Resumo em Inglês:

Grapes are among the most widely cultivated fruits in the world, with the majority of Brazilian production focusing on natural grape juice. In this work, a total of 40 samples of 2 types of natural grape juice were analyzed for the presence of 86 pesticide residues, with multiresidue extraction based on modified QuEChERS, by liquid chromatography with high-resolution mass spectrometry (LC-HRMS). Limits of detection and quantification were below 6 µg L-1 and 20 µg L-1, RSD < 20%, R2 > 0.99 and recovery ranged from 80 and 120%. Thus, the developed method was validated and good performance characteristics such as linearity, trueness, repeatability and inter-day precision were obtained. As results, 7 pesticides were detected in real samples (azoxystrobin, benalaxyl, carbendazim, tebuconazol, thiophanate-methyl, pyriproxiphen and pyrimethanil). The method was successfully validated for simultaneous evaluation of 86 multiclass pesticides residues levels, which was applied in 40 natural white and red grape juice market samples. The limits of quantification (LOQs) were low enough and the method was tested on samples showing its applicability, and therefore, this method can be used in routine analysis. Also, this work therefore also serves as an alert regarding the contamination of processed products.

Resumo em Português:

Sugarcane is considered one of the greatest alternatives for the biofuels sector due to the high potential in the production of ethanol and its respective by-products. Processes of converting degraded pastures into sugarcane crops have been increasingly common in Brazil, as well as the use of pesticides to control plant diseases and pests in several crops. The objective of this work was to evaluate the occurrence of 2,4-D, ametryn, tebuthiuron, fipronil and its degradation products (fipronil sulfide and fipronil sulfone) in clay and sandy soils when applied to pasture and sugarcane management. Solid-liquid extraction and liquid chromatography coupled to mass spectrometry were used to quantify the compounds. The optimized method was validated with the following parameters: linear range from 0.5 to 300 µg L-1; linearity (r) > 0.99; precision with CV from 1.0 to 15.0%; accuracy of 60 to 117%, instrumental limit of detection (LOD) from 0.1 to 1.0 µg L-1 and instrumental limit of quantification (LOQ) of 0.5 µg L-1 for all pesticides, except 2,4-D (5.0 µg L-1). Pesticides concentrations of the experimental farms ranged from 0.1 to 266 µg kg-1, with the highest concentrations found in the months of pesticide’s application. The results showed the persistence of some pesticides in the soils even after months of use.

Resumo em Português:

The synthesis, characterization, acute toxicity, antitumor activity, and histopathological analysis of a novel dinuclear platinum(2+) complex - [Pt(DACH-κ2N)µ-(C4H2O6-κ4O)Pt(DACH-κ2N)] - is reported. Through acute toxicity tests, it was possible to place the platinum complexes into categories according to the OECD protocol. The dinuclear complex was classified in category 2 (cisplatin - category 1; and oxaliplatin - category 2). Analyzing the interaction between dsDNA and dinuclear complex was observed an Tm increase, suggesting that the dinuclear complex-dsDNA interact probably through of the interstrand form. Evaluations of tumor masses extracted from mice inoculated with Ehrlich carcinoma demonstrated a percent of tumor inhibition similar for cisplatin and oxaliplatin, but statistically different and superior for the case of the dinuclear complex. Cisplatin and oxaliplatin showed 41.4 and 40.8% inhibition, respectively, while the dinuclear complex presented 66.3%. The histopathological analysis demonstrated that the group treated with cisplatin showed more significant tissue damage, moderate hepatic steatosis, and nephritis. The livers, spleens, and kidneys of the animals treated with the dinuclear complex were within the normality range with no tissue lesions, and absence of metastasis.

Resumo em Português:

Food additives are chemical substances added to improve organoleptic characteristics, in this context, there are several synthetic dyes, such as sunset yellow, tartrazine, erioglaucine, allura red, indigo carmine, and new coccine, that can also be identified through different analytical techniques such as infrared spectroscopy, UV-Vis spectrophotometry, high performance liquid chromatography with diode array detector and mass spectrometry. Therefore, the objective of this work was to compare methods developed for different analytical techniques, in order to identify the one that presents greater efficiency in certain applications. For this, the patterns of the dyes were analyzed, as well as their mixtures and foods that had them. As a result, the CLAE-DAD presents excellent selectivity and linearity of the calibration curves, but it presents higher LD and LQ values when compared to the UV-Vis, in turn the infrared provides information regarding functional groups and bonds. Mass spectrometry showed great capabilities in identifying the molecular formula and better selectivity in the absence of the erioglaucine dye. It is not feasible to indicate the best or worst analytical approach, but it is possible to point out which one is more suitable for each application. Regarding the quantification capacity, chromatography and UV-Vis are good alternatives, but in mixtures containing more than one dye, CLAE-DAD is more suitable due to the better selectivity. Regarding the identification capacity, mass spectrometry, especially FT-ICR MS, is the most appropriate technique to propose molecular formulas due to its high resolution and mass accuracy. The advantage of FTIR was the easier sample preparation, being able to analyze the dyes in the solid state.

