Resumo em Inglês:

The restoration of acetylcholine levels in the brain by inhibition of cholinesterases is currently the most successful therapeutic strategy to treat neurodegenerative disorders. In this context, tacrine has been largely investigated as a starting scaffold for the development of promising new anticholinesterases compounds for the treatment of neurodegenerative illnesses, including Alzheimer’s disease. Here we present a series of compounds containing the tacrine nucleus connected with squaric moiety by a diaminoalkylene chain. The compounds were obtained through a simple and short synthetic route and showed high inhibitory activity against acetylcholinesterase (AChE) within nanomolar IC50 (half maximal inhibitory concentration). The molecular modelling study showed that these compounds act as dual-binding inhibitors of AChE, interacting with both catalytic active site (CAS) and peripheral anionic site (PAS) of the enzyme’s binding cavity. The investigated compounds also demonstrated outstanding selectivity for AChE than in butyrylcholinesterase (BuChE). These results evince these compounds as promising agents for the treatment of neurodegenerative disorders and a fuller synthetic scope jointly with complementary biological evaluations are currently under investigation in our laboratory.

Resumo em Inglês:

We reported experimental and theoretical investigation of conformers of 1,2,3-triazole derivatives, substances of exclusively synthetic origin, subject of extensive studies, because of several biological properties, such as antiviral, antimicrobial and antileishmaniasis. We reported molecular/supramolecular X-ray structures of antiophidian compounds I and II. For I and II there are two crystallographic different molecules in the unit cell (A and B). To explore the causes of the similarities in the compound’s crystal structures, intermolecular interactions were explored using the Hirshfeld surface as the fingerprint plots. In addition, density functional theory (DFT) calculations were carried out at the ωB97x-D/6-31G(d,p)-PCM-CHCl3 level aiming to contribute to the interpretation of the experimental data and complement the experimental findings. Two structures named 2A and 5B were found in good agreement with the respective X-ray solid state ones (A and B). Theoretical 1H nuclear magnetic resonance (NMR) spectra calculated for 5B rotated structure (torsion angles deviation around 40° to 90°) was in fine agreement with experimental results (in CDCl3) indicating that the solution molecular structure is considerably different from optimized equilibrium geometries and solid-state structure. Therefore, care is needed when using X-ray structures or DFT geometries to model interaction of drugs with biological targets since significant conformational changes may take place in solution.

Resumo em Inglês:

In this work, the reaction parameters for polymeric carbon nitride synthesis by thermal polycondensation were assessed, such as type of precursor, heating rate and time of thermal treatment, in order to obtain crystalline materials with high photocatalytic performance. All synthesized materials were tested as photocatalysts in hydrogen production using ethylenediaminetetraacetic acid (EDTA) as a sacrificial reactant under visible light irradiation (λ ≥ 420 nm). The synthesis condition capable to obtain the material that reached the best performance in photocatalytic hydrogen production was using thiourea as the precursor, due to the band gap narrowing and charge recombination suppression; an intermediate heating rate (5 ºC min-1) and a longer thermal treatment time (6 h) that yielded a better crystalline solid. The combination of these effects led the S-doped polymeric carbon nitride (SPCN4 sample) to a higher photocatalytic activity, reaching the maximum hydrogen production rate of 214.75 µmol g-1 h-1.

Resumo em Inglês:

Cannabis sativa has many promising medicinal applications for the mitigation, or even cure, of chronic diseases. The high bioaccumulation potential of C. sativa enables its use for the phytoremediation and detoxification of soil, may increase the levels of inorganic elements in products such as cannabidiol (CBD) extracts being necessary the evaluation/monitoring of the level of inorganic components, mainly the toxic species in these formulations. An analytical method employing graphite furnace atomic absorption spectrometry (GFAAS) was developed for the quantification of Pb, As, and Cd in commercial CBD extracts and homemade samples. The alkaline solubilization was employed in agreement with the external analytical curve, in a robust method. The limits of quantification were 0.26 (Pb), 0.067 (As), and 0.011 µg g-1 (Cd), with satisfactory accuracy (80-120%) and relative standard deviation (RSD) values < 7%. The CBD extracts presented levels of Pb, As and Cd below the maximum limits established by regulatory agencies.

