Resumo em Inglês:

Antimicrobial packaging is a promising type of active packaging, which has an antimicrobial agent incorporated into the polymer matrix, capable to eliminate or inhibit deteriorating and/or pathogenic microorganisms. The zinc compounds are antimicrobial agents commonly used to confer this feature. The objective of this work was to evaluate the antimicrobial activity of biodegradable Ecoflex® films with 1% and 2% (w/w) zinc oxide nanoparticles (ZnO NPs) and 1% and 2% (w/w) glass microparticles doped with ionic zinc (Zn MCs), against Staphylococcus aureus and Escherichia coli. The sample’s biodegradation in soil also were studied. Microbiological results showed that biodegradable polymeric films obtained were effective to inhibit and/or kill S. aureus and E. coli at the initial concentration of 104 CFU.mL-1 after 24 h of contact. When evaluated the biodegradation of the polymers containing the additives, the results showed that the addition of zinc compounds to the biodegradable polymer did not affect its biodegradability characteristic. The antimicrobial biodegradable films developed have potential application to the food packaging industry.

Resumo em Inglês:

The demand for new insecticides is increasing due to the appearance of insect populations that are resistant to currently used products. New insecticides should be efficient in controlling pests and present low toxicity to non-target organisms. Ascia monuste (Lepidoptera: Pieridae) is a destructive pest of cole vegetables, and the fire ant Solenopsis saevissima (Hymenoptera: Formicidae) is an important predator of these caterpillars in brassica crops. Tetragonisca angustula (Hymenoptera: Apidae) is very important in pollinating many plants and providing honey. Therefore, this study evaluated the toxicity of synthetic amides to A. monuste and its selectivity in favor of S. saevissima and T. angustula. The amides (2E,4E)-N-propylhexa-2,4-dienamide (3) and (2E, 4E)-N-butylhexa-2,4-dienamide (4) caused high (96 and 93%, respectively) and fast (48 h) mortality of A. monuste. The amides 3 and 4 were not harmful to the predator (mortality of 5.7% for amide 3 and 7.14% for amide 4) and were slightly harmful to the pollinator (mortality of 38.57% for amide 3 and 28.12% for amide 4). The amides 3 and 4 are promising, as insecticides, due to the high and rapid mortality of A. monuste with low and moderate toxicity to S. saevissima and T. angustula, respectively.

Resumo em Inglês:

In this work, nanocomposites formed from the natural polymer carboxymethylcellulose in combination with the polyacrylamide polymer and zeolite were obtained and characterized in relation to pesticide sorption capability. Hydrogels are three-dimensional network with large capacity of water or biological fluid adsorption. They have biocompatibility, biodegradability and non-toxicity properties, ensuring this class of polymers is widely used in different agriculture fields. Thus, the objective of the work was to investigate the process of paraquat sorption using a novel biodegradable nanocomposite. By mathematical modeling, it was possible to found that better models were the Freundlich-Langmuir isotherm and pseudosecond order kinetic, indicating that sorption is heterogeneous and similar to chemisorption process. Thus, such nanocomposites have great potential to be applied as an adsorbent material for removal of pesticides from contaminated water.

Resumo em Inglês:

Seed germination and plant cell cultures provide an alternative mean for producing secondary metabolites. The present study is an attempt to evaluate the effect of seed dark germination and some elicitors and precursors on the production of L-DOPA in Phaseolus vulgaris L. Callus cultured on Murashige and Skoog medium supplemented with various concentrations of different plant growth regulators. L-DOPA produced was quantified by UV-spectrophotometric method. In this study, a user-friendly, quick, and economical UV-spectrophotometric method was described to determine L-DOPA content in extracts from 33 biotypes of Phaseolus vulgaris L. The method is based on the nitrosation of L-DOPA to form a yellow solution and then formation of a red solution by adding base which is measurable at 470 nm. According to our statistical studies, this method showed high efficiency and selectivity for quantitative determination of L-DOPA in herbal extracts from dried plant seeds, dark-germinated seeds and callus cultures. L-DOPA content in dark-germinated seeds and suspension cultures increased significantly to approximately several-fold compared to the control. The implication from this study is that elicitor treatment and precursor feeding of Phaseolus vulgaris L. can significantly improve the parkinson’s relevant L-DOPA content.

Resumo em Inglês:

A novel sensing phase of polyurethane was predicted by quantum chemical calculations as capable of detecting toluene, with the experimental results revealing a limit of detection of 1.4 mg L-1 in the determination of toluene in water samples. The quantum chemical computational strategy was validated by assessing the impact of the polymer matrix sensing phases polyvinyl chloride (PVC), polydimethylsiloxane (PDMS), and polyisobutylene (PIB), as solvents, on the Gibbs energy of solvation of the organic contaminants toluene, benzene, chlorobenzene and ethylbenzene. Computational results for the set studied indicate that the limit of detection of contaminants for each polymeric matrix correlated well with the Gibbs energy of solvation. As such, the computational methodology was employed to assess the potential applicability of polyurethane matrices on the determination of toluene as a contaminant in water, with positive results. Analyzes were then carried out experimentally by mid-infrared spectroscopy. Finally, experiments revealed good regenerative capacity of polyurethane, further adding to the usefulness of the technique here advanced.

