Resumo em Inglês:

A new method has been developed to determine trace levels of organophosphorus pesticide parathion-methyl in water samples by using dispersive liquid-liquid microextraction (DLLME), followed by gas chromatograph coupled with electron capture detector (GC/ECD) analysis. The optimized and validated method showed high extraction recovery (101.1%), high enrichment factor (57.3), low limits of detection and quantification, 0.083 and 0.250 µg L-1, respectively. The established DLLME-GC/ECD method has been successfully applied for the evaluation of the photodegradation of the parathion-methyl by UV254nm radiation in different conditions of pH and temperature. The parathion-methyl photodegradation at pH 3 and 35 °C achieved > 99.5% after 120 min of exposition. For this condition, it was observed the kinetic rate of 0.0515 min-1, the quantum yield of 1.22 × 10-5 mol Einstein-1 and a half-life time of 13.46 min. All experimental conditions tested proved to be strongly influenced by pH and temperature. The application of the optimized process in distilled and drinking water spiked with parathion-methyl provided residues of this pesticide at levels below the maximum permitted by Brazilian legislation, which is 9.0 µg L-1.

Resumo em Inglês:

A new series of benzazole, thiazolidinone and azetidin-2-one derivatives incorporating to pyrazole moiety were synthesized by condensation of 1,3-diphenyl-1H-pyrazol-4-carboxaldehyde with different nucleophiles. The structures of the newly synthesized compounds were confirmed by analytical and spectral methods. Some of these compounds were evaluated for their anti-hyperglycemic and renoprotective activities. Three compounds showed remarkable anti-diabetic potency, whereas other five compounds showed significant renoprotective activity.

Resumo em Inglês:

This work shows the modification of microcrystalline cellulose by the selective oxidation of primary hydroxyl groups to carboxylate groups by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated system and its application as a heterogeneous ligand by ionic exchange with catalytic metals ions such as palladium, nickel and copper. Afterwards is described the application of the synthesized material as catalyst in coupling reactions such as Suzuki-Miyaura coupling and C−O bond formation reaction in different conditions, which are of great importance for the synthesis of drugs, natural products and new materials such as dendrimers, liquid crystals and polymers with magnetic and optical properties. The carboxyl cellulose matrix shows to have superior catalytic results as a ligand for all coupling reactions. Can be also highlighted the affinity of the carboxyl cellulose ligand in polar solvents such as water and alcohols and its application in mild conditions.

Resumo em Inglês:

A same coordination polymer [Zn(aip)(DMSO)] (aip: 5-aminoisophthalate and DMSO: dimethylsulfoxide) was synthesized using the same reactants (ZnSO4, aip and H2O/DMSO) but in different conditions, in which the stoichiometry (1:1-4:1 metal:ligand ratio), temperature (70 and 100 °C) and synthetic method (liquid-liquid diffusion, solvothermal and conventional with stirring) varied. A liquid assisted mechanochemical approach using ZnO as ZnII source instead ZnSO4, but keeping DMSO as milling liquid, also resulted in the same compound. This new coordination polymer was investigated using single-crystal X-ray diffraction technique, revealing a two-dimensional honeycomb-type network formation. The crystal structure was compared with either similar or isostructural compounds reported in the literature. Our studies show that the synthetic method and other synthetic variables do not affect the formation of [Zn(aip)(DMSO)] coordination polymers and probe the high stability (thermodynamic and kinetic) and structural invariance of this structure.

Resumo em Inglês:

The present work investigates the use of W/WO3 electrodes prepared by electrochemical anodization applied in the photoelectrocatalytic disinfection of Candida parapsilosis using ultraviolet-visible (UV-Vis) and visible irradiation. The core objective of this work lies in describing a novel approach involving the use of chloride as supporting electrolyte, aiming at achieving a faster inactivation and towards understanding its behavior in water containing high chloride content. The best experimental conditions were found to be at pH 7.0 and 0.1 mol L-1 NaCl when the photoelectrode was biased at 1.5 V (vs. Ag/AgCl) illuminated by both UV-Vis and visible light. It is suggested that charges photogenerated on the electrode surface give rise preferably to HO•, known to be powerful oxidant that causes the total inactivation of the microorganism (1 min of treatment) while engendering around 84% of mineralization of organic matter released from the cell damage following 120 min of treatment.

