Resumo em Inglês:

The insertion of functional groups in polymer compounds may facilitate their interaction with different drugs. PEG polymers are widely used for their low melting point, low toxicity, drug compatibility, and hydrophilicity. They are used as pharmaceutical excipients for the formulation of conventional or modified released drugs and are designed to be upgraded as drug-modulating controllers at specific sites in the body. Indomethacin has been used in the controlled release of drugs because it is a drug that have good interaction with different polymers. The drug is a non-steroidal anti-inflammatory drug used in the treatment of rheumatoid arthritis, osteoarthritis, spondylitis, and other disorders. In this work, PEG 4000 had its chain modified by organic reactions and their derivatives were emulsified to form microparticles using polyvinyl alcohol as an emulsifier. Posteriorly were also incorporated with indomethacin. The samples were characterized to prove the influence of indomethacin on the morphology and thermal behavior of this polymer. The controlled release was performed in the time from 0 to 240 min using the Ultraviolet Spectroscopy to quantify indomethacin released from the polymer matrix for these 4 hours. Releases over the time were satisfactory as concentrations increased over time, which we can conclude that the structural modification of PEG 4000 was beneficial in the release of the indomethacin drug.

Resumo em Inglês:

A chemical investigation of Anaxagorea dolichocarpa Sprague & Sandwith, a member of Annonaceae family, was carried out. The ethanolic extract from the roots of this plant led, by chromatography tecniches, to isolation of the new azaphenanthrene alkaloids dolichocarpine (1) and 9-methoxyeupolauramine (2), besides the known alkaloids eupolauramine (3), 3-methoxyeupolauridine (4), eupolauramine (5) and 4-methylsampangine (6). The structures of isolated compounds were established by 1D and 2D NMR, HRESIMS, tandem MSn and IR data. The cytotoxicity of compounds 1 - 5 was evaluated against HCT-116 (human colorectal carcinoma) and L929 (murine fibroblast) cell lines.

Resumo em Inglês:

The aim of this work was to develop a method using high performance liquid chromatography coupled with hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS) for the determination and speciation analysis of the inorganic and organic species of arsenic found most often in rice samples: As(V), As(III), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). The best chromatographic resolution was obtained using pH 6.2, a phosphate buffer mobile phase concentration of 20 mmol L-1 and flow rate of 0.57 mL min-1, HCl concentration of 5.55% (v/v), and NaBH4 concentration of 0.90% (w/v). The accuracy of the method was confirmed by the low relative error values obtained for analysis of a certified reference material (NIST 1568b): 6.63% (total inorganic As), 3.44% (DMA), 0% (MMA), and 0.53% (total As). In recovery tests, the proposed method achieved satisfactory recoveries in the range 86-110%.

Resumo em Inglês:

The production of xylitol from pentose-fermenting yeast is closely related to the amount of oxygen present in the culture medium. This study evaluated the effects of agitation and aeration in xylitol production using the yeast Starmerella meliponinorum FRP.09, previously isolated and selected due to its capacity to produce ethanol and xylitol from xylose. Fermentations were conducted in 125 mL flasks with 15 mL of culture medium and shaken at 150 rpm and 200 rpm without forced aeration and compared to fermentation in a static system. To assess the forced aeration, bioreactor was used with an air flow of 0.1 vvm and agitation of 100 rpm, 0.25 vvm / 150 rpm and 0.5 vvm / 200 rpm. Higher agitation and airflow significantly increased the xylose consumption. The yeast S. meliponinorum FRP.09 achieved the best xylitol yield of 0.6 g of xylitol per g of xylose consumed, when the fermentation was conducted with an air flow/rotation speed of 0.5 vvm / 200 rpm in bioreactor and 150 rpm in the fermentation flasks.

Resumo em Inglês:

Cellulose nanofibers (CNF) have been applied in composite systems due to the abundance of raw material, excellent mechanical and thermal properties. In this work, CNF was prepared from agroindustrial waste and used in specified amounts in polyvinyl alcohol (PVA) composites. The FTIR spectra of CNF, chemically purified cellulose (CPC) and Cassava Agro-industrial Waste (CAW) indicate the removal of hemicellulose and lignin. The increase of the crystallinity phase in CNF was observed, by XRD analysis and neither is observed the transition from cellulose I to II. Thermogravimetric analysis showed displacement that the initial degradation of the CNF over 43 °C degradation proceeds at single step. The chemical and dimensional homogeneity of CNF can be observed with the calculation of the crystalline phase content obtained by deconvoluted dTG curve and XRD spectra, obtaining 80% crystallinity by both techniques. SEM micrographs showed fibers with diameters of 22.30 ± 1.52 nm. An increase in the mechanical properties of PVA was observed with the addition of CNF. With 2.5% CNF in the PVA, the elastic module increased by approximately three times, with the addition of 10% CNF, a saturated system with poor mechanical properties was observed.