Resumo em Inglês:

Cocos nucifera L. is a palm tree of paramount importance in the food and chemistry industries, although over 50% of its biomass is discarded as waste. The aim of the study is to investigate different pretreatments in to coconut husks (CH), based on acid, alkaline, ionic liquid (IL), and peroxidative, in order to produce fermentable sugars. Severity factors were calculated for pretreatments; values ranged from 0.3 to 1.7 for peroxide, from 0.01 to 1.4 for alkaline, from 1.4 to 2.8 for acid and from 2.0 to 3.0 for ionic liquid. Pretreatments were optimized (time and temperature) to maximize the sugar yield and to remove the total lignin after acid hydrolysis. Reducing sugar yield (70%) was higher when CH waste was alkaline-pretreated for 2 h at 76.21 °C. The highest lignin removal rate was recorded when alkaline (21.4%) and peroxide solutions (27.2%) were used. The IL did not increase sugar yield and was not effective in lignin removal. These outcomes were confirmed through infrared spectroscopy, whereas scanning electron microscopy showed increased biomass porosity during alkaline, acid and peroxide pretreatments. The IL showed little and non-significant changes. The crystallinity index notably increased after each pretreatment; besides, it was directly associated with sugar content.

Resumo em Inglês:

The high worldwide consumption of antibiotics and their complex impurity profiles has drawn the attention of the scientific community to the development and validation of stability methods for these drugs. Amphotericin B is an antibiotic that is a natural fermentation product of bacterium Streptomyces nodosus, used as a broad-spectrum antifungal agent, and is highly unstable. For this reason, the objective of this work is the development and validation of an indicative method of stability by high performance liquid chromatography (HPLC) associated to diode array detector (DAD) for amphotericin B (AMB). To achieve this, the chromatographic profiles of acid, basic, oxidative and thermal degradation caused by AMB exposure to water and light were verified by HPLC-DAD, using an isocratic method under the following conditions: C18 chromatographic column (200 × 4.6 mm-5 µm), mobile phase composed of 65:35 of organic phase (methanol/acetonitrile in 41:18)/aqueous phase (2.5 mmol L-1 of disodium edetate, pH 5.0), flow rate of 1.0 mL min-1, injection volume of 20 µL, column temperature 30 ± 2 °C and wavelength of 383 nm. After identification of these profiles, the method was validated according to recommendations of the International Conference on Harmonization guidelines, and then, the active pharmaceutical ingredient (API) peak purity grade, percentage of drug degradation, occurrence of impurities peak and its identification by mass spectrometry (MS) with electrospray ionization (ESI), under positive ionization mode, were evaluated. It is suggested that the main degradation products were amphotericin B (2), degradation product 1 (DP1) and degradation product 2 (DP2) in acid and oxidative medium. Amphotericin B was stable in the presence of water and at 70 ± 2 °C for seven days.

Resumo em Inglês:

The amount and variety of new psychoactive substances (NPS) are expanding, and there are difficulties in assessing their risks. In this regard, in silico methods are potentially useful to predict NPS properties faster and at a lower cost. In this work a quantitative structure-activity relationship (QSAR) model was used to verify the risk of drugs derived from amphetamines and cathinones. A dataset of 26 derivatives with in vitro affinity for norepinephrine transporter (NET) was selected. To ensure reproducibility of the results, only geometric molecular descriptors (AM1 (Austin model 1) level) obtained from the platform ChemDes and ordered predictors selection (OPS) were used. The model presents good internal statistics (n = 23; coefficient of determination (R2) = 0.914). The small number of samples was divided into seven training sets (n = 17) and seven test sets (n = 6). The average R2pred = 0.754 showed that the model has good predictive capacity. Based on the tests, this model can accurately predict the risk range of three previously selected derivatives: methedrone (low), ethcathinone (medium), and methamphetamine (high), even when only data referring to NET are employed. We used these data to create a simple free program in Java that focuses on the risk assessment of recreational drugs belonging to this class of compounds.

Resumo em Inglês:

Biochar is a rich-carbon material highly functionalized, which allows the use as electrodes modifier for preconcentration and voltammetric determination of several species. This work describes a castor cake biochar production and chemical activation with different reaction conditions using HNO3 and/or H2O2. Biochar samples were characterized using scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, Raman and zeta potential. Carbon paste modified electrodes (CPME) have been constructed using different biochar samples to evaluate the adsorptive capacity for the spontaneous preconcentration and voltammetric determination of Pb2+, Cd2+, Cu2+ and Ni2+ ions, paraquat and methyl parathion pesticides. The activation treatments promoted modifications in the elemental, morphological and structural biochar characteristics. Activated biochar CPMEs showed increase in the current signal around 15 and 2.5 times higher than unmodified and precursor biochar electrode, respectively. N2 sample (HNO3, 60 °C for 3.0 h) presented the better response signals for all compounds. This was attributed to the more effective surface oxidation, promoting a high porosity, acid character and amount of acid functional groups. Besides that, this greater analytical response allows the CPME-N2 application as a passive sampler for the voltammetric determination of inorganic and organic contaminants for environmental management in aqueous matrices.