Resumo em Inglês:

A fast, simple and inexpensive procedure is described for the determination of gossypol in cottonseed meal. The procedure is based on a flow injection analysis system and a complexation reaction with spectrophotometric detection at 620 nm. A fluidized bed column was used to implement the on line that was coupled to the extraction flow system in order to analyze the solid samples directly. A linear response was observed from 0.96 to 3.85 mmol L-1, and the detection limit, the coefficient of variation and the sampling rate were estimated at 100 µmol L-1 (99.7% confidence level), 1.90% (n = 20) and 30 h-1, respectively. The reagent consumption was 1.08 mg of Fe(NO3)3, with a volume of 20 mL of effluent per determination. Analyses of the results of commercial samples were consistent with through the official procedure of detoxification of cottonseed meal as described by American Oil Chemists’ Society (AOCS) at the 95% confidence level.

Resumo em Inglês:

Heterocyclic oxime ethers play a significant role in organisms due to their biological activity. Lipophilicity is an important parameter that may affect biological activity of the compounds 1-(benzofuran-2-yl)ethan-1-one oxime and its nine biologically active ethers. The relationship between the structure and lipophilicity parameters (log kw values) of the ten compounds is here described. Reversed phase high performance liquid chromatography (RP-HPLC) method was used having methanol, 2-propanol and acetonitrile as organic modifiers of the mobile phases. Both experimental (log kw) and calculated (log P) parameters showed to be strongly positively correlated. The weakest correlation with all the data was for the log kw methanol. For all of analyzed compounds, log kw values are smaller than 5 (except for analyses carried out in methanol), and this result corresponds to the Lipinski’s rule in the range of lipophilicity. Therefore, in the case of their use as drugs, they will be probably active after oral application.

Resumo em Inglês:

The synthesis of 5-[2-(trifluoromethylheteroaryl)-ethyl]-1,3,4-oxadiazoles derived from levulinic acid is reported. Cyclocondensations [4 + 1] between four different 5-[2-(trifluoromethylheteroaryl)propionylhydrazides derived from methyl 7,7,7-trifluoro-4-methoxy-6-oxo-4-heptenoate obtained from levulinic acid, and electrophilic orthoesters RC(OR1)3 (where R = H, Me, Ph) and CS2 were carried out in a mild medium. Good yields (69-96%) of isolated products were obtained. The structures of the new ethylene-spaced biheterocycles were characterized using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization coupled to tandem mass spectrometric (ESI MS/MS) data.

Resumo em Inglês:

The cis-[Ru(bpy)2(4-bzpy)(NO)](PF6)3 complex was prepared (4-bzpy = 4-benzoylpyridine), and characterized by UV-visible, infrared and nuclear magnetic resonance (NMR) spectroscopies and electrochemical techniques. The reaction with cysteine was preliminarily investigated, aiming to shed light on the potential biological mechanism for NO or HNO release mediated by thiols. Furthermore, photochemical behavior of cis-[Ru(bpy)2(4-bzpy)(NO)](PF6)3 was studied, where it was observed NO release upon ultraviolet, blue and green light irradiations. This latter long wavelength showed still good efficiency, which has not been reported for this type of complex. This feature is very important for a potential application in phototherapy. Additionally, vasorelaxant activity was investigated in rat-isolated aorta. This compound exhibited a greater maximum efficacy than sodium nitroprusside (SNP) as a blood vessel relaxant. Nevertheless, the EC50 for SNP (13.3 nmol L-1) was 52-fold smaller than the EC50 for cis-[Ru(bpy)2(4-bzpy)NO](PF6)3 (690 nmol L-1). Altogether, these results suggest this complex is a promising NO donor agent deserving further biological studies.

