Resumo em Inglês:

Maytenus ilicifolia (Celastraceae) is a medicinal plant that is native to southern Brazil and is popularly known as “espinheira-santa”. From a biosynthesis perspective, this species accumulates quinonemethide triterpenes and sesquiterpene pyridine alkaloids as major secondary metabolites that exhibit interesting biological properties, with antitumoral and antiprotozoal activities, respectively, being the most frequently reported. Additionally, the restricted accumulation of such compounds in the roots raises questions about the expression of proteins involved in such compartmentalization and their possible biological and/or ecological role in M. ilicifolia. Thus, this article describes the use of shotgun proteomics and histochemical studies for the characterization of the main biosynthetic pathways involved in the regulation of the metabolism in M. ilicifolia roots. This combined approaches also resulted in the identification of a series of proteins involved in the quinonemethide triterpenes and sesquiterpene pyridine alkaloids, providing evidences of their differential compartmentalization.

Resumo em Inglês:

A molecularly imprinted electrochemical sensor for determination of isoamyl alcohol was successfully constructed by modifying the glassy carbon electrode (GCE) with gold nanoparticles (AuNPs) and reduced graphene oxide (RGO). The modification of the GCE increased the electron transfer rate and the electrode surface area, which, consequently, made more room available for the formation of the molecularly imprinted polymer (MIP). The development of the MIP on the modified surface was carried out via electropolymerization of the pyrrole in acetate buffer solution in the presence of the target molecule. The MIP-AuNPs-RGO/GCE showed low limit of detection (8.4 × 10-8 mol L-1), satisfactory quantification range, amperometric sensitivity of 1.1 A L mol-1, excellent reproducibility and stability. Even when in the presence of analogous molecules, the sensor exhibited excellent selectivity. These results suggest that the proposed sensor is suitable for the detection of isoamyl alcohol in fusel oil samples.

Resumo em Inglês:

In this study, the extraction and characterization of aquatic humic substances (AHS) from two blackwater rivers in the Amazon basin was carried out in order to assess the seasonal effects in the AHS structure. In addition, an investigation of the complexing capacities (CC) of the structures containing the metal ions CdII, NiII and PbII was also done. The characterization (of the AHS) was done using UV-Vis, molecular fluorescence, and infrared spectroscopy. AHS from the Negro River showed more aromatic characteristics in its structures and molecular weight, than the AHS from the Carú River. The AHS studied presented a seasonal pattern characterized by higher humification levels during the rainy season. For all the metals, the AHS complexing capacity was higher for the Negro River. The highest complexing capacities were observed for the NiII assays, which were 0.56 and 0.12 µmol NiII mg-1 dissolved organic carbon (DOC), for AHS RN and AHS RC-II, respectively. We concluded that the transport, bioavailability, and toxicity, of these metal species should be higher for Carú River.

Resumo em Inglês:

The usefulness of molecularly imprinted polymer assisted paper spray ionization mass spectrometry (MIP-PSI-MS) for the determination of methamphetamine in urine has been demonstrated. MIP-PSI-MS is a method in which a MIP is synthesized on the surface of a paper, producing a chemically selective paper surface with molecular recognition sites for a target analyte. The analyte is extracted by the MIP substrate, which is posteriorly used for conventional PSI-MS analysis. As methamphetamine is one of the most widely used drugs of abuse in the world, it was selected to be studied in synthetic urine by the MIP-PSI-MS method. Methamphetamine was detected at higher ion signals compared to other different drugs, such as lysergic acid diethylamide (LSD) and cocaine, suggesting that MIP-PSI-MS has a chemical affinity for methamphetamine. In experiments to validate the method, a linear calibration curve was achieved with R-squared (R2) > 0.99. Limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.8 and 2.8 µg L-1, respectively. Precision (relative standard deviation) and accuracy (relative error) were less than 10%, and the recoveries were close to 100%. The matrix effect was below 10%. These data demonstrate the possibility of using MIP-PSI-MS as an analytical tool for a specific/selective analysis of methamphetamine in forensic sciences.

