Resumo em Inglês:

Alogliptin (ALG) benzoate is an oral hypoglycemic drug that works as a DPP-4 inhibitor to prevent incretin degradation. Forced stability studies use high temperatures to decompose drugs and estimate their behavior at low temperatures. We aimed to evaluate the thermal stability of ALG using two techniques: isothermal thermogravimetry (TGA) and degradation in an oven followed by liquid chromatography (LC-PDA) analysis. ALG was subjected to 150, 155, 160, 165, and 170 °C up to 10% of mass loss in isothermal TGA. In the oven, the drug was submitted to 130, 140, 150, 155, 160, and 170 °C. Kinetic parameters were calculated with the Arrhenius model. ALG followed zero-order kinetics, in which the degradation rate did not depend on reagent concentration. Activation energy ranged from 31.0 to 35.9 kcal mol-1. The degraded drug was less toxic in a cytotoxicity assay in CRIB cells than the undegraded drug. The TGA method is faster and more practical than the oven followed by LC-PDA, and the data present a correlation. Here we described the kinetic parameters of ALG degradation, improving the knowledge about the drug and assisting in developing new formulations from the drug.

Resumo em Inglês:

Textbooks show that in cis-1,3-disubstituted cyclohexane molecule, the conformer with the substituents in the diaxial positions is higher in energy and hence, it presents a low population in the conformational equilibrium. The diaxial conformer is destabilized by the repulsion between the substituent groups and the axial hydrogen atoms on the same side of the ring. This interaction is known as the 1,3-diaxial interaction. In this study, the solvent effect on the conformational equilibria of cis-3-N-ethylaminocyclohexanol (cis-3-EACOL) and cis-3-N,N-diethylaminocyclohexanol (cis-3-DEACOL) has been assessed through the spin-spin coupling constant (3JHH). The results show that the diaxial conformation of cis-3-EACOL decreases from 92% in CCl4 (∆Gee−aa = 1.48 kcal mol−1) to 10% in DMSO-d6 (∆Gee−aa = −1.31 kcal mol−1). For cis-3-DEACOL the diaxial conformer decreased from 36% in CCl4 (∆Gee−aa = −0.33 kcal mol−1) to 7% in Pyridine-d5 (∆Gee−aa = −1.55 kcal mol−1). The stabilization of the diaxial conformer in nonpolar solvents takes place due to the O-H···N intramolecular hydrogen bond, which overcomes the 1,3-diaxial steric interactions.

Resumo em Inglês:

Brazil is the largest coffee producer in the world, and together with the millions of tons produced, millions of tons of residues are also generated. The generated residues are a source of environmental contamination depending on the chosen processing route. One of the main applications of food industry waste is in the production of raw materials to produce edible films and coatings. Coffee mucilage is a pectin-rich liquid residue from the coffee sector that can be used in the production of value-added products. Given this, the objective of this work was to characterize and evaluate the potential of functional and technological properties of coffee mucilage and your applicability in the production of edible films. The filmogenic mixture was obtained by casting from 10% (w/v) lyophilized coffee mucilage and solvent (water). The films produced from the coffee mucilage presented good homogeneity, continuity (absence of ruptures or fragile regions), flexibility, ease of detachment of the support and handling, without the need to add adjuvant to its formation. In addition, they presented uniformity in thickness, high light barrier and medium water vapor barrier. Thus, it can be concluded that mucilage is a potential product to be used in the cosmetic, pharmaceutical and food industries.

Resumo em Inglês:

Olive samples were subjected to the salting process in brine containing 1196 mol m−3 of NaCl and 402 mol m−3 of KCl. Samples were collected during 60 h and salt concentration values were determined. With the finite element method (FEM) and the minimization of the errors percentage between the simulated and experimental values, the mass transfer coefficients in the film (hm) were obtained, being 1.0072 × 10−8 and 1.2499 × 10−8 for NaCl and KCl, respectively. The salts concentration at the olive/brine interface was simulated by FEM and analyzed via SOFM. A network with 4 × 4 topology and 10000 training epochs was used. It was observed that the influence of the stationary film formed on the surface of the olives during the salting process depends on the position, the salt involved in the diffusion and that the concentration of the salts, at each point, varies according to the immersion time.

Resumo em Inglês:

We investigated the effect of both electron donating group and e//lectron withdrawing group on biological activity of pyrimidine-based compounds as metalloproteinase-7 inhibitors and predicting a library of drug-like compounds with potent cytotoxicity using in silico approach. The selected compounds were optimized and subjected to both docking as well as absorption, distribution, metabolism, excretion and toxicity (ADMET) analyzes. We observed that the addition of electron withdrawing group (–CF3) to the predicted pyrimidine-based compound induced a radical improvement in the hydrogen bond strength with Leu181 and Ala182 in matrix metalloproteinase-7. Also, communal orientation of 2-mercapto-4-(3-(trifluoromethyl)phenyl)-6-((4-(trifluoromethyl)phenyl)amino) pyrimidine-5-carbonitrile (PC10) and matrix metalloproteinase-7 showed improved binding tendency with calculated binding affinity value of -10.2 kcal mol−1 than other studied compounds. Our findings may open door for the design and development of library of efficient pyrimidine-based drug-like compounds as potential anti-cancer agents.

