Resumo em Inglês:

Two novel proton transfer compounds (HAP)+(SAMAL)- and (HBI)+(SAMAL)-.H2O were obtained from (E)-4-oxo-4-(4-sulfamoylphenylamino)but-2-enoic acid (HSAMAL) and 2-aminopyridine (AP) or 1H-benzimidazole (BI), respectively. Copper(II) complexes of salts and of HSAMAL have also been prepared. They have been characterized by elemental, spectral, thermal analyses, magnetic measurement and molar conductivity. Human carbonic anhydrase isozymes (hCA I and hCA II) were purified from erythrocytes by using affinity chromatography as 84.40 and 188.71 fold, respectively. The inhibitory effects of synthesized compounds and acetazolamide (AAZ, control compound) on the hydratase and esterase activities of hCA isozymes have been studied as in vitro to find out their antiglaucoma potentials. The inhibition constant (Ki) values of the compounds were in the range of 0.18 ± 0.007 to 10.24 ± 0.014 µmol L-1 for hCA I, and 0.12 ± 0.004 to 130.11 ± 0.021 µmol L-1 for hCA II.

Resumo em Inglês:

Carbon black (CB) grafted with 3-mercaptopropyltrimethoxysilane (3-MPTMS) was used as solid phase extractor for Cd2+ in a flow injection system coupled to flame atomic absorption spectrometry (FAAS). The influence of pH, buffer concentration, preconcentration flow rate and eluent concentration on preconcentration of Cd2+ were investigated by means of chemometric tools. The characterization of the adsorbent chemically modified was performed by Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis, Raman spectroscopy and textural analysis. To perform the on-line preconcentration, 20.0 mL of a pH 7.0 Cd2+ solution at a flow rate of 4.0 mL min−1 was loaded through 30.0 mg of modified CB and then eluted with 1.0 mol L−1 HCl toward the FAAS instrument. The limits of detection and quantification were found to be 0.20 and 0.66 µg L−1, respectively. Addition and recovery tests carried out in real samples (mineral, tap and saline waters, and cigarette sample) and the analysis of certified reference material (TORT-2, lobster hepatopancreas reference) attested the applicability of proposed method.

Resumo em Inglês:

This study aimed to evaluate the effect of strobilurin (pyraclostrobin) + triazole (epoxiconazole) fungicides application on the proximate composition of soybeans. Six treatments of varying numbers of fungicide applications following soybean germination, termed T1 (control), T2, T3, T4, T5, and T6, were assessed for this experiment. Based on the results, there were only minor differences in the proximate composition of soybeans in terms of moisture, ash, crude protein, and total lipid contents. In contrast, there were large effects on the contents of phenolic compounds and the levels of phytosterols and tocopherols, which varied greatly among the fungicide application treatments. Multivariate statistical analysis was applied to identify critical issues regarding the potential for the production of soybeans enriched in phenolic compounds, tocopherols, and essential fatty acids (α-linolenic and linoleic acids, representatives of the omega-3 and omega-6 families, respectively) associated with the number of sprayings applied during the development of soybean crops.

Resumo em Inglês:

Twelve Cirsium sp. methanolic extracts were analyzed using high-performance liquid chromatography gradient elution method with run time of 45 min. Four Kinetex (150 × 4.6 mm) chromatographic columns (C18 5 µm, C18 2.6 µm, pentafluorophenyl 5 µm, phenyl-hexyl 5 µm) and mobile phase consisting of methanol/water/formic acid 1% were used. Eight standards (naringin, vanilic acid, chlorogenic acid, caffeic acid, rutin, luteolin, apigenin, p-coumaric acid) were analyzed in the same conditions to confirm their presence in all of Cirsium methanolic extracts. The obtained chromatograms were compared and the similarity between them was evaluated using the similarity indices (Pearson's correlation coefficient, determination coefficient and congruence coefficient), distance indices (Euclidean, Manhattan and Chebyshev distance) and multi-scale structural similarity (MS-SSIM). Obtained results were confirmed using the principal component analysis (PCA). The attempt of identification of two unknown Cirsium species was performed using the similarity, distance indices and PCA analysis.