Resumo em Inglês:

In this paper we investigated the ability of the GIAO-mPW1PW91/6-31G(d)//mPW1PW91/6-31G(d) level of theory to predict the 13C nuclear magnetic resonance (NMR) chemical shifts of the 2’-hydroxy-3,4,5-trimethoxy-chalcone molecule. Two different approaches were used. First: the absolute shieldings σ for all carbon atoms in each geometrically optimized conformers of the 2’-hydroxy-3,4,5-trimethoxy-chalcone molecule were calculated at the GIAO-mPW1PW91/6-31G(d)//mPW1PW91/6-31G(d) level of theory. This approach is further used to generate weighted average values for each atom considering the previously obtained conformational distribution. Second: only the σ for the lowest energetic conformer will be taken to account. The robustness of the method was evaluated for two other chalcones: (E)-1-(4-hydroxy-3-methoxyphenyl)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)prop-2-en-1-one and (E)-1-(4-aminophenyl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one, corroborating the ability of the method in chemical shift prevision. Although, both approaches were able to reproduce the chemical shifts of the 2’-hydroxy-3,4,5-trimethoxy-chalcone, significant differences in the calculated values for C-4 and methoxy carbons were observed. The best results were obtained using the second approach (II).

Resumo em Inglês:

Perfumes are products mainly consisting of ethyl alcohol, water and fragrance. These fragrances are responsible for characterizing the pleasant and unique odor of each perfume. Among the fragrances, we highlight a group of fragrances which can cause contact allergy, leading to dermatitis. Brazilian and the European law state that when these concentrations of allergenic fragrances exceed the limit of 0.01% for non-rinse products and 0.001% for products with rinsing, the manufacturer is obliged to discriminate on its label their presence. This work aims to quantify allergic fragrances in original and Brazilian perfume using solid-phase microextraction and analyze by gas chromatography-mass detector.

Resumo em Inglês:

A multiresidue method was developed to estimate community drug use during two weekends of the 2014 Soccer World Cup via wastewater analyses. Five of the 16 investigated substances were detected in all eight samples. Benzoilecgonine (BE), the major cocaine metabolite, was the most abundant substance (1.9 ± 0.3 to 4.2 ± 0.2 μg L-1) followed by anhydroecgonine (AE) (1.5 ± 0.2 to 2.6 ± 0.2 μg L-1), phenacetin (PHE) (0.62 ± 0.06 to 1.3 ± 0.1 μg L-1), levamisole (LEV) (0.5 ± 0.2 to 1.23 ± 0.09 μg L-1), and cocaine (COC) (0.46 ± 0.07 to 0.8 ± 0.1 μg L-1). COC and BE levels suggested a human consumption origin for the investigated drugs. AE/BE ratios revealed a significant use of smoked crack/free base cocaine. Relationships between the adulterants PHE and LEV evidenced a higher use of crack cocaine in the South-Wing WWTP region. An estimative for cocaine use revealed slightly higher drug consumption during the Soccer World Cup weekends in comparison with a typical weekend in 2012.

Resumo em Inglês:

Natural α,β-amyrins were isolated from endemic Brazilian Esenbeckia grandiflora Mart., and eight synthetic derivatives were obtained by esterification reactions with bromo acetate, followed by amine treatment. The structures of the all compounds were confirmed by 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and high-resolution mass spectrometry (HRMS) data analysis. The derivatives were screened for cytotoxic activity against human tumor cell-lines PC3 (prostate carcinoma), HCT-116 (colon carcinoma) and HL60 (leukemia). HCT-116 and PC3 cell-lines showed weak tumor growth inhibition (range of 13.9-25.4 and 10.3-28.8%, respectively), but the derivatives presented moderate activity against HL60 (range of 13.6-59.0%). Diethyl, aniline, morpholine and imidazole moieties presented higher activities (range of 45.9-59.0%).