Resumo em Português:

RECENT ADVANCES IN THE ELECTROPHILIC ADDITION OF CHALCOGEN ATOMS TO ALKENES. Organochalcogen compounds (containing S, Se and Te) are interesting from biological point of view, but also in their use as intermediates in obtaining complex molecules or even for exploring their properties. In this way, chalcogen electrophiles are very powerful reactants and can be added to alkenes to form a three-membered intermediate called chalcogeniranium ion. This specie reacts with different nucleophiles to undergo a series of molecules containing chalcogens with interesting properties. The addition of electrophiles from chalcogens to alkenes is one of the oldest reactions in the field of the chemistry of these compounds and because of this many modifications have already been explored. Among them, methodologies that make use of transition metals to the most recent ones exploring aspects of Green Chemistry. This review starts with an overview of the background involved in electrophilic addition reactions of organochalcogenic compounds in alkenes and then, describes the recent methodologies leading to the synthesis of useful molecules and hoping that it will be beneficial to provoke further research and reflection in this field.

Resumo em Inglês:

Alcohol residues in biodiesel can be present even after the purification steps. It diminishes the flash point, lubricity and cetane number. The standard technique to quantify residual alcohol in biodiesel is the FID-GC with headspace sampling. NMR, although underused for quantitative analyses, requires no special sample preparation, and consumes low volume of solvent. In this work, methodologies for the residual methanol and ethanol contents in soy biodiesel by 1H-NMR in a 9.4 T (400 MHz) spectrometer by standard addition were developed and validated. Quantification limits were found equal to 0.07 and 0.08% respectively, so more than twice lower than the maximum level acceptable, which is 0.2%. Accuracy and precision were considered suitable for the alcohol content around the specification limit.

Resumo em Português:

DETAILED GUIDE TO OWN ASSEMBLY OF 3D PRINTERS. In recent years, there has been an increase in the use of 3D printing for the manufacture of three-dimensional objects. Thus, it is clear that 3D printers have presented as a tool with high potential for applications in several fields, including chemistry. However, despite its popularity, it is notable that some 3D printers have a relatively high cost, in addition to not favoring optimizations or repairs, making users dependent on the manufacturers of such tools. Therefore, this article aims to present, particularly to the chemistry community, a detailed guide for assembling a low-cost FDM-type 3D printer with good performance. Consequently, we hope that this guide can contribute to increasing the 3D printing popularization in the field of chemistry because of the various possibilities of applications in this area.

Resumo em Português:

THE BIOCHEMISTRY BEHIND COVID-19: WEBQUEST DEVELOPMENT AND APPLICATION FOR EMERGENCY REMOTE TEACHING. WebQuests are inquiry-oriented activities structured in such a way that almost all resources used come from the web. The present study aims to investigate to what extent a WebQuest focusing on Biochemistry and COVID-19 can be used as an instructive tool to enhance undergraduate students’ media and information literacy (MIL). Students’ opinions on the use of the WebQuest were also discussed. The WebQuest was implemented in a BSc in Physical and Biomolecular Sciences course in the context of the COVID-19 pandemic. Based on the results of this study, the WebQuest has improved the MIL competence of students and motivated them towards learning Biochemistry.

Resumo em Português:

AN ANALYSIS OF THE PROCESS OF DEVELOPING QUESTIONS PRODUCED BY CHEMISTRY STUDENTS IN A TEACHING PROGRAM BASED ON SCIENTIFIC COMMUNICATION LITERATURE. The objective of the present investigation was to evaluate the use of scientific dissemination literature (SDL) in the process of formulating questions developed by chemistry students in a Teaching Program in Chemistry. To this end, the book entitled The Disappearing Spoon was analyzed in terms of categories referring to format and content, while the 18 questions produced by these students about the chapters read were analyzed in terms of presupposition and request. The investigation was carried out with 16 undergraduates who were taking a theoretical course on “Introduction to Chemistry”, as part of the Teaching Program in Chemistry. According to the analysis carried out, some particularities of format, such as the scarcity of visual resources, the autonomous structure of the chapters and the language, may have influenced the elaborated presentations. It is interesting to note that almost half of the questions produced were of an investigative nature, demonstrating the potential of SDL to stimulate high cognitive skills. In addition, the questions with investigative requests were mostly opinion questions, which may have been motivated by characteristics of the text read, such as the content with a controversial approach used by the author, when reporting on some aspects of scientific activity.