Resumo em Inglês:

A simple and efficient method using reduced amounts of solvents for the determination of polycyclic aromatic sulfur heterocycles (PASHs) in aqueous matrices from a lagoon and leachate solid waste from a petrochemical industry is proposed. The target analytes were previously concentrated using the disposable pipette extraction (DPX) technique applying gas chromatography-mass spectrometry (GC-MS) for analysis. In this innovative approach, the DPX was modified with 8-hydroxyquinoline silica gel immobilized with PdII for the pre-concentration of 4-methyldibenzothiophene, 4,6-dimethyldibenzothiophene, 1,2-naphtobenzothiophene, 2-methylbenzothiophene and 3-methylbenzothiophene. To improve the extraction efficiency, parameters such as desorption solvent, ionic strength, extraction and desorption cycles were optimized. The values obtained for the limits of detection (LOD) and quantification (LOQ) are adequate for the determination of PASHs in aqueous and leachate solid waste samples. Precision and accuracy parameters showed satisfactory results, providing relative recoveries of 74.6-131.2% for PASHs from lagoon water samples and 72.7-118.0% for leachate of solid waste samples. In the lagoon samples the relative standard deviation (RSD) values for the five PASHs ranged from 0.3 to 9.2% and 3.8 to 19.4% for the leachate of the solid waste. These results demonstrate that the proposed method represents a promising alternative for the determination of PASHs in aqueous and leachate solid waste samples.

Resumo em Inglês:

Cu-Co-containing cellulose-based carbon composite materials (Cu-Co/Cel) were formed by a matrix isolation method. Using X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared-Fourier spectroscopy (IR-Fourier spectroscopy), and non-isothermal research methods, the physicochemical properties of the composites were established. The catalysts are nanosized particles distributed in a carbon matrix, containing fragments of a system of conjugated bonds (C=C-C=C) of various lengths. Cu-Co/Cel catalysts are active in the synthesis of alcohols from CO and H2, demonstrating high CO conversion (68%) and specific activity (17 mol CO gMe-1 s-1). Differences in the mechanism of alcohol formation from CO and H2 on cellulose-based composites and an oxide support (comparison catalyst) were shown by analyzing the distribution of synthesis products.

Resumo em Inglês:

Staring Bay has long been used by the local community for fisheries and fishing activities; however, the rapid population growth and industrial activities around the bay in recent years are predicted to contribute significantly to the increase of waste entering the bay. This particular study was aimed to provide baseline levels of trace elements Pb, Cu, Ni, Fe, and As in this bay. Concentration and spatial distribution of trace elements were analyzed to determine the pollution status of the bay. An inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify elements content. The concentrations of trace elements varied from 0.049-0.685 µg L-1 (average: 0.261 ± 0.163 µg L-1) for Pb, 0.170-1.278 µg L-1 (0.475 ± 0.252 µg L-1) for Cu, 0.375-1.469 µg L-1 (0.754 ± 0.258 µg L-1) for Ni, 0.544-69.290 µg L-1 (8.036 ± 13.779 µg L-1) for Fe, and 0.952-1.721 µg L-1 (1.366 ± 0.168 µg L-1) for As. The present study suggests that Staring Bay has been highly contaminated by trace elements Pb and Fe relative to their normal oceanic levels. The contaminated areas were found in the estuaries due to terrestrial anthropogenic inputs from industrial and agricultural activities, residential areas and brackish ponds.

Resumo em Inglês:

This report describes a rapid and inexpensive colorimetric method based on biuret assay for total serum protein analysis using wax printed microzone plates and a desktop scanner. The colorimetric assay was performed in 96-microzone plates fabricated on polyester films through a wax printing protocol. The image scanning mode and the concentration of the biuret reagents were optimized to achieve the highest detectability levels. The best analytical response was obtained using the slide scanning mode as well as 4% CuSO4 and 150 mmol L-1 potassium sodium tartrate solutions. The proposed method offered linear relationship for the bovine serum albumin concentration range between 25 and 200 µmol L-1 with a limit of detection of 9.7 µmol L-1. The colorimetric approach revealed satisfactory precision (relative standard deviation values between 0.6 and 4.4%). The bioanalytical feasibility was demonstrated through the total protein analysis in serum samples collected from dogs previously diagnosed with kidney disease. The total serum protein concentrations varied from 960 ± 19 to 1661 ± 38 µmol L-1 and the achieved values revealed good accordance with those obtained through a reference method. Based on the reported results, wax printed microzone plates have demonstrated simplicity and potential to be adopted as alternative platforms for bioassays.