Resumo em Inglês:

In this study, inductively coupled plasma optical emission spectrometry (ICP OES) was used for multi-element analysis in five multimineral preparations from a dissolution test, in accordance with the United States Pharmacopeia (USP 34 method): apparatus 1, 75 rpm and 900 mL of 0.1 mol L-1 HCl. Element releases in all samples (minimum-maximum in %) were: Ca (14.5-28.2), Cr (54.5-68.0), Cu (2.9-10.0), Fe (4.0-34.3), Mg (6.0-25.2), Mn (2.6-51.2), V (0.0-51.4) and Zn (1.5-107.3). The concentrations of Al, Ba, Cd, Co, Mo, Pb and Se were below the limit of detection of ICP OES. Accuracy was assessed by microwave digestion and recovery values of 94-102%. USP 34 method indicates that not less than 75% of the elements described on the product label must be dissolved in 1 h. Only the release of Zn met the recommendations. The results indicated the need for greater quality control in multivitamin preparations. The dissolution test was validated in order to contribute to Brazilian and other pharmacopoeias.

Resumo em Inglês:

Suspension of picric acid (PA) loaded iron oxide nanoparticles (PA-IONPs) was injected on the top of a 0.2 µm HPLC (high-performance liquid chromatography) syringe filter. The immobilized nanoparticles were used as SPE (solid phase extraction) sorbent for perphenazine separation and pre-concentration. By passing perphenazine solution through the filter, a molecular complex between perphenazine and PA was formed. Perphenazine/PA complex was eluted from the filter using dichloromethane as solvent. The perphenazine contents were determined at 254 nm. Effects of the parameters such as pH, the amount of PA-IONPs, as well as flow rate, volume, and type of eluting solvents, on the separation efficiency and pre-concentration of perphenazine were investigated. The calibration curve was linear in the range of 0.5-5 ng mL-1 (Y = 0.047X + 0.018; R2 = 0.9952) with limit of detection of 0.16 ng mL-1. The pre-concentration and enrichment factors were 8.33 and 1.88, respectively. This method was successfully applied to the determination of perphenazine residue in tap water.

Resumo em Inglês:

The structures of two methoxylated chalcones, namely (E)-1-(4-methoxyphenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one and (E)-3-(4-ethoxyphenyl)-1-(4-methoxyphenyl)prop-2-en-1-one, reveal the effect of the inclusion of the methoxyl and ethoxyl substituents of the conformation on methoxy-chalcone. Structural comparative study between two chalcones was done in this work and some effects on geometric parameters, such as planarity and dihedral angles, were described. In addition, intermolecular interactions responsible for crystalline packaging were investigated by Hirshfeld surfaces and the values of those interactions were analysed by comparing experimental and theoretical models. The molecular stability was expressed in terms of softness and hardness, both obtained from frontier molecular orbitals. Finally, there is a good agreement between calculated and experimental infrared spectrum, which allowed the assignment of the normal vibrational modes.

Resumo em Inglês:

Carriers with different functional groups (epoxy, aldehyde, ethyldiazonium, phenyldiazonium and amino) were tested for immobilization of T. versicolor laccase on GMA-co-EGDMA (glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres. Laccase immobilized on GMA-co-EGDMA containing the phenyldiazonium functional group showed the highest activity (96.3 U g-1). The immobilized laccase was used for removal of bisphenol-A (BPA) from aqueous solution. The temperature effect was significant on activity, but insignificant on BPA removal by the immobilized laccase. In the temperature range 10-60 °C, the removal of BPA by laccase in the immobilized form was about four times higher than that in the free form. Swelling does not affect the activity of immobilized laccase, but after 8 cycles of 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) oxidation, non-swollen immobilized laccase was able to retain 71% of the starting activity while the 24 h swollen kept 61%. At neutral pH, adsorption onto the immobilized laccase accounted for 92% of the BPA removed while enzymatic conversion accounted for 8%. However, when increasing the pH to 10, the fraction of BPA removed by adsorption decreased to 67% and by enzymatic conversion increased to 33%.