Resumo em Inglês:

The use of thin-film microextraction for the extraction of selected pharmaceutical compounds followed by gas chromatography-mass spectrometry detection was evaluated. A segment of polysiloxanes polymer sheet was used as low cost, single use, disposable extraction phase, while Milli-Q water spiked at 20 µg L−1 with the analytes was used for the optimization assays. The controlling parameters for the extraction were optimized via experimental design and it was found that an extraction time of 3 h using a sample volume of 1000 mL at pH 4 with the addition of 20% methanol and 20% sodium chloride provided the greatest extraction efficiency. Recoveries between 67.1 and 85.0% were achieved, with a repeteability lower than 20% (expressed as coefficient of variation) and limit of detection ranged from 0.41 and 0.92 µg L−1. The proposed method show similar analytical performance when compared to the determination of the analytes using stir bar sorptive extraction.

Resumo em Inglês:

The goals were to estimate nutrients and carbon flow rates between Guanabara Bay and the adjacent coastal waters, to characterize the provenance of the exported/imported organic matter. Samples were collected from different depths over 25 h in two seasons at the bay entrance. Measurements included physicochemical parameters, nutrients, chlorophylls, dissolved organic carbon (DOC), particulate organic carbon (POC), particulate nitrogen (PN), carbon (δ13C) and nitrogen (δ15N) isotopic composition, sterols in suspended particulate matter (SPM) and bacterioplankton. Most variables showed higher values in ebb tide events. The flow rates calculated on daily basis and estimated on annual basis revealed the exportation to the continental shelf of 1.27 × 104 kmol year-1 dissolved inorganic nitrogen (DIN), 9.52 × 102 kmol year-1 dissolved inorganic phosphorus (DIP), 2.65 × 104 t year-1 DOC, 1.96 × 104 t year-1 POC, and 2.96 × 104 t year-1 PN. The estimates show the bay contributes with 0.01% of the total global carbon influx to the ocean.

Resumo em Inglês:

The surface of nano titania was phosphate modified and characterized by X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), energy dispersive X-ray analysis (EDX), and elemental analysis (CHN) to show the existence of phosphate in the modified nano titania. The resultant phosphated nano titania was applied for photocatalytic degradation of ethylenediaminetetraacetic acid disodium salt (EDTA) in aqueous solution. The crystallite size and crystalline phase showed no considerable change after modification, hence photocatalytic effect improvement of phosphate modified nano titania compared with the pure nano titania could be probably due to the existence of phosphate groups on the surface. The changes of the initial pH, photocatalyst dosage and EDTA concentration were tested in the degradation experiments. The pseudo-first-order kinetic model described the dynamic behavior for the photocatalytic degradation of EDTA using phosphate modified nano titania.

Resumo em Inglês:

Herbicidal ionic liquids exhibit many advantages compared to conventional chemical plant protection agents, which allow for a reduction of the herbicide dose per hectare and decrease of toxicity. Popular herbicides, such as 4-chloro-2-methylphenoxyacetic (MCPA) or 2,4-dichlorophenoxyacetic (2,4-D) acids, can be modified by reaction with long chain ammonium cations in order to obtain novel forms. The aim of this study was to present an alternative method for the synthesis of herbicidal ionic liquids based on a natural cation known as Ethoquad C/12 and to analyze the physicochemical properties and herbicidal activity of the obtained products. New ionic liquids comprising MCPA and 2,4-D as anions were obtained and their chemical as well as thermal stability were evaluated. Furthermore, their biological and surface activity were investigated. The obtained results confirmed that the herbicidal activity has been preserved.

Resumo em Inglês:

A gas chromatography tandem mass spectrometry has been developed and validated for the separation, detection, identification and quantification of acrylamide in bread, biscuits and similar products. The method showed good precision with values lower than 6%. A good sensitivity was achieved for bread with 2.41 and 7.23 µg kg-1 limit of detection (LOD) and limit of quantification (LOQ), respectively, while for biscuits, LOD and LOQ were 4.63 and 13.89 µg kg-1, respectively. Accuracy obtained through the bias of 2 certified reference materials ("crisp bread - ERM®-BD272" and "rusk - ERM®-BD274") gave a value below 1.68-2.52%. The method was applied by analyzing 49 types of bread, biscuits and other similar products. The results showed different levels of acrylamide in bread (values ranged between 7.6 and 165.6 µg kg-1), biscuits (between LOD and 2405.0 µg kg-1), sandwich biscuits with cream (112.6-570.4 µg kg-1), biscuits for infants and young children (between LOD and 801.7 µg kg-1), gingerbread (349.5-955.5 µg kg-1) and crackers (347.8-366.1 µg kg-1).