Resumo em Inglês:

The presence of protein in the natural rubber latex for the medical device manufacture seems to be the most considered compound due to its allergic effect. Magnetic coated alumina (Fe3O4@Al2O3) has been known as an adsorbent for organic substrates due to its performance through physical and/or chemical interaction. In the current study, we tried to figure out the potential of Fe3O4@Al2O3 to prepare low protein’s natural rubber latex with and without the presence of surfactant through a continuous batch system. The dry rubber content, surfactant amount, and time during the incubation were investigated to determine the effective protein removal natural rubber. The highly deproteinized natural rubber was confirmed using Kjeldahl method, proven that the utilization of Fe3O4@Al2O3 could reduce the protein content from 0.38 to 0.016% in an optimum condition (dry rubber content of 10.00%; surfactant of 0.25%; Fe3O4@Al2O3 of 1.00 wt.%; and 15 min of incubation time). These results showed that Fe3O4@Al2O3 is a very good material to remove protein from natural rubber latex and this method can be performed using a continuous batch system.

Resumo em Inglês:

The development of a method based on extraction induced by emulsion breaking (EIEB) aiming copper determination in gasohol using graphite furnace atomic absorption spectrometry (GF AAS) is reported. Emulsification of the gasohol samples was carried out using nitric acid solution, (1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol surfactant (Triton X-114), and ultrasound energy. The variables related to the extraction efficiency were optimized by multivariate approaches (two-level factorial fractional design and Doehlert design). The best results were obtained when the emulsion was formed with 5.0 mL of the sample, 0.200 mL of 2.4 mol L-1 HNO3, 0.100 mL of 10% Triton X-114 and 10 min of sonication. A fast and efficient emulsion breaking was performed at 90 ºC. A volume of 6.65 mL of the copper-rich hydroalcoholic phase was extracted, separated from the organic phase and analyzed. Under these conditions, the following analytical characteristics were obtained: 0.61 and 2.0 µg L-1 for limits of detection and quantification, respectively; precision (percentage of relative standard deviation, 10 µg L-1) of 2.8%; and analytical sensitivity of 0.011 L µg -1. Accuracy was assessed by spike tests, and values in the range of 95-110% were achieved. The method was applied in the determination of copper in Brazilian gasoline samples (gasohol with 27% ethanol).

Resumo em Inglês:

An infection of the fungus Moniliophthora perniciosa in cocoa trees reduces productivity of the plant. In this study, the concentrations of mineral nutrients in healthy leaves and in leaves of vegetative broom of the cocoa plant were determined, and the relationship between the disease and the nutritional composition of the leaves was assessed. The samples were analyzed using the wet digestion method and the concentrations were determined by inductively coupled plasma optical emission spectrometry and the Kjeldahl method. Results indicate that leaves of vegetative broom have lower concentrations of Ca, Mg, S, Fe, Mn, and Ni than healthy leaves. Concentrations of P and Cu were lower in healthy leaves and higher in leaves of vegetative broom. In contrast, concentrations of K, N, and Zn were the same for both types of leaves. In short, plant-fungal interaction was reflected in the nutritional composition of the leaves, demonstrated by the differences in nutrient concentrations between healthy and infected leaf tissue.