Resumo em Inglês:

The biofuel properties of biomass play an important role in achieving their utilization on agro-systems and industries. In this context the biomass waste of maize, corncob husk, and its biochars were taken into account to be investigated by thermogravimetric analysis, thermodynamic parameters for non-isothermal analyses using the Ozawa-Flynn-Wall kinetic isoconversional model in order to comprehend its possible fuels features. It was also investigated the compounds generated after pyrolysis and their relation with oxidation reactions for the safe-handling and storage. It was found that corncob husk biochar produced at 300 °C shows the best qualities as a solid biofuel, since it requires less energy input through pyrolysis to be produced. Finally, analysing the compounds generated and remained on the biochar’s surface, by Fourier transform infrared spectroscopy (FTIR) analysis, biochars produced at low temperatures present one of the lowest features prone to oxidation reactions.

Resumo em Inglês:

Rice husk ash (RHA) is a waste material produced in large quantities in many regions worldwide, and its disposal can be problematic. This work describes a method for using RHA to synthesize silicon and potassium slow-release fertilizer. The extraction of silica from RHA was accomplished by alkaline leaching with KOH. Different KOH concentrations and reaction times were evaluated and the best production of K2SiO3 solution was achieved using 6 mol L-1 and 6 h, respectively. The fertilizer was synthesized by the reaction of K2SiO3 with KAlO2 in aqueous medium, followed by calcination at 500 °C. X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses indicated that the fertilizer composition was similar to mineral kalsilite. Solubility essays indicated lower K+ and Si4+ release percentage in neutral medium. Kinetic mechanisms of release tests can be well explained by the pseudo-second order model. The proposed synthesis seems to be a viable process offering economic and environmental benefits.

Resumo em Inglês:

Cholinesterase enzymes are important targets for the therapy of Alzheimer’s disease. Tacrine-based dual binding site cholinesterases inhibitors are potential disease-modifying anti-Alzheimer drug candidates. In the present work, we described the synthesis of a series of chiral homo- and heterodimers of bis(7)-tacrine connected by a heptylene chain as a spacer with the methyl substituent at the C-3 position of the alicyclic region of tacrine nucleus and/or a chlorine atom attached to the C-6. Friedländer cyclocondensation between (R) or (S) 3-methylcyclohexanone prepared from monoterpene pulegone and o-aminobenzoic acids in the presence of POCl3 afford 9-chloroacridines as intermediates, which were used to the synthesis of homo- and heterodimers. All compounds demonstrated to be potent inhibitors of acetylcholinesterase (AChE) at low nanomolar concentration and showed selectivity for AChE over butyrylcholinesterase (BuChE). Furthermore, the affinity difference between enantiomeric bis(7)-tacrine analogues series indicated some degree of stereoselectivity in the active site of AChE for chiral bis-cognitin compounds.

Resumo em Inglês:

Neolignans are a class of natural products with a wide range of biological effects. These substances are of great synthetic and biological interest, especially in searching for novel anticancer agents. In this paper, we report the synthesis of a new subclass of 8,4’-oxyneolignan analogues (β-ketoethers and β-ketoesters) and their cell viability assay on twenty four different cancer cells, among leukemias and carcinomas. Three compounds inhibited the growth of most human cancer cells. 2-Oxo-2-phenylethyl(2E)-3-[4-(2-oxo-2-phenylethoxy) phenyl]prop-2-enoate showed an antiproliferative activity superior to doxorubicin for U-87, U-138 MG and H1299 cell types and (E)-2-oxo-2-phenylethyl 3-(3-methoxy-4-(2-oxo-2-phenylethoxy)phenyl)acrylate was found to be very selective, demonstrating a growth inhibition of 92.0% against KG-1 cells. Furthermore, 1-oxo-1-phenylpropan-2-yl cinnamate exhibited significant inhibition activity in a range of 52.2 to 91.2% against twelve kinds of leukemia cell lines, revealing excellent results and very comparable to the reference drug.