Resumo em Inglês:

To identify natural bioactive compounds (NBCs) as potential inhibitors of spike (S1) by means of in silico assays. NBCs with previously proven biological in vitro activity were obtained from the ZINC database and analyzed through virtual screening and molecular docking to identify those with higher affinity to the spike protein. Eight machine learning models were used to validate the results: Principal Component Analysis (PCA), Artificial Neural Network (ANN), Support Vector Machine (SVM), k-Nearest Neighbors (KNN), Partial Least Squares-Discriminant Analysis (PLS-DA), Gradient Boosted Tree Discriminant Analysis (XGBoostDA), Soft Independent Modelling of Class Analogies (SIMCA) and Logistic Regression Discriminate Analysis (LREG). Selected NBCs were submitted to drug-likeness prediction using Lipinski’s and Veber’s rule of five. A prediction of pharmacokinetic parameters and toxicity was also performed (ADMET). Antivirals currently used for COVID-19 (remdesivir and molnupiravir) were used as a comparator. A total of 170,906 compounds were analyzed. Of these, 34 showed greater affinity with the S1 (affinity energy < -7 kcal mol-1). Most of these compounds belonged to the class of coumarins (benzopyrones), presenting a benzene ring fused to a lactone (group of heterosides). The PLS-DA model was able to reproduce the results of the virtual screening and molecular docking (accuracy of 97.0%). Of the 34 compounds, only NBC5 (feselol), NBC14, NBC15 and NBC27 had better results in ADMET predictions. These had similar binding affinity to S1 when compared to remdesivir and molnupirvir. Feselol and three other NBCs were the most promising candidates for treating COVID-19. In vitro and in vivo studies are needed to confirm these findings.

Resumo em Inglês:

Malvaceae sensu lato is a family containing about 245 genera and 4,465 species mainly distributed across tropical and subtropical regions worldwide. Species of this family usually contain alkaloids with anti-inflammatory, antinociceptive, antiparasitic, antimicrobial and anticancer properties due to its secondary metabolites. In this context, this review aims to checklist the alkaloids isolated from Malvaceae sensu lato species, evaluating their chemical profile and pharmacological potential, providing a broad and concise overview of these secondary metabolites. The results were collected from scientific databases such as Web of Science, Scifinder, Pubmed, ScienceDirect and Google Scholar, using the keywords “Alkaloids” and “Malvaceae”. Several pharmacological/biological activities are reported in literature for the most varied alkaloid nuclei, such as: vasorelaxation of the mesentery of rats (cryptolepinone), antitrypanosomal activity (waltherione) and anti-inflammatory and bronchodilator activity (vasicine), which highlights a succession of activities related to this class of secondary metabolites. Presented data report the importance of the Malvaceae sensu lato family, demonstrating the biological relevance of its alkaloids, in order to contribute to scientific knowledge and the development of new drugs.

Resumo em Português:

This work presents the development of a low-cost spin coater for thin film deposition as an alternative to commercial equipment that have high acquisition cost. The proposed spin coater uses a brushless motor taken from an unused hard disk, which is activated through the association of an electronic speed controller (ESC) and an Arduino microcontroller. During deposition, the rotating substrate is attached with a vacuum clamping system. For the control, the system uses a Hall effect sensor to read the engine speed. The rotation readings performed by the equipment sensor were validated with a tachometer. Finally, TiO2 films were deposited on glass substrates with ITO (Indium Tin Oxide) and characterized by UV-Vis spectroscopy to obtain the transmittance of the films at different rotation speeds.

Resumo em Português:

This report describes the fabrication of a low-cost magnetic separator holder combining 3D printing and compact neodymium blocks for allowing magnetic extraction and purification of RNA from samples collected by nasopharyngeal swab from patients infected by SARS-CoV-2. The device was designed to contain 24 entrances for plastic microtubes in an arrangement like a commercial device. The proof of concept of the proposed device was successfully demonstrated through the sample extraction and purification of swab samples collected from eight patients suspected of SARS-CoV-2 infection. The sample preparation protocol was performed using a commercial kit containing magnetic beads and different solutions. The performance of the printed device was compared to a commercial magnetic separator, usually employed in the golden standard techniques. The fabrication of the 3D printed magnetic separator was completed under optimized printing conditions within 6 h at cost of 4 USD per unit. The RNA extracted from samples using both devices was analyzed by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and the achieved results have indicated no statistical different at confidence level of 95%. Based on the achievements, the use of 3D printing and neodymium blocks have demonstrated an alternative route to be used in routing analysis associated to COVID-19 diagnosis.

Resumo em Inglês:

The experimental activities for undergraduate chemistry students play an important role to develop skills and expertise in that science thus, the practice-experimental classes are so important to achieve this purpose. This work deals with a demonstrative experience for dye separation from food coloring sample using liquid column chromatography. Beyond the experimental practice and the facility in visualizing the separation, this demonstration shows how a simple experiment involving alternative and easy access materials can promote a meaningful learning once it is possible to handle the acquired data, trace and analyze the results themselves, thus developing skills rather than the operational procedure. This proposal could be implemented in initial chemistry classes in Brazilian universities. Sea and river sands were used as stationary phases and aqueous ethanolic solutions were used as mobile phases. A food coloring (a mixture of 3 dyes) was chosen as sample to be studied. Chromatographic separation was followed by spectrophotometric measurements. A set of analyses were carried out to discuss the solubility of the food coloring, granulometric studies of the stationary phases used and electronic microscopy images of the sands studied here. As alternative materials were used in this work, a chromatographic column was also constructed with low-cost materials.

Resumo em Português:

Glass is one of the most important materials both in ordinary life, in which its presence is felt everywhere, as in the laboratory, be it a chemical or any other laboratory. This article discusses glass in many aspects, including its composition, or compositions, history and applications, both as a component of civilization as a practical and ordinary component in thousands of uses as an indispensable material. Also will be discussed many of its scientific applications, particularly in chemistry. A survey will also be presented of the origins and present state of glass techniques in Brazil.