Resumo em Inglês:

Morita-Baylis-Hillman adducts (MBHA) is a class of polyfunctional molecules that has been standing out due to their versatility and expressive biological activities. Therefore, this paper describes the synthesis and antiproliferative activity of some new MBHA/7-choroquinoline hybrids. The Michael acceptors were obtained starting from 4,7-dichloroquinoline which were submitted to the Morita-Baylis-Hillman reaction with ortho, meta and para-nitrobenzaldehyde. The in vitro screening of the synthetized MBHA against NCI-H292, HCT-116 and MCF-7 cancer cells suggests the influence of the spacer chain in its inhibition potential. The 50% inhibitory concentration (IC50) obtained in the antiproliferative assay using MCF-7, HCT-116, HL-60 and NCI-H292 cancer cells indicate expressive cytotoxic potential of the adducts containing nitro group in the ortho position, with IC50 of 4.60 µmol L-1. MBHA/7-choroquinoline hybrids were more active than MBHA described in literature, indicating the improvement of the cytotoxic effect due to 7-chloroquinoline moiety in the molecular structure, with maximum selectivity index values of 11.89.

Resumo em Inglês:

Poly(3-hydroxybutyrate) (PHB) has been proposed to be a potential candidate to be used as biomaterial. However, its poor processability, high brittleness and rigidity have limited its applicability. Transesterification reactions with poly(ε-caprolactone) (PCL), one of the most promising biomedical materials, emerge as an attractive alternative to improve its mechanical properties. In this work, poly(3-hydroxybutyrate-b-ε-caprolactone) (PHB-b-PCL) was prepared straightforwardly by transesterification of the parent homopolymers by reactive extrusion in the presence of stannous octanoate. After purification by solvent fractionation, PHB-b-PCL was characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy of carbon (13C NMR) and hydrogen (1H NMR) and, subsequently, submitted to electrospinning. The results indicate that PHB was modified, showing lower crystallinity as compared to the original homopolymers. The electrospun mats are tough and flexible and analysis by scanning electron microscopy indicates the formation of uniformly smooth morphology with average fiber diameter of 900-1200 nm and voids in the range between a few microns up to a few tens of microns, suitable for cell diffusion in biomedical applications.

Resumo em Inglês:

Classrooms are microenvironments in which children and teenagers may be exposed to fine particulate matter (PM2.5). Iranduba is a rural city in the Amazon region close to many brick kilns and road with high traffic levels. In this study, indoor and outdoor PM2.5 levels were measured in a classroom in Iranduba, and the PM2.5 exposure effects on student’s health were calculated. High indoor PM2.5 concentrations and high indoor-to-outdoor ratio values indicated particle accumulation within the classroom. The high percentage of black carbon (10%) in the dry season revealed the influence of burning processes on PM2.5 composition. Se, S, and Pb had an enrichment factor > 5, indicating that there is an important source for these elements in the city. The positive matrix factorization (PMF) model indicated soil resuspension, burning processes and vehicular emissions as the main PM2.5 sources. The excess risk shows that our classroom occupants are expected to be 30% more likely to develop lung-cancer than a group exposed to a background level of PM2.5. Therefore, it is important to have an effective ventilation system in order to reduce the accumulation of pollutants within the classroom and also to control/decrease the emission of pollutants in the city.

Resumo em Inglês:

The properties of lanthanides allow them to be used as contrast agents for magnetic resonance imaging, thereby helping to differentiate between tissues, organs, and pathologies more efficiently. Lanthanides contain thermosensitive energy levels that aid identification of cancer and healthy cells. This work investigates the GdVO4 matrix obtained by the non-hydrolytic sol-gel methodology and doped with the lanthanide ions Er3+ and Yb3+ at a 1:1 molar ratio. The efficiency of the optical parameters was analyzed on the basis of the Er3+ green emission after excitation in the infrared region, namely 980 nm. The temperature-dependent fluorescence intensity ratio (FIR) between the thermally coupled Er3+ levels (2H11/2 and 4S3/2 → 4I15/2) was evaluated. The Er3+ emission depended on the laser power. The calculated number of photons was 2 in this case. Temperatures ranging from 298.3 to 374.5 K were assessed, and the sensitivity varied from 1.2 to 1.9% K-1, respectively. The initial temperature was estimated.