Resumo em Inglês:

A synthetic niobia was modified by treatment with hydrogen peroxide to be used as a catalyst for converting glycerol into petrochemical compounds. The catalytic properties of niobium oxyhydroxide were obtained by generating acidic and oxygenated groups (peroxo groups) on the solid surface. Compounds like ethers and allyl alcohol were obtained. A very active H2O2-modified catalyst showed high activity for the oxidation and dehydration of 91% of glycerol conversion using H2O2 and 46% of allyl alcohol selectivity in volatile phase. The product was analyzed by gas chromatography-mass spectrometry (GC-MS), thermogravimetry-mass spectrometry (TGA-MS) and nuclear magnetic ressonance (NMR). These results strongly suggest that the reactions involve acid and oxidizing species generated after the reaction of niobium with H2O2. 1H and 13C multidimensional NMR spectroscopy confirmed the results obtained with GC-MS and showed the production of several compounds after niobia treatment.

Resumo em Inglês:

Lithium cobalt oxide, LiCoO2, widely used as cathode in lithium ion batteries was synthesized and their structural and electronic properties investigated. The crystalline powders were prepared by the sol-gel method with four complexing agents: citric acid, glycine, starch and gelatin. These syntheses were compared with the blank test (without complexing agent). The X-ray diffraction and vibrational spectroscopy allowed the identification of the rhombohedral phase LiCoO2 (R3m) as the only or principal crystalline component in all samples. A small fraction of a second phase of cubic spinel Co3O4 was observed in the samples of starch, gelatin and the blank test. The Rietveld refinements showed small structural variations, indicating reduced influence of the complexing agents on the synthesis. The theoretical HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gap values are in agreement to those estimated by diffuse reflectance spectroscopy (DRS). The scanning electron microscopy (SEM) showed morphological pattern regardless of the complexing agent used, showing an alternative method.

Resumo em Inglês:

The rate coefficient of the cis-3-hexene + Cl atoms reaction at 296 ± 2 K and 750 ± 10 Torr was determined using the relative rate technique. The reaction was investigated using an 80 L Teflon reaction bag and a gas chromatograph coupled with flame-ionization detection. Chlorine atoms were produced by the photolysis of trichloroacetyl chloride. No previous experimental data was available in the literature, to the best of our knowledge. The mean second-order rate coefficient value found was (4.13 ± 0.51) × 10-10 cm3 molecule-1 s-1. The experimental value agrees with the rate coefficient estimated by structure-reactivity analysis, 4.27 × 10-10 cm3 molecule-1 s-1. Moreover, both addition and hydrogen abstraction channels contribute to the global kinetics, with branching ratios 70:30. Effective lifetime with respect to Cl atoms is predicted as 67.2 hours; however, the cis-3-hexene + Cl channel is suggested to be non-negligible at atmospheric conditions. Other atmospheric implications are discussed.

Resumo em Inglês:

A new pyranone, (S)-2-(4-hydroxyphenylethyl)-6-methyl-2,3-dihydro-4H-pyran-4-one, with unusual carbon skeleton, and three new aristolochic acid derivatives (7-O-methylaristolochic acid F, sodium 7-O-methylaristolochate F and sodium aristolochate F) were isolated from Aristolochia urupaensis (Aristolochiaceae) stems together with 31 known compounds. The structures of the compounds were determined by spectroscopic analyses, including Fourier transform infrared (FTIR) and 1D and 2D nuclear magnetic resonance (NMR) techniques, and high-resolution mass spectrometry (HRMS).