Resumo em Inglês:

This work describes the bioaccessibility in vitro simulated gastric digestion for levels of Zn, Ca, and P in milk and soybean extract samples. Total and dialyzed levels were determined by ICP OES. According to results of the dialyzed samples, it can be concluded that in 250 mL of milk (a glass) the body can be absorb about 1.2 ± 0.2 mg, 14.8 ± 1.2 mg, 4.5 ± 0.8 mg, 2.2 ± 0.4 mg and 4.9 ± 0.6 mg of Zn; 2079 ± 133 mg, 305 ± 4 mg, 2396 ± 16 mg, 2444 ± 54 mg, and 1527 ± 71 mg of Ca; and 2023 ± 275 mg, 811 ± 14 mg, 2688 ± 39 mg, 5089 ± 474 mg and 3467 ± 63 mg of P for raw sheep’s milk, soybean, raw cow’s milk, UHT goat’s milk, and UHT cow’s milk, respectively. These results correspond to approximately 45, 118, and 267% of diary human needed of Zn, Ca, and P, respectively. Accuracy was verified using CRM (NIST 8435) for total levels, and dialyzed samples were compared with FAAS, statistically evaluated by Student’s t-test. Results confirmed the methodology efficiency and allowed an estimate of the bioacessibility of nutrients.

Resumo em Inglês:

Mid-Infrared absorption spectroscopy associate with the Partial Least Squares regression is the official method to monitor Brazilian commercial diesel quality. This method, however, uses solvents and a large number of samples for the construction of the calibration curves, which generates waste and increases the time needed for the analysis. In order to develop a non-destructive method, being possible to recover the sample after its quantification, decrease the quantity of samples and make use of a single calibration curve, in this study we used the oilseed crambe, which is not used in human food, for the methyl biodiesel production and PLS analysis for their content determination in mixtures with diesel at a concentration range of 1.00 to 30.00 (% v/v). The global model for crambe methyl biodiesel obatined RMSEC = 0.26 (% v/v), RMSECV = 0.35 (% v/v) and RMSEP = 0.41 (% v/v). Complementary, variable selection method iPLS was applied in the global model in order to reduce the spectral range required to regression construction and to improve the RMSEP, RMSECV and RMSEC values.

Resumo em Inglês:

Starch is a promising source of biopolymers and the incorporation of essential oils (EOs) into it can improve some biological properties of films. This study aimed at developing and characterizing barrier, biodegradability and optical properties of biopolymeric films made from arrowroot starch and at incorporating EOs from Piper aduncum leaves and inflorescences in order to analyze their antifungal activity against Rhizopus microsporus and Colletotrichum gloeosporioides. The casting method was used for developing arrowroot starch films and incorporating EOs into them. Resulting films exhibited satisfactory barrier properties, low water vapor permeability (WVP), transparency and good barrier property against UV-vis light, besides being 100% biodegradable. In addition, films enriched with EOs at 0.75% and 1.0% revealed promising antifungal activity. Results showed, for the first time, that arrowroot starch enriched with EOs from P. aduncum can potentially be used as an active film due to its excellent physicochemical properties and antimicrobial activity.

Resumo em Português:

In this study was evaluated the influence of the extraction factors on the extract’s properties to improve the recovery of high concentrations of the phytochemicals important for the biological activities from pods of Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz. The extracts were obtained by turbo-extraction and a factorial design 32 was used to study the importance of the drug amount (5, 10 or 15 g) and the solvent (Ethanol 40, 60 or 80%, v/v) on the variables of response, and the optimization was performed by Response Surface Methodology (RSM) and Desirability profile. Mathematical models were fitted according to experimental data and the validated equations were used to generate RSM for each dependent variable (dry residue; total polyphenol content; content of gallic acid and ellagic acid; and, efficiency of extraction). The factors studied within the applied experimental field presented different influence profiles for the responses, and significant interactions between linear and quadratic terms. The statistical analysis showed high R2 > 0.99. The RSM and Desirability (> 0.95) allowed to show that the optimum conditions to produce extractive solutions of Libidibia ferrea with high efficiency for ellagic acid and gallic acid were 15 g and ethanol 40%.