Resumo em Inglês:

A method for simultaneous determination of nine sulfonylurea herbicides in water and soil samples with solvent demulsification-dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with high perfomence liquid chromatography was established. 120 µL of 1-dodecanol as extractant and 400 µL of methanol as dispersing reagent were injected into the sample solution adjusted to pH 2.0 to extract the target compounds for high performance liquid chromatography (HPLC) analysis. The detection limits were 0.24-0.81 µg L-1 for water samples and 2.42-8.12 µg kg-1 for soil samples, and the quantification limits were 0.79-2.69 µg L-1 for water samples and 8.06-27.04 µg kg-1 for soil samples respectively. The average recoveries were 78.9-104.8% with the relative standard derivations (RSDs) of 2.73-10.4% for water samples, and 75.5-107% with the RSDs of 5.66-12.4% for soil samples. The method had the advantages of little consumption of organic solvent, low cost and high enrichment factors.

Resumo em Inglês:

The role of the "tape tea" as a low cost abuse drug is evaluated, by searching for possible inorganic and organic compounds after its preparation. Two energy sources are evaluated (conventional and microwave heating) for preparing the "tape tea" using new or used cassette (K7) or video home system (VHS) tapes. After optimizing all the inductively coupled plasma mass spectrometry (ICP-MS) conditions, the remarkable presence of Mn and Co, as well as Cr and Ni, at concentrations higher than 5 times those allowed for drinking water, makes the use of the "tape tea" plausible as a non-cost abuse drug due to some possible neurotoxic effects. Regarding the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) analysis, no evidence of any organic compound related to neurological effects was found.

Resumo em Inglês:

A series of ten new compounds have been synthetized in satisfactory yields (85-95%) through the treatment of isopropyl mesoionic 1,3-thiazolium-5-thiolate with 2-chloro-N-arylacetamides and characterized by elemental analysis, infrared (IR), 1H and 13C nuclear magnetic resonance (NMR) spectroscopies. The newly synthesized compounds were evaluated as new drug candidates in in silico study and for their antifungal activity against several strains of Candida albicans. In silico study indicates that no compound has potential to be a new drug while four compounds showed medium to strong activity with minimum inhibitory concentration (MIC) range of 256-1024 µg mL-1.

Resumo em Inglês:

Solid-phase peptide synthesis of dipeptide (histidine-β-alanine) as a chelating agent examined by common N-9-fluorenylmethyloxycarbonyl-N-trityl-L-histidine and tert-butyloxycarbonyl-β-alanine-OH amino acid derivatives. Trityl chloride resin was used as a carrier resin. The molecular structure of the dipeptide was definite by using different methods such as ultraviolet visible (UV-Vis), Fourier transform infrared (FTIR), proton (1H) nuclear magnetic ressonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) and the chelating property of synthesized dipeptide was investigated for removing of metal ions Al3+, Cu2+, Hg2+ and Pb2+in vitro. In addition, the pharmacological and biological activities of dipeptide were examined by prediction of activity spectra for substances (PASS) program.

Resumo em Inglês:

The synthesis of oxygen- and nitrogen-substituted indanes was successfully performed by iodine(III)-mediated ring contraction of 1,2-dihydronaphthalenes. Acetoxy and benzoyloxy alkenes afforded indanes in 60-71% yield, irrespective of their position on aromatic ring. Similarly, the nitrogen containing substrates protected with 9-fluorenylmethyloxycarbonyl (Fmoc) and benzoyl (Bz) groups smoothly undergoes ring contraction giving indanes in 64-77% yield. The tosyl-protected substrate resulted only in addition products.

Resumo em Inglês:

A continuous-flow process at atmospheric pressure was designed for the conversion of glycerol to solketal, an oxygenated fuel additive, through the acid-catalyzed reaction of glycerol with acetone. Process optimization was performed by checking the influence of different variables on the conversion and selectivity. The variables examined were: residence time (12, 24, 60 and 120 min), catalyst type (Amberlyst-15 and K-10 Montmorillonite), catalyst loading (7, 3, and 1 g), reaction temperature (50, 40 and 30 ºC), molar ratio of the reactants (1:2, 1:5, 1:10, 1:15 and 1:20) and solvent used to homogenize the system (dimethylsulfoxide or dimethylformamide). The highest conversion (92%) was observed with 7.0 g of Amberlyst-15, reaction temperature of 50 °C, molar ratio of glycerol to acetone of 1:20 and dimethylformamide as solvent. In all cases, solketal isomers (five and six-membered ring ketals) were the only product observed. The results of solketal formation of this study, carried out at atmospheric pressure, were similar to other studies with pressures of up to 120 bar. The utilization of higher catalyst loading and molar ratio of reactants compensate the use of atmospheric pressure to achieve high conversion levels and selectivity to the desired product