Resumo em Inglês:

One experimental strategy to prepare a nitrosyl metal complex is based on the acid-base conversion of NO2- into NO+. Here, we employed UV-vis absorption and FTIR spectroscopies to investigate the reaction of cis-[Ru(NO2)(bpy)2(imN)]PF6 with H3O+, which produced cis-[Ru(NO)(bpy)2(imN)](PF6)3 complex. Chromatographic studies were carried out and showed that immediately after nitrite complex was dissolved only one species was present with retention time(tR) of 6.81 minutes. Addition of H3O+ to nitrite complex led to the formation of one major peak with tR of 3.92 min supporting nitrosyl complex formation. The reaction of nitrosyl complex with cysteine was also monitored by HPLC and it showed clearly the formation and followed decrease of a peak at 3.38 minute with maximum absorption at 380 nm, consistent with an intermediate complex. Later, it was observed the appearance of a peak at 4.15 minute with absorption band at 470 nm. In contrast to the reaction with cysteine, methionine did not show the formation of any intermediate. The use of HPLC was an important tool to support mechanistic assumptions for nitrosyl reactions.

Resumo em Inglês:

A tea made with the leaves or stem bark of Bauhinia pulchella Benth (Fabaceae) is used in the treatment of diabetes. Ethanol (EEF) and aqueous (EAF) extracts were obtained from the leaves and the antioxidant and citotoxic activities were tested, as well as quantify the content of flavonoids and phenolic compounds (TPC). EEF and EAF showed similar profiles by HPLC, with the presence of three compounds. Column chromatography reverse phase (C18) and Sephadex LH-20, followed by semi preparative HPLC-C18 of EAF resulted in three flavonoids. Their structures were identified by 1H and 13C NMR as myricitrin (1), quercitrin (2) and afzelin (3). In assay of determination of reactive substances to thiobarbituric acid (TBARS), with DPPH, ABTS and nitric oxide (NO•) free radicals, EAF showed antioxidant potential higher than the EEF. This is the first report of the occurrence of the flavonoids 1-3, in the species B. pulchella. EEF and EAF were inactive in the cytotoxicity assays. In short, the polar extracts from the leaves of B. pulchella proved to be promising sources of biomolecules phenolic, with antioxidant potential, which may, in the future, be used as chemical markers for species and validation of therapeutic use.

Resumo em Inglês:

In order to produce bioactive derivatives of carvacrol and thymol, nine derivatives of each compound were prepared through modifications the phenolic hydroxyl group. The structures of compounds were confirmed by spectral data from MS, IR and NMR. Carvacrol, thymol and derivatives were submitted to the evaluation of the inhibition of the enzyme acetylcholinesterase, using a colorimetric method in which the inhibition of the enzyme is measured by coloration, and larvicidal activity against Aedes aegypti. Derivatives carvacryl acetate-1b and thymyl hexanoate-2b showed the best results for the inhibition of the acetylcholinesterase enzyme, and for the larvicidal activity the derivatives 1a, 1b, 1c, 3h, 2a, 2b, 2c and 4h showed positive results, emphasizing compound thymyl 4-methoxybenzoate-4h which showed LC50 values of 23.60 ppm, considered a very good result.

Resumo em Inglês:

Eight petroleum samples from Potiguar Basin were submitted for determination of saturated biomarkers by gas chromatography (fingerprint), liquid chromatography (saturates, aromatics, resins and asphaltenes), gas chromatography-mass spectrometry (GC-MS), nickel and vanadium by high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The geochemical parameters provided information on type of depositional paleoenvironment in which organic matter that gave rise to each oil sample and level of thermal maturation reached by generating rocks that make up the Potiguar Basin were deposited. The relationships between the stable isotopes of carbon (δ13C) and between Ni and V concentrations of each petroleum sample were also evaluated. The evaluations separated for oil samples into two distinct groups. Group 1 formed by samples P1, P2, P5 and P8, with characteristics of generating rock that was deposited in a marine hypersaline environment. Group 2 composed of samples P3, P4, P6 and P7 with freshwater lacustrine depositional paleoenvironment, which were elucidated through the geochemical parameters studied. The hierarchical cluster analysis was presented as promising chemometric tool for characterization of petroleum samples in the according to their origin of the generating rock by ratio parameters of hopane/sterane , tetracyclic polyiprenoids/diastereomers and diastereos R+S/cholestane R+S.