Resumo em Inglês:

Croton grewioides Baill. popularly known as “canelinha” or “canelinha-de-cheiro” has been used for the treatment of influenza, antitussive, febrifuge and headache; however, the study of its phytochemical composition is limited. The aim of this study was to investigate the effect of the extraction method and seasonality through leaf extracts of four accessions of Croton grewioides by fingerprint chromatograms aided by principal component analysis to analyze the differences and similarities among the samples. We aimed also to provide chemical characterization of isolated secondary metabolites using semi-preparative liquid chromatography. The results showed that only the chemical profile of the methanolic extracts of accessions 101 and 113 were influenced by the seasonality. For the first time, four flavonoids were isolated through semi-preparative chromatography in this species, characterized as quercetin 3-O-β-D-galactopyranosyl-(1→2)-α-L-rhamnopyranoside-(1→6)-α-L-rhamnopyranoside (1), quercetin 3-O-β-D-galactopyranosyl-(1→2)-α-apiopyranoside-(1→6)-α-L-rhamnopyranoside (2), quercetin 3-O-glucopyranoside (3) and 3-O-methyl-quercetin (4), the flavonoid (2) has been recognized as a new triglycosylated derivative.

Resumo em Inglês:

Arylation reactions are an important class of reactions and allow the synthesis of natural and synthetic products. Despite the efficient, but high cost and toxic methodologies involving transition metals, radical arylations have gained importance after the advent of photoredox catalysis. Arylation of enol acetates is an important tool for obtaining aryl ketones but the scope of the reaction is limited to the pattern of substitution at phenyl radical and α-carbon of the enol. Theoretical calculations ((U)BHandHLYP/6-311G**) show that the polar effect is the key factor in this reaction. A good correlation of calculated rate constants with field effect explained why phenyl radicals with electron-withdrawing groups react faster toward enol acetate. The presence of alkyl groups at α carbon at the enol showed some influence of enthalpic effect but strong influence of steric effect, evidenced by great correlations with Taft and Charton parameters. Finally, substitution at β carbon showed no significant effect at reaction rates.

Resumo em Inglês:

We are introducing an alternative analytical expression to the electronegativity difference (∆χ) as a function of the charge ge, g is the charge factor, the fraction of the electronic charge devoted to the bond and e the elementary charge, the packing factor (p) and the effective atomic number (Zeff) of binary ionic solids, by using the very basic Coulomb interaction, modified by the introduction of p, and the relationship between the electric dipole moment (µ) and ∆χ in Debye units. When compared to the Pauling’s, Gordy’s, Allred-Rochow’s and Allen’s scales, our calculations deviate around 10% to all ionic crystals with such data available in the literature. A very simple expression with satisfactory estimates, with no need of numerical procedure, is announced. The values of g play the important role of indicating the character of the chemical bond. It opens up an alternative opportunity to understand the nature of ionic chemical bonds and is able to describe the character of the bonding in any ionic polyatomic system.

Resumo em Inglês:

The corrosion inhibition of mild steel by aqueous extract of cumaru (Dipteryx odorata) seeds and its high molecular weight fraction (HMWF) was investigated in 1 mol L-1 HCl solution. The study was carried out through gravimetric essays, open circuit potential measurements, anodic and cathodic polarization curves and electrochemical impedance analyses, as well as morphological analysis of the mild steel by scanning electron microscopy. Gravimetric tests showed that the inhibition efficiency (IE) increased with immersion time and inhibitor concentration, reaching 98% of IE using 100 mg L-1 of the HMWF, after 6 h immersion time. The activation energy (Ea) increased with the addition of both inhibitors which characterizes a physical adsorption of the constituents of the aqueous extract of cumaru on the metal surface. Polarization curves indicated that both aqueous cumaru seeds extract and its HMWF act as mixed-type inhibitor. Impedance results showed a decrease in double layer capacitance (Cdl) and an increase in charge transfer resistance (Rct) evidencing a typically screening effect. The adsorption of molecules present in the aqueous extract of cumaru followed the Langmuir isotherm. The aqueous cumaru seeds extract was characterized by Fourier transform infrared spectroscopy (FTIR), 1H, 13C and 2D nuclear magnetic resonance (NMR).

