Resumo em Inglês:

FMOC-Cl is a derivatizing agent widely used both in N-protection reactions of α-amino acids as well as in quantification and detection of amino acids and related molecules using HPLC-PDA or fluorescence analysis. In this work we studied the reaction of FMOC-Cl with gabapentin. However, it was observed that the degradation of gabapentin-N-FMOC and FMOC-Cl to FMOC-OH occur simultaneously in presence of the basic reaction medium which is specific for gabapentin derivatization. The degradation reaction is accelerated in temperatures above 45 °C and also by the time of contact of the reactant and product with basic medium. In this study, gabapentin derivatization reactions were shown to be cleaner and more efficient when an FMOC-Cl/gabapentin ratio of 2:1 was used, at 25 °C over a period of 15 minutes.

Resumo em Inglês:

This paper describes the evaluation of the total concentration of Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Mn, Pb e Zn and the bioaccessible fraction of Ba, Cu, Fe, Mn, Pb and Zn in samples of grape skins from different cultivars (Vitis Viníferas Tannat and Cabernet Sauvignon) by MIP OES. For the determination of total concentration, acid decomposition with a reflux system adapted to the digestion tubes in the oxidizing medium of HNO3 and H2O2 were used. The accuracy of the method was verified by recovery tests, whose values ranged from 80 to 120%, as well as through a comparative method in closed system. Bi, Cd and Cr showed values for total content below the LOD or below the values acceptable for health while Pb is higher than 0.2 mg kg-1, for both cultivars. To evaluate the bioacessible fraction, the gastrointestinal system was simulated using an in vitro procedure, and its performance was assessed considering the bioaccessible fraction (supernatant) and the non-bioaccessible fraction, whose sum should be closed to the total concentration, and the results obtained were between 81 and 120%. Both cultivars showed similar values for the bioaccessible fractions (~13.5 – 53% of the total content).

Resumo em Inglês:

Glasses are common trace evidence elements in crime scenes, and the analysis of this material can be essential for evaluating different criminal dynamics. This work aimed to analyze the possibility of differentiating and classifying windshield glass using multivariate analysis methods. Automotive glass fragments from different vehicle brands were evaluated according to internal and external faces. We have collected from literature EDXRF (Energy Dispersive X-ray Fluorescence) data for different oxides concentrations. These data were organized in a matrix with 56 samples and nine variables. We applied unsupervised (PCA, Principal Component Analysis) and supervised (SIMCA, Soft Interclass Modeling Classification Analogy) methods. We assessed the classification responses through ROC (Receiver Operating Characteristics). As a result, the PCA indicated the presence of two groups of glasses in three main components. SIMCA verified the unsupervised classification, and the distances and interclass residues parameters were adequate with no outliers. The ROC analysis indicated a sensitivity of 0.793, a specificity of 0.815, and an efficiency of 0.804 for predictions. We concluded that multivariate analysis was successful in discriminating between the internal and external faces of automotive glasses.

Resumo em Inglês:

Glyphosate is one of the most widely used herbicides in various crops. Based on the existing literature, this herbicide has carcinogenic characteristics, being able to be found in water courses, not only for its leaching in soils, but also in the effluents of the industries that produce it. Due to its negative impact on living beings, this work aims to investigate the applicability of the electrochemical treatment of a synthetic solution containing glyphosate with boron-doped diamond anode. Two electrochemical systems were tested (magnetic stirring and recirculation flow) for studying the applied current density (j = 30-200 mA cm-2), initial glyphosate concentration (250-850 mg L-1) and initial pH (3-9) as operating conditions. Best removal efficiencies were achieved at 100 mA cm-2, 850 mg L-1 of glyphosate and the natural effluent pH (≈5,0). The performance of the electrochemical systems was evaluated in terms of removal of chemical oxygen demand (COD) and energy requirements. After 120 min of treatment, comparing the magnetic stirring system to the recirculation it was verified that the first one is the most economically viable with an energy consumption of 56 kWh m-3. However, the results at both electrochemical systems are more efficient than those reported in the literature when the initial concentration, time and mass transport coefficient are considered.