Resumo em Inglês:

The present study investigates the synthesis of agarose nanoparticles (ANPs) and its surface modification by galactose for the immobilization of β-galactosidase. Galactose modified ANPs retained 91% enzyme activity upon immobilization. Optimum pH (4.5) and temperature (50 ºC) remains unchanged after immobilization. However, immobilized enzyme retained greater catalytic activity against lower and higher, pH and temperature ranges. Immobilized β-galactosidase retained 89% biocatalytic activity even at 4% galactose concentration as compared to enzyme in solution, and exhibited 81% activity even after seventh repeated uses. Immobilized enzyme hydrolyzed greater amount of lactose at higher temperatures as compared to β-galactosidase in solution, thereby suggesting its potential application in obtaining lactose-free dairy products at large scale.

Resumo em Inglês:

Polyurethanes (PUs) are generating increasing interest in the biomedical field due to its characteristic properties. The objective of this article was review general properties of PUs and related with their biomedical applications, also to show the importance of the synthesis of PUs and how each one of the reagents used influences both mechanical properties and biological response of the designed medical devices. It is important to look for a correlation between mechanical properties and biological properties from the synthesis process of the PUs which allow to maintain the biocompatibility required by each medical device. In this work, the PUs are evaluated into three groups of applications: equipment and surgical instruments, temporary applications within the body, and permanent applications within the body. This review can show the broad field of use of PUs in biomedical applications.

Resumo em Inglês:

GlassPanacea is an efficient software tool that combines several attractive technical features with ease of use. Its configuration leads to the intuitive handling and learning with accurate results, providing the users with flexibility in the selection of suitable chemicals for the formulation of glassy, partially glassy or crystalline ceramic materials, as well as speed and accuracy in the calculation of the relative proportions of each chemical in a batch. The software runs directly from an executable file with multiplatform support. Hence, it can be used on different operating systems, such as Windows, Linux and Mac OS, without installation. One of its highlights is the user-friendly interface that enables immediate application, even for operators with little computer experience. This makes GlassPanacea a very valuable tool for students, researchers and engineers who work on the development of ceramic materials using different synthesis techniques, such as melting, solid-state reaction, sintering and sol-gel processing. The archive containing the software, information for use and logo can be downloaded, free of charge, from http://www.certev.ufscar.br/research-1/glasspanacea-glass-and-ceramic-formulation-software.

Resumo em Inglês:

The use of samples from students quotidian can get their attention for teaching contents to be presented. We have already presented a series of simple experiments demonstrating the use of flame atomic emission spectrometry in the determination of cations in samples present in our day life. Here sodium is determined in cachaça (sugar cane spirit), a very popular Brazilian drink, to demonstrate de effect of matrix composition and its physico-chemical properties in the volume of sample nebulized in a flame photometer and consequently in analytical signals by using different ethanol:water solvent mixtures for calibration.

Resumo em Inglês:

The present work aims to investigate the profile and motivation that led students to enroll in the undergraduate chemistry courses of the four São Paulo State University campuses. Case studies were carried out at each of the campuses and a comparative study was carried out in order to outline the theme in question. The quantitative data was analyzed by descriptive statistics and the qualitative data was analyzed by Content Analysis. It was found that the majority of the students are female aged between 17 and 19 years and came from public schools; they do not have jobs, and they are at an intermediate socioeconomic level. The vast majority of students chose the undergraduate degree in chemistry because of their interest in the large field of knowledge, along with the reputation and prestige of the university. It has also been identified that the graduates are led to teaching careers for essentially intrinsic motivations based on altruistic values; however, the majority does not choose to pursue a career in basic education. Faced with the scenario of possible “teacher blackout” in High Schools, these findings claim an urgent public educational policy that promotes an effective valuation of the teaching profession in Brazil.

Resumo em Inglês:

This article presents an experience of the use of the Problem Solving (PR) methodology with undergraduate students of the Licentiate Course in Chemistry of UFRGS, for the study of Ionic Bonding (LI). Salar de Uyuni salts were used to contextualize the problems employed. The Field Log records of the researchers and the presentations of the undergraduates show that the implemented didactic sequence favored conceptual learning, such as the relation between chemical bond theories and some properties of the materials, procedural learning, such as public argument, as reading and handling of different bibliographical reference sources and attitude learning, such as interpersonal relations among students and teachers during the different problem solving stages. Additionally, the results brought to evidence that, from the Problem Solving experience with the Ionic Bond contents, the future teachers were able to perceive work alternatives for their future classrooms.

Resumo em Inglês:

In the 21st century, medicinal chemists will face many challenges to improve the quality of life of populations. The challenges consist of emerging infectious (ex. bacterial, viral and parasite infections) and non-communicable diseases (ex. autoimmune, Alzheimer disease, Parkinson’s disease) that will require innovative technologies (ex. microfluidics, nanotechnology, biotechnology) to be fully understood and combated. In this work, we indicate trends, perspectives and opportunities related to drug discovery as well as highlight the tools and strategies that could be used in drug discovery of the 21st century.