Resumo em Inglês:

Due to the economic potential of camu-camu, considering its high concentration of vitamin C, the aim of this work was to evaluate the quality and genetic variability seven accessions of camu-camu conserved in genebank (BAG) of Embrapa Amazônia Oriental, in the state of Pará, Amazon region, Brazil. The fruits of camucamuzeiro were analyzed for physicochemical characterization (standard methodologies) and mineral composition. The data were subjected to multivariate statistical analysis, using the techniques of cluster analysis and principal component analysis. The formation of different groups for each genotype, which shows the genetic variability and the dissimilarity of the genotypes in the species data, may be used to guide the selection of promising genotypes to enrich the programs of genetic improvement of the camucamuzeiro. Ascorbic acid showed levels above 1000 mg 100 g-1, however, genotypes 4, 1 and 2 show the highest potential and the most promising nutritional capacity, but genotype 4 showed good characteristics for the moisture, acidity, carbohydrates, Cu and Zn and differs totally from others about the total soluble solids (TSS) and flavon-3-ol, features that make it the most promising genotype. It was possible to separate the seven different genotypes using multivariate analysis (hierarchical cluster analysis-HCA and principal component analysis-PCA).

Resumo em Inglês:

Hybrid materials based on polyaniline (PAni) were obtained by in situ polymerization of aniline with chitosan and/or organically modified clay (nanomer I-24) in HCl. The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and direct current (DC) electrical conductivity. Thin films of PAni, PAni-clay, PAni-chitosan and PAni-chitosan-clay were prepared by casting a solution of each sample in N-methyl-2-pyrrolidone (NMP) onto indium tin oxide (ITO)/glass electrodes and their electrochromic properties were investigated. It was observed color variation from transparent yellow in the reduced state (E = -0.2 V vs. Ag/AgCl), green in the intermediate state (E = 0.5 V) and dark blue in the oxidized state (E = 0.8 V) for all samples. The color changes of each material in function of the applied potential were tracked using the Commission Internationale de l'Eclairage (CIE) system of colorimetry, in which the color change was much more significant for PAni-clay film.

Resumo em Inglês:

The interaction between 19-nor-clerodane trans-dehydrocrotonin (from Croton cajucara Benth.) and bovine serum albumin was studied, applying spectroscopic techniques (fluorescence and circular dichroism), combined with molecular modeling. Fluorescence quenching of albumin by the nor-clerodane (kq ca. 1011 mol L-1 s-1 and Stern-Volmer, KSV, increase with temperature) indicates a combination of static and dynamic quenching mechanism. The binding constant (Kb ca. 103 mol L-1) and circular dichroism data suggest that this association is weak and causes only a moderate change in the α-helix content of the protein. Thermodynamic parameters indicate a spontaneous (Gibbs free energy, ΔGº, ca. -21.28 kJ mol-1 at 310 K) and probably entropy-driven (ΔSº = 0.072 kJ mol-1 K-1) association, typical of hydrophobic interactions. The number of binding sites (n ca. 1) indicates one main binding site and molecular modeling suggests subdomain IIIA (Sudlow's site II) as the main binding site to the nor-clerodane, which is able to make hydrophobic interactions with leucine (Leu)-24, phenylalanine (Phe)-36, valine (Val)-40 and tryptophan (Trp)-134 residues.

Resumo em Inglês:

The additive substituent effect of phenylmercapto derivatives of corannulene are investigated by spectroscopic, electrochemical, and computational techniques. The per-substituted phenylmercaptocorannulene is incorporated as a replacement for [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in a photovoltaic device.

Resumo em Inglês:

Methanolic, diethyl ether and n-hexane extracts of leaves of four species of Senna (S. gardneri, S. macranthera, S. splendida and S. trachypus) were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Using linear retention indices and mass spectral data, 34 compounds were identified, including fatty acids, flavonoids, terpenoids and steroids that were not reported previously for these species. Additionally, the cytotoxicity of the extracts against different tumor cell lines was determined. The cytotoxicity was then correlated with the chemical composition of the extracts by partial least squares-discriminant analysis (PLS-DA). The n-hexane extract of S. gardneri and the ethyl ether extract of S. splendida were the most active against human colon (59.75 and 31.37%, respectively) and human glioblastoma (52.85 and 48.28%, respectively) cell lines.