Resumo em Inglês:

Brazil has the greatest plant diversity in the world. Many species exhibit a wide range of phytochemical compounds which can be exploited in food, agronomic, pharmacological and medicinal plant industries. Therefore, the chemical composition and in vitro bioactivities of volatile oil from Psidium firmum fresh leaves (PfVO) were investigated for the first time. GC-FID and GC-MS analyses revealed 28 compounds in PfVO. The major ones were α-selinene (20.8%), β-caryophyllene (16.5%) and nerolidol (10.4%). Results showed that PfVO affected the growth of Leishmania amazonensis promastigote forms in a dose-dependent manner; its IC50 value was 14.05 µg/mL. PfVO also exhibited antibacterial activity against Salmonella enteritidis, Yersinia enterocolitica, Staphylococcus aureus, Pseudomonas aeruginosa and Listeria monocytogenes; MIC values ranged from 25 μg/mL to 250 μg/mL. Moreover, PfVO promoted normal cell growth inhibition at 61.02 ± 1.97 µg/mL. Antiproliferative activity was observed against human tumor cell lines; IC50 values of MCF-7 cells, HeLa cells and M059J cells were 47.91 µg/mL, 73.78 µg/mL and 41.94 µg/mL, respectively. Results provided strong evidence of the promising potential of PfVO as a nature-based antileishmanial, antibacterial and antiproliferative agent.

Resumo em Inglês:

Electrophoresis is by far the most popular separation method implemented in microscale, most probably due to its instrumental simplicity, low cost and portability. Due to the increasing use of miniaturized electrophoretic systems, the study of fundamental aspects can improve the development of methodologies for several applications. One of the major challenges related to electrophoresis chips refers to the sample injection mode, in this way, this study presents a review on sample injection methods for microchip electrophoresis covering electrokinetic and hydrodynamic approaches, describing theoretic and instrumental aspects. Since the sample volume affects the analytical performance, the precise and reproducible control of the sample amount to be introduced into the separation channel is highly desirable to ensure reliable chemical analysis. Electrokinetic modes based on floating, pinched and gated protocols are presented and discussed providing an overview about the electrokinetic control of the sample through three methodologies. In the same way, hydrodynamic techniques including the use of microfabricated valves and pumps, syringe pumps, electronic micropipettes, rubber suction bulb and acupuncture needle are approached, thus expanding the view of hydrodynamic injectors based on classical and alternative methods.

Resumo em Inglês:

Pesticides are widely used worldwide in urban and rural environments. Since most pesticides are not selective for target species the concern about possible impacts on human health has increased for the workers exposed to these substances (occupational exposure) and for the general population (environmental exposure). Epidemiological studies, in vivo and in vitro have associated several diseases with pesticide exposure, such as cancer, diabetes, Parkinson’s, and others. Therefore, chemistry plays an important role in evaluation of external (food and drinking water) and internal (human biomonitoring) exposure to pesticides through of analytical methodologies, for instance, chromatography coupled with mass spectrometry, proving to be an important complement in the evaluation of risks of pesticides in human health.

Resumo em Inglês:

Heterocyclic compounds form an important and extensive group of organic substances. Among nitrogenous heterocyclic molecules, quinolines stand out for exhibiting attractive chemical and biological properties. These substances can be used as ligands, sensors, luminescent and agrochemical materials. In addition, quinoline-containing compounds can exhibit a wide spectrum of pharmacological properties, allowing their use in several approved drugs nowadays. Due to its importance, the synthesis of molecules containing this nucleus becomes a point of interest for synthetic chemists. In this way, several methodologies have been recently developed to prepare quinoline derivatives with high structural diversity. Such chemical transformations allow the chemical modification of these rings with high selectivity and tolerance to diverse functional groups and these properties have been conveniently used in the preparation of biologically active molecules containing this unit. Herein, we present a review of the main methodologies employed in the selective functionalization of quinolines in the last twenty years. In this context, a brief introduction addressing general synthetic and medicinal aspects related to the functionalization positions of the quinoline ring is presented. Several methodologies used in the functionalization of this moiety are discussed, as well relevant synthetic applications, both in the preparation and functionalization of substances of biological interest.

Resumo em Inglês:

In Brazil, wine-growing regions of high altitude have been evaluated for the cultivation of grapes destined for the production of quality wines. In this study the phenolic content, the volatile compounds profile and the in vitro antioxidant activity of samples produced in Água Doce, Campos Novos and Tangará were determined using spectrophotometric and chromatographic techniques. A total of 95 volatile compounds were identified in the samples analyzed, of which borneol is reported in Brazilian Merlot wines for the first time. The quantitative results showed that the most important volatile compounds for wine aroma were esters, fatty acids, 1-hexanol and 2-phenylethanol alcohols, and C13-norisoprenoids β-damascenone and α-ionone. The phenolic content observed was comparable to the results obtained for Merlot red wines from other regions in Brazil and in other countries. Also, the wine samples were effective in capturing the free radicals DPPH and ABTS.