Resumo em Inglês:

A novel electrochemiluminescence (ECL) biosensor for the determination of lipopolysaccharide (LPS), a biomarker of endotoxemia, was designed. The nanoprobe (Ru1@SiO2-peptide) with a specific peptide (CIGKLHSAGK) labeled with a carboxyl functionalized Ru@SiO2 (Ru1@SiO2) was prepared by the acylation reaction. The ECL peptide biosensor was obtained by the strong gold-sulfur bond between Au on the gold electrode (AuE) surface and thiol group in the peptide. In the present of LPS, the peptide on the ECL biosensor can capture effectively LPS and the LPS/peptide/AuE was fabricated. When the Ru1@SiO2-peptide nanoprobe was bound, a sandwich compound of Ru1@SiO2-peptide/LPS/peptide was formed, and Ru(bpy)32+, in the sandwich compound, will do the ECL performance. The effective ECL amplification of Ru1@SiO2 exhibited excellent analytical performance to LPS with a wide detection linear range of 1.0~500 ng mL-1 and the detection limit was 0.3 ng mL-1. The biosensor could provide an evaluate of LPS expression on the bacteria surface and guide a new path to the clinical analysis of LPS related diseases.

Resumo em Inglês:

The synthesis, characterization, cytotoxicity and antitumor activity of platinum(II) complexes coordinated to O-glycoside and analogous is reported. Through the acute toxicity tests, it was possible to fit the complexes into categories according to the OECD protocol. The cis-[PtCl2(C6H14S2O2)-κ2S] complex was classified in category 3 and the cis-[PtCl2(C26H38O12S2)-κ2S] complex was classified in category 4. This result demonstrates the lower toxicity achieved by the glycoside in comparison with its analogous system. Evaluations of tumor masses extracted from mice inoculated with Ehrlich carcinoma demonstrated percent inhibition similar to cisplatin and synthesized platinum complexes. Cisplatin showed 59% inhibition, while cis-[PtCl2(C6H14S2O2)-κ2S] and cis-[PtCl2(C26H38O12S2)-κ2S] complexes presented 57% and 59%, respectively. Although the glycosidic compounds exhibit tumor activity, reported in the literature, the presence of platinum ion was shown to be determinant for antitumor action according with the compounds tested, since the glycosidic ligand presented tumor inhibition of only 38%, with a similar antitumor activity in relation to cisplatin.

Resumo em Inglês:

Lead is environmental pollutant that even in low trace is harmful for human health and wildlife. In this study we presented a colorimetric method for determination of Pb2+ in water by aggregation of silver nanoparticles capped citrate in the presence of deferoxamine as chelating agent. Silver nanoparticles were prepared by reduction of AgNO3 with NaBH4. In the presence of Pb2+, mixture of silver nanoparticles capped citrate and deferoxamine aggregated and color of solution changed from light yellow to violet that depends on Pb2+ concentration. As a result of aggregation, local surface plasmon resonance (LSPR) band of silver nanoparticles around 440 nm decreases and a new band appears at 580 nm that depend on Pb2+ concentration. Under optimized conditions, linear relation of concentration of Pb2+ and absorbance ratio (A580/A440), was from 0.19 to 1.29 µmol L-1 and limit of detection of 0.056 µmol L-1 was found. Control experiments with the addition of 10 other metal ions (Ni2+, Cu2+, Ca2+, Al3+, Co2+, K+, Ba2+, Zn2+, Mg2+, Hg2+) did not result in a distinct change in the color or in the absorption spectra. This approach was successfully tested for determination of Pb2+ in well and tap water.

Resumo em Inglês:

Diacetonediperoxide (DADP) derivatives were investigated with density functional theory (DFT) methods at the DFT-B3LYP and M06-2X/6-311++G (d, p) levels and were also compared with other multi-peroxidic compounds. The investigated derivatives were 3,6-dimethyl-3,6-diamine-1,2,4,5-tetraoxane (DADPNH2), 3,6-dimethyl-3,6-dinitro-1,2,4,5-tetraoxane (DADPNO2), and 3,6-dimethyl-3,6-bis(trifluoromethyl)-1,2,4,5-tetraoxane (DADP3F). The investigations were focused on detonation performance and stability which were determined according to geometrical and electronic structure. The results of the simulation revealed that DADP derivatives are less sensitive than some other organic peroxidic compounds. In addition, detonation performance, including explosion heat (Q), detonation velocity (D), and detonation pressure (P), was estimated according to density and heat of formation using EXPLO 5 software. The results revealed that DADPNO2 has better detonation performance (Q = 5543 kJ kg-1, P = 23.7 GPa, D = 7631 m s-1) compared with traditional explosive 2,4,6-trinitrotoluene (TNT; Q = 5418 kJ kg-1, P = 19.0 GPa, D = 6950 m s-1). Therefore, it is a novel candidate for use as an energetic material.