Resumo em Inglês:

An on-line solid phase extraction (SPE) method using mini column packed with natural sorbent based on cotton roll dyed by quinalizarin was developed for simultaneously pre-concentration of rare earth elements and uranium at trace levels in environmental samples followed by inductively coupled plasma optical emission spectrometry (ICP OES) determination. Various parameters such as sample and eluent flow rate, sample volume and matrix ions on the method efficiency have been investigated. Under the optimized conditions, the limits of detection (LODs, 3σ) for rare earth elements were in the range of 0.002-0.300 µg L-1 and 0.420 µg L-1 for uranium. The relative standard deviation (n = 5) were lower than 6% except for samarium and uranium. The method was successfully applied for determination of trace rare earth elements and uranium in lake, well, tap water and carbonate mineral samples. The accuracy of the proposed method was validated by add-found method and direct analysis by ICP OES. This method has some advantages such as simplicity, rapidity, green chemistry and high sensitivity.

Resumo em Inglês:

The steam explosion was carried out in the absence (autohydrolysis) and presence of phosphoric acid to evaluate the effects of temperature (180 and 210 °C), acid concentration (0 and 19 mg g-1, dry basis) and pretreatment time (5 and 10 min) on the structure and reactivity of sugarcane bagasse. Glucan recovery was used as the main response factor for pretreatment optimization through a central composite design. Autohydrolysis at 210 °C for 10 min had a good pretreatment performance but phosphoric acid catalysis (19 mg g-1) resulted in better yields under considerably milder conditions (180 °C, 5 min). Hydrolysis of both substrates for 96 h using 8 wt.% total solids and 30 mg g-1 Cellic® CTec2 (Novozymes) provided total glucose yields of 75% in average. The production of cellulosic ethanol was assessed by both separate and simultaneous hydrolysis and fermentation using Saccharomyces cerevisiae. Freeze-drying of pretreatment water solubles reduced the concentration of furfural, hydroxymethylfurfural and acetic acid by more than 80% and this eliminated their inhibitory effect on yeast fermentation.

Resumo em Inglês:

This paper describes the development, evaluation, features and applications of Chromophoreasy, an alternative Excel-based program for recognition and integration of chromatographic and electrophoretic peaks. The proposed recognition is made according to parameters adjustable by the analyst, such as time range, noise smoothing window size and slope/curvature sensitivity. During integration, retention/migration time, area, height, half-height width, plate numbers, asymmetry factor, US Pharmacopeia tailing factor, resolution and statistical moments are determined. A chromatogram/electropherogram is plotted along with the found baselines. The effect of peak shape (heights and symmetries) and baseline slope over accuracy was evaluated and the precision of recognition/integration was investigated under several simulated conditions, with varied signal-to-noise levels, smoothing modes and smoothing window sizes. Data from liquid and gas chromatography, capillary electrophoresis and electrochromatography techniques with refractive index, flame ionization, capacitively coupled contactless conductivity (lab-made) and ultraviolet absorbance detections, respectively, were treated, illustrating the broad applicability of the proposed program for standard and sample analysis. Statistically similar results were obtained, when compared with other commercial software, showing it to be a simple, practical and reliable tool for general use in the separation area.

Resumo em Inglês:

In this work the vitamin C was determined in industrialized nectar juices through ultraviolet (UV) spectroscopy and multiproduct multivariate calibration, based on partial least squares (PLS) regression. Since samples with different flavors, sugar content (light or not) were together in the model construction, it can be considered as a multiproduct and, due to the heterogeneity of the samples, it was necessary to optimize the calibration and validation sets by outliers elimination. The model was developed and validated by the evaluation of the figures of merit such as: accuracy, sensitivity, analytical sensitivity, adjust, linearity, relative prediction deviation, limits of detection and quantification, indicating that the multiproduct model developed from UV spectroscopy and PLS regression can be used in the industrial routine analysis as an alternative to titration or other time and reagent consuming methods. Here, it was evidenced that the UV-PLS multiproduct model provides advantages as being free of sample preparation steps, is suitable to be updated in order to measure other parameters, does not generates residues and is feasible to be implemented for on-line monitoring. Furthermore, the application of multivariate calibration in multiproduct models is extremely attractive from the industrial point of view.

Resumo em Inglês:

In this work, we demonstrate a nuclear magnetic resonance (NMR) method for racemic amide and lipase interaction as a first-pass design method in the enzymatic kinetic resolution of amines. As a novel adaptation of commonly used protein-ligand screening NMR methodologies, this approach relies upon a lipase-amide interaction wherein the time-consuming is reduced drastically and new insights are produced during the development of biocatalysis reactions.