Resumo em Inglês:

New diesters derived from phthaloylglycine (7a-7i) were synthesized and their structures characterized by infrared, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The compounds were evaluated in an in silico study, which demonstrated positive features indicating a possible drug candidate. The diesters showed antifungal activity ranging from moderate to strong against strains of Candida. Compounds 7a, 7b, 7c, 7e and 7i had a moderate minimum inhibitory concentration (MIC) of 1024 µg mL−1 against all fungal strains, while 7h showed a very good MIC of 256 µg mL−1 against Candida albicans, Candida parapsilosis and Candida krusei and 64 µg mL−1 against Candida tropicalis. However, only 7h and 7i were able to inhibit bacterial growth of strains of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli with an MIC of 1024 µg mL−1.

Resumo em Inglês:

An alternative approach for carbaryl determination based on the change in the oscillation period of the Belousov-Zhabotinsky (BZ) reaction under the addition of carbaryl is demonstrated. The oscillations were observed by spectrophotometric measurement at 320 nm, corresponding to the maximum absorption wavelength of cerium(IV) catalyst. The oscillation periods increase with the carbaryl concentrations, which can be discussed based on the Field-Körös-Noyes (FKN) mechanism. The increase of oscillation periods is proportional to the concentration of carbaryl in the range of 0.1-200 mg L-1 with the regression coefficient of 0.9938. The limits of detection and quantification were 0.044 and 0.147 mg L-1, respectively. The precisions in terms of intra-day and inter-day measurements were efficient with relative standard deviation (RSD) lower than 2.1%. Accuracy of carbaryl in different water samples was obtained with high recoveries in the range of 94-106% and also comparable to the results of high performance liquid chromatography (HPLC) analysis. The proposed method is precise, cost-effective and can be alternatively employed for the screening and determination of carbaryl residues in water samples.

Resumo em Inglês:

Zn2Al-Cl and Zn2Al-NO3 layered double hydroxides (LDHs) were synthesized through the fixed pH co-precipitation method and used as precursor materials for the intercalation of p-aminobenzoate through anion exchange reactions. Since chloride in Zn2Al-Cl was only partially exchanged with p-aminobenzoate, the phases Zn2Al-NO3 and Zn2Al-N -AB (nitrate exchanged with p-aminobenzoate) were used in different percentages as functional fillers to produce nanocomposites of low-density polyethylene doped with maleic anhydride (LDPE). Analysis of thermal properties showed that the melting and recrystallization temperatures were slightly increased in the nanocomposite containing 5 wt.% Zn2Al-N-AB. Weathering tests performed with neat LDPE and the nanocomposite films showed that the addition of the LDHs improved ultraviolet (UV) absorption and reduced the LDPE degradation by 25 and 76% when using Zn2Al-NO3 and Zn2Al-N-AB, respectively, as fillers, showing a promising UV-shielding effect. Preliminary results also showed a potential application of Zn2Al-N-AB as antioxidant in natural insulating oils (natural ester FR3 and castor oil), opening new opportunity of applications.

Resumo em Inglês:

In this study, we successfully demonstrated a strategy for specific disulfide bond formation by hybridization of two complementary peptide nucleic acid strands. Peptides were linked to the pair of complementary peptide nucleic acids by native chemical ligation, respectively, and base pairing drove the two peptides into close proximity for interchain disulfide bond formation. Since peptide nucleic acids directed system is easier to manipulate than deoxyribonucleic acid system, this system will be more useful and have a broader application scope in the construction of complex biomolecular structures.