Resumo em Inglês:

The compound 1,4-pentadien-3-one,(1E,4E)-1,5-diphenyl-2-(2,4-dinitrophenyl)hydrazone presents the molecular formula C23H18N4O4 and was prepared in an undergraduate laboratory. The hydrazone was synthesized from the condensation between dibenzalacetone and 2,4-dinitrophenylhydrazine (DNPH) and crystallized employing water/acetone liquid-liquid diffusion. The structure presents three aromatic rings connected by an unsaturated Y-shaped system. Dinitro substituted and one of the other aromatic rings are 15º out of a coplanarity, while the other phenyl group is almost orthogonal to the first (89º). The only observed classical hydrogen bonding is an intramolecular N-H···O. The supramolecular structure was analyzed employing the Hirshfeld surface and that is organized through C-H···O hydrogen bond and C-H···π, polar-π, and π-stacking. An interaction involving NO2···NO2 was also observed.

Resumo em Inglês:

The objective of this study was to develop a low-cost and eco-friendly adsorbent from agro-industrial waste for the removal of hexavalent chromium in the aqueous medium. The adsorbent (BMC) produced from yellow mombin (Spondias mombin L.) seeds was characterized by the determination of the chemical composition, thermal analysis (thermogravimetric (TG) analysis and differential thermal analysis (DTA)), Fourier transform infrared spectroscopy (FTIR), pH in suspension and determination of the point of zero charge (PZC). The presence of proteins, fats and carbohydrates (15.690, 1.004, and 73.706%, respectively) suggests that the material can be a promising adsorbent, given the availability of functional groups. The following conditions were set: pH 2.0, adsorbent mass 450 mg, and equilibrium was reached after 80 min. The maximum adsorption capacity was approximately 98%. Kinetic studies showed that the pseudo-second-order kinetic equation was the one that best adjusted to the experimental data. Under the conditions investigated, the Langmuir isotherm model described the best balance data, signaling the adsorption in monolayer. According to the results, it was found that the BMC showed an outstanding performance for the removal of CrVI ions and may become a viable and efficient alternative for the treatment of industrial effluents containing trace elements.

Resumo em Inglês:

In the present work five acetylene derivatives (1-5), including three unknowns (1, 3 and 4), were isolated from seeds of Porcelia macrocarpa (Annonaceae). The structures of isolated compounds were determined as docos-13-yn-21-enoic acid (1), 3-hydroxy-4-methylene-2-(eicos-11’-yn-19’-enyl)but-2-enolide (2), 3-hydroxy-4-methylene-2-(octadec-9’-yn-17’-enyl)but-2-enolide (3), 3-hydroxy-4-methylene-2-(hexadec-7’-yn-15’-enyl)but-2-enolide (4), and (2S,3R,4R)-3-hydroxy-4-methyl-2-(eicos-11’-yn-19’-enyl)butanolide (5) by analysis of nuclear magnetic resonance (NMR) and electrospray ionization high-resolution mass spectrometry (ESI-HRMS) data. Moreover, all isolated compounds demonstrated selectivity towards intracellular amastigotes of Leishmania (L.) infantum, especially 2-4 with 50% inhibitory concentration (IC50) values of 9.2, 10.4 and 11.0 µM, respectively, indicating superior activity of that determined to positive control miltefosine (IC50 of 17.8 µM). Furthermore, these compounds showed higher selectivity index (SI) in comparison with miltefosine. Since related acetylene fatty acid 1 displayed reduced antiparasitic potential (IC50 of 48.5 µM), the obtained results suggested that the γ-lactone plays an important role in the antileishmanial activity. However, 2-4 exhibited cytotoxicity to mammalian NCTC cells (CC50 ca. 80 µM), which could be a result of the presence of a conjugated carbonyl system in the lactone ring, since 5, the only acetogenin that presents the saturated ring, lacked mammalian cytotoxicity (CC50 > 200 µM).