Resumo em Inglês:

Neutralization with alkaline compounds is one of the most common adulterations in milk. The rosolic acid method is a classical test widely used in different countries for detection of neutralizers in milk. The official and a modified version were validated in a single laboratory validation process considering four adulterants: sodium bicarbonate(BI), sodium carbonate(CA), sodium hydroxide(HY) and sodium citrate(CI). The modified version, which presented better performance was selected for interlaboratory validation. In this process, samples of raw milk with acidities of 0.19% were neutralized with different concentrations of BI, CA, HY and C and tested for homogeneity and stability. Eight laboratories, which represented different sectors of the milk production chain, received and analysed these samples. The collaborative trial results confirmed the method performance, although sensitivity and precision were inferior to those obtained in the intralaboratory process, demonstrating its applications and limitations.

Resumo em Inglês:

Environmental Education arises in the context of understanding the urgency of the environmental crisis and the need to seek answers for its mitigation. The different perspectives of AE compete for the affirmation of notions of the world, of society, of social well-being, of work and of life. The research investigated the conceptions of Environmental Education (EA) present in the scope of the Federal Institutes, having as corpus the Pedagogical Course Project (PPC) of teacher training courses in chemistry offered in these institutions in 23 states and in the Federal District. The documents were analyzed, in their entire body, with the aid of Textual Discursive Analysis (ATD). The results demonstrate the predominance of a conservative environmental education, of an apolitical and biologizing character, in the analyzed documents, what can be reflected in the profile of the chemical educator to be formed in these institutions.

Resumo em Inglês:

We present the main concepts of nonlinear dynamics and thermodynamics of irreversible processes to introduce chemistry students to the topic of self-organized phenomena. This task is performed by theoretically describing the emergence of self-sustained oscillations, waves, and stationary patterns/Turing patterns in the Belousov-Zhabotinsky (BZ) reaction, through the Oregonator model. We carefully developed such a description, which resulted in long algebraic deductions and rich supplementary material. Considering that, we encourage the use of this material in undergraduate and graduate advanced physical chemistry classes.

Resumo em Inglês:

We herein present an experiment where the concentrations of tartrazine, sunset yellow and amaranth in samples containing these three food dyes are determined by system of equations (SE) and classical least squares (CLS) multivariate calibration methods using light absorption data. Firstly, concentrations are obtained by means of the well-known SE method, that is, by solving a set of three linear equations in which the Beer-Lambert’s proportionality coefficients are obtained from analytical curves. Then, it is shown that the CLS method is a natural extension to SE, with an arbitrarily large number of equations. Nevertheless, within the CLS method, the unknown coefficients are found using mixtures with known concentrations of each dye. In order to introduce the students to the basics of algorithms and numerical computations, data treatment is performed in a command-line fashion using a freely available software. Advantages of multivariate calibration models over univariate ones are made clear, and the performance of the CLS and SE methods is compared based on the root-mean-square error.

Resumo em Inglês:

Analytical Chemistry disciplines are present in the curriculum of several undergraduate courses. However, based on our experience, students not always are able to realize the association of the scientific concepts included in these disciplines with the social context and, specially, with their future field of work. In the present report, we used a case study about calcium supplementation by calcium carbonate and calcium chelate that included a science outreach activity, which was applied to students enrolled in three undergraduate courses: Pharmacy, Biomedicine, and Chemistry. We noticed that students not only got actively involved with the case, but also highlighted the importance of this activity, took the case beyond the classroom, and requested the inclusion of other similar activities in the discipline. Although different answers were presented for the case, the results obtained bring a positive impact on the instructors’ teaching practice and on the courses as a whole.

Resumo em Inglês:

In December 2019, the World Health Organization officially announced the discovery and fast spread of the new coronavirus disease (COVID-19), which is caused by the SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), discovered in Wuhan, China. Since the beginning of the pandemic, there has been a global search for the discovery of antiviral candidates capable of treating the infection caused by SARS-CoV-2. However, none of them has shown proved efficacy and low toxicity for an effective dose. In view of this, research with plants based in natural products has been highlighted by the low toxicity of its metabolites and reduced side effects, since plants have been used for millennia in the treatment of various diseases. In this review, we highlight some plant species and plant metabolites belonging to the structural class of phenolic, alkaloids and terpenes with promising antiviral potential against coronavirus that could be explored as potential candidates for drug prototypes in the treatment of COVID-19.