Resumo em Inglês:

The known biotechnological properties of chitosan and the recent biological activities attributed to polysaccharides from Agaricus brasiliensis have been of interest to obtain films constituted by these two polymers. The glucans obtained from the mushroom inhibited about 96.5% of the ferrous ion, besides not promoting a significant increase of lactate dehydrogenase enzyme (LDH), which indicates that the polysaccharide is able to inhibit the production of radical species and also presents low cytotoxicity to the biological systems. The results of spectroscopy analyses in the infrared region (FTIR) and X-ray diffraction suggest an existing electrostatic interaction between the substances. A reduction in the films’ swelling capacity was observed with an increase in the polysaccharide content in the composition. In addition, scanning electron microscopy (SEM) revealed greater surface density of the films. In convening the biological properties of the substances, it is expected that this study raises interest in evaluating the films and their capacity for healing wounds and burns.

Resumo em Inglês:

The design of a series of styrene and spiroisatin hybrids was based on the structure of combretastatin A-4 1. This library of 20 compounds were synthesized with the pharmacophoric units: 3,4,5-trimethoxy or/and 4-hydroxy-3-methoxy phenyl moities in their structure. Thereby, the libraries of β-nitrostyrenes 10a-10c, spiroisatin-dihydroquinolines 14a-14c, spiroisatin-thiazolidinones 17a-17c and spiroisatin-nitropyrrolizidines 20a-20k were evaluated for their in vitro cytotoxic, anti-proliferative, antifungal and antiviral activities. Biological results revealed that among these compounds, β-nitrostyrenes 10a-10c exhibited significant cytotoxicity (HeLa and Jurkat tumor cells) and antifungal (T. mentagrophytes) activities. Moreover, the spiroisatin-dihydroquinoline 14a and 14c showed promising cytotoxicity (U937 cells). 14a-14c molecules were active against human herpesviruses serotypes 1 and 2 (HHV-1 and HHV-2), but only 14a and 14b were effective against dengue virus serotype 2 (DENV-2). The spiroisatin-nitropyrrolizidine 20c exhibited moderate anti-herpetic activity, while 17c spiroisatin-thiazolidinone derivative also reduced the infection of HHV-1 and DENV-2. Finally, the molecular docking showed that these kind of molecules interact with the subunit α/β-tubulin.

Resumo em Inglês:

Biodiesel purification by water washing has been proved to be an unattractive process from an economic and environmental point of view. In this work, we propose the use of regenerated cellulose membranes from peanut shell as an alternative in the biodiesel purification. The preparation of the membranes was optimized from a central composite design, resulting in dense and non-porous membranes. However, in contact with biodiesel, the membranes undergo expansion due to the retention of methanol, water, and glycerol molecules, allowing the permeation of fatty acid methyl esters. The filtered biodiesel presents quality parameters, such as total ester content of 98.3 ± 1.4% and free glycerol content < 0.02%, in agreement with the main regulatory agencies. The regenerated cellulose membranes from peanut shell are easily prepared, with high repeatability (relative standard deviation (RSD) < 1.8%) and are presented as an economical and environmental solution for the biodiesel purification.

Resumo em Inglês:

The collection time could be an important target for optimizing technological processes in obtaining essential oils of interest to agribusiness. The objective of this study was to distinguish the time for the collecting of Achillea millefolium L. leaves, which provides the highest yield and quality of the essential oil. Also, identify the type of polyethylene packaging and leaf storage period during the one-year period that would maintain the essential oil characteristics. Gas chromatography-mass spectrometry and chemometric studies were performed into two steps trial to detect changes in chemical profile induced by different conditions. First, an analysis of the leaf collection time was performed using chromatographic data from six different gathering times throughout the day. After determining the best time to collect from the leaves, the essential oil was extracted in five storage periods over a year. The highest oil content was observed in leaves harvested between 11 and 15 h, with a maximum of 39 min after 13 h. Therefore, it is recommended to perform extraction in the early afternoon. There was no significant statistical differentiation related to polyethylene packages. In addition, it is recommended that the essential oil can be stored without significant changes for up to six months.

Resumo em Inglês:

The roots of Solanum paniculatum (Solanaceae) have extensively been used in folk medicine to treat liver infections and as a diuretic. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) were used for the profiling and structural characterization of alkaloids from the roots of S. paniculatum. Sixteen 3-aminofurostane alkaloids were characterized as novel compounds. In this study, three principal alkaloids were isolated in mixture, and their structures were established by different spectroscopic methods, including 1D, 2D nuclear magnetic resonance (NMR) experiments, and the high-resolution electrospray ionization (HR-ESI)-MS analysis. The isolated alkaloids were used to explore fragmentation pathways. Compound identification was based on the exact mass and fragmentation behaviors. Two compounds were identified as new natural compounds as: (25R)-3β-amino-furost-5-en-22α,26-diol O(26)-β-D-glucopyranoside (fatimagraine) and (25R)-3β-amino-furost-22-en,26-ol O(26)-β-D-glucopyranoside (bhattacharyyaine). The unambiguous assignments of 1H and 13C NMR data and chemical correction of the structure alkaloid jurubine are reported for the first time.