Resumo em Inglês:

Biocatalysis is now a mature field, both in the laboratory and industrial scale. This approach counts on enzyme high selectivity, biodegradability, elegant control over the outcome of reaction conditions and as a possible solution to address some challenges in Green Chemistry faced by synthetic organic chemists. However, many wild-type ready-to-use enzymes were not designed to accommodate the organic substrates needed by today’s demands. Or they do not fit a predefined optimum process condition or even, useful reactions are not accessible because there is no enzyme counterpart for metallo- and organocatalysts. This review will give a brief introduction on the protein engineering tools (directed evolution, rational design, and semi-rational design) and will focus on directed evolution of enzymes, their impact in chemistry with examples from production of commodity chemicals to pharmaceutical intermediates and its potential as a tool to achieve greener chemistry criteria will be discussed.

Resumo em Inglês:

Helicteres genus, Malvaceae, has pantropical distribution, encompasses about 60 species, 31 of them found in Brazil. Species belonging to this genus are used for treatment of various diseases and aroused scientific interest in search for bioactive compounds present in these plants. In this context, this review aims to provide a complete and concise overview of scientific advances in phytochemical and pharmacological studies of these species and their use by folk medicine. The presented data were collected from scientific databases, ‘Web of Science’, ‘Scifinder’, ‘Pubmed’, ‘Sciencedirect’, and ‘Google Scholar’, using the keyword ‘Helicteres’. The species H. isora and H. angustifolia, found in Asia, are the most explored scientifically, whereas studies of species of this genus found in Americas are still rare, being possible to highlight studies carried out in Brazil with H. velutina and H. eichleri. About 149 compounds were isolated and characterized in the genus, being emphasized terpenoids, flavonoids and lignoids. These species have demonstrated various pharmacological properties in vitro and in vivo, incluinding insecticide, antidiabetic, antitumor and hepatoprotective activities. The presented data show the importance of studies carried out isolating bioactive compounds from this genus that may be used in several diseases’ treatment or/as prototypes to development of new drugs.

Resumo em Inglês:

Molecular dynamics techniques are increasingly being used for material science studies, being a theoretical approach based on molecular mechanics studies. GROMACS is a free software that allows the development of simulations of various types of molecules, from biological molecules to inorganic structures associated with the area of materials, requiring the system parameterization according to the force fields used in the simulation. ClayFF is a force field used for crystalline clay structures and has been applied in several articles published in scientific journals. The objective of this work was to present a didactic approach to the implementation of ClayFF in GROMACS and the force field was used to simulate a kaolinite structure as an example, demonstrating the implementation for students and researchers in the field.

Resumo em Inglês:

Nanotechnologies and nanomaterials are very current and interesting topics and can be used as interdisciplinary tools in education. They can be used to work in a practical and interesting way with lots of subjects. In chemistry teaching it can be particularly important to consolidate the nanomaterials, nanotechnology and characterization teaching. Among the nanomaterials, quantum dots (QDs) can be highlighted due to their interesting optical and electronical properties. Some of the topics that can be discussed related to them are the nanoparticles synthesis, spectroscopies and optical characterization, X-ray diffractometry and structural characterization, surface ligands, semiconductor materials, electronic transition, solid crystalline structure, colloidal synthesis, among many other subjects. The application of the experiment of synthesis and characterization of environmentally friendly quantum dots to students of the discipline “Solid State Chemistry” of the chemistry undergraduate course, allowed the contact of students with materials of great technological interest. Being a material widely studied by various research groups around the world. The experiment proved to be an interesting way to introduce students to a material of great technological interest, in a simple and accessible way. It aroused the interest of the students while allowing the practical application of the acquired knowledge.

Resumo em Inglês:

Brazil’s gender gaps numbers are scarce in the field of chemistry. Thus, the motivation of this work is to perform a data survey considering all levels of the academic career and per Brazilian region. The data collected shows a general trend observed in all scenarios, whereas the higher the career level the lower the number of women inserted. Women dominate in the early stages of the scientific careers, such as postgraduate programs (52%) but become minority (42%) when they get positions as university professors. The disparity is higher at positions of great recognition, e.g., member of the Brazilian Academy of Science (18%) or the highest level of CNPQ research productivity fellowship “1A” (12%). Other career indicators such as research grants approval, authorship in recognized international journals and in highly cited articles authored by Brazilian scientists, show low female representativity. Leadership positions in scientific societies and funding agencies are alarming (6%), where many organizations never had a woman president. The world needs more female references in science and surely Brazil has many great women in the field of chemistry that deserve recognition. The present study sheds light to the awareness of the Brazilian scenario.