-known laser glasses. The obtained energy transfer microparameters and the weak dependence of. on the Nd(3+) concentration with a high optimum Nd(3+) concentration put this system as a strong candidate for photonics applications. (C) 2011 American Institute of Physics. [doi:10.1063/1.3567091]

Polymer matrix sensitizing effect on photoluminescence properties of Eu(3+)-beta-diketonate complex doped into poly-beta-hydroxybutyrate (PHB) in film form

In this work is reported the sensitization effect by polymer matrices on the photoluminescence properties of diaquatris(thenoyltrifluoroacetonate)europium(III), [Eu(tta)(3)(H(2)O)(2)], doped into poly-beta-hydroxybutyrate (PHB) with doping percentage at 1, 3, 5, 7 and 10% (mass) in film form. TGA results indicated that the Eu(3+) complex precursor was immobilized in the polymer matrix by the interaction between the Eu(3+) complex and the oxygen atoms of the PHB polymer when the rare earth complex was incorporated in the polymeric host. The thermal behaviour of these luminescent systems is similar to that of the undoped polymer, however, the T(onset) temperature of decomposition decreases with increase of the complex doping concentration. The emission spectra of the Eu(3+) complex doped PHB films recorded at 298 K exhibited the five characteristic bands arising from the (5)D(0) -> (7)F(J) intraconfigurational transitions (J = 0-4). The fact that the quantum efficiencies eta of the doped film increased significantly revealed that the polymer matrix acts as an efficient co-sensitizer for Eu(3+) luminescent centres and therefore enhances the quantum efficiency of the emitter (5)D(0) level. The luminescence intensity decreases, however, with increasing precursor concentration in the doped polymer to greater than 5% where a saturation effect is observed at this specific doping percentage, indicating that changes in the polymeric matrix improve the absorption property of the film, consequently quenching the luminescent effect.