Resumo em Inglês:

Coarse particulate matter (PM10) concentrations and chemical composition were monitored from 2014 to 2017 at three sampling sites in the Metropolitan Region of Rio de Janeiro, namely Botafogo, Gávea, and Gericinó. All sites are located close to the 2016 Olympic Game arenas. The average annual PM10 concentrations were above the limits recommended by the World Health Organization (WHO) at all sampling sites. Of all the analyzed water-soluble ions, the highest concentrations were obtained for NO3-, SO42-, Cl- and Na+. Sulfate displayed a higher anthropic contribution (ca. 70%). Iron and copper were present in all samples, originated from soil resuspension and traffic (fuels and brakes, among others). Overall, civil works to restructure the city and the construction of the Olympic Game arenas increased PM10 and some of its constituent levels prior to 2016. After the Olympic Games, PM10 concentrations have decreased, due to governmental policies regarding traffic planning and civil work finalization.

Resumo em Inglês:

Gasoline and ethanol fuels have been adulterated with methanol in Brazil. Methanol is not permitted in concentrations greater than 0.5 vol% due its toxicity but its lower price stimulates the adulteration. A new approach for quantitative analysis of methanol in gasoline and ethanol fuels is reported employing high-performance liquid chromatography coupled with refractive index (RI) detector on C18 column (250 × 4.6 mm, 5 µm) using deionized water as mobile phase (0.6 mL min−1). The method showed good analytical performance in terms of linearity for methanol concentration ranging from 0.5 to 4.5 vol% (coefficient of determination (R2) = 0.999) and from 4.0 to 12.0 vol% (R2 = 0.998). The recoveries (accuracy) values ranged from 98.6 to 103.2%. The results indicated that the developed method is accurate and suitable for the determination of methanol in gasoline with ethanol and ethanol fuel as an alternative procedure to gas chromatography (GC)-based techniques.

Resumo em Inglês:

In this paper, we have applied state-of-the-art technologies and new investigations were developed focusing on obtaining simple and inexpensive molecules for treating cardiovascular diseases, as they are considered the leading cause of death in the world. For the first time, the inclusion complex of sulcatone (SU) and β-cyclodextrin (β-CD) was achieved (using a spray drier) and characterized making use of spectroscopic, thermal and computational methods. In addition, the system was evaluated regarding its vasorelaxant properties. Evidence of the inclusion complex formation was provided using different techniques, such as X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and 1H nuclear magnetic resonance (NMR) spectroscopies and then deduced by pharmacological experiments, which showed significant changes in relation to the initial material.

Resumo em Inglês:

The excess of capping agents used during the synthesis of nanoparticles is usually removed by solvent washing. The influence of the amount of polyvinylpyrrolidone (PVP) capping agent in the catalytic activity of palladium nanocubes was evaluated, after different numbers of washing cycles in the purification step performed after the syntheses of the nanoparticles. The effect of PVP amount on the hydrogenation of unsaturated carbon-carbon bonds was evaluated in terms of kinetic analysis and diffusion experiments. Five different catalysts were prepared utilizing the washing off procedure. All catalysts were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, small angle X-ray scattering spectroscopy and dynamic light scattering. The reaction presented strong influence by the amount of PVP, which was determined to be due to a balance between the amount of capping agent and the structure of the substrate.

Resumo em Inglês:

Epoxidation of monoterpenes, α-pinene, β-pinene, limonene, α-terpinene, and (R)-carvone was carried out by the in situ production of a peroxyacid rather than direct addition of such an expensive and difficult to handle chemical. Previous reports showed use of metal catalysts with high yields, while methodologies without catalysts at high temperature showed yields lower than 30%. The authors report a methodology that produces peroxyacetic acid in situ yielding up to 75% pure epoxide at room temperature avoiding the use of catalysts. The products were analyzed by gas chromatography mass spectrometry (GC-MS), and structures were characterized by 1H and 13C nuclear magnetic resonance (NMR).