Resumo em Inglês:

Polymer gel systems find applications in diverse areas, ranging from contact lenses to agriculture and oil production. In general, polyacrylamide (PAM) gels are produced by reaction with metallic (low temperatures) and organic (high temperatures) crosslinking agents. In this paper, given crescent environmental concerns, polyethyleneimine (PEI), an organic reactant, was chosen as the crosslinker of PAM, at 65 ºC. The effects of using a solution of water/glycerol as the solvent for preparing the gels and the addition of diethylenetriamine (DETA), a n-alkylamine, on the gelation kinetics and gel stability were evaluated. The data presented in this paper indicate that the solvent mixture provided a more controlled gelling behavior by delaying the gelation time. Also, diethylenetriamine acted both as an efficient anti-syneresis agent, improving gel stability, and by delaying the progress of gel strength.

Resumo em Inglês:

This research aims to study fluconazole (FNZ)-solvent interactions in pure solvents through theoretical and experimental solvatochromism. This study showed a bathochromic shift as the polarity of the solvent increases, where the excited state of FNZ is of higher polarity and lower energy than that of the ground state. The multiparametric statistical analysis highlighted solvent polarizability, dispersion, and electronic induction as solvent parameters of great importance, with the basicity of solvent and hydrogen bond acceptor capacity as having certain relevance. The thermochromic effect was also determined by exposing the three pKa values of FNZ. In conclusion, this study shows the importance of the π-π stacking interaction of the FNZ dihalogenated phenyl ring, the solvent basicity for the hydroxyl group, and its acidity for the N4’ of one of the triazoles stand out, as well as the acid-base equilibria involving the -OH group and the two N4’.

Resumo em Inglês:

Toads of the Rhinella genus have a pair of paratoid glands that store biological secretions of high toxicity and varied chemical composition, rich in biologically active compounds. The present work aimed to carry out the investigation of the metabolomic profile and evaluation of the biological potential of the secretion paratoid glands (PGS) from Rhinella granulosa. The paratoid secretion was collected in the Piauí state (Brazil), extracted with methanol and the extract was analyzed by ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry. Fifty chemical constituents were identified. The extract showed cytotoxicity against tumor cell lines of the central nervous system (half maximal inhibitory concentration (IC50) = 1.9 µg mL-1) and prostate (IC50 = 1.6 µg mL-1), unsatisfactory antimicrobial potential (minimal inhibitory concentration (MIC) > 312 µg mL-1) and inhibited the enzyme acetylcholinesterase (IC50 = 5.119 mg mL-1). The results presented relevant information about the PGS and contributed to the understanding of the metabolomic and biological potential of R. granulosa.

Resumo em Inglês:

Chloroquine is a drug belonging to the aminoquinoline family that is widely used for treating diseases such as lupus, cancer, and malaria. In this sense, the present work describes the development of a simple method based on electrogenerated chemiluminescence (ECL) and a screen-printed carbon electrode (SPE) modified with carbon black for chloroquine determination. The carbon black modified SPE was characterized by scanning electron microscopy, Raman spectroscopy, cyclic voltammetry and linear sweep voltammetry to obtain the ECL-potential curves. The ECL method is based on the chemiluminescence resulting from the interaction between chloroquine and the tris(2’2-bipyridyl) ruthenium(II) complex. Under optimized experimental conditions, the method showed a wide linear working range between 0.5 and 500 µmol L-1. The method presented good precision and accuracy in drug samples used in the treatment of malaria and artificial urine sample, showing recovery values from 100 to 103% and 99 to 103%, respectively.

Resumo em Inglês:

Ergosterol peroxide (EP) has been extensively studied for its antitumor activities. However, its further development has been restricted due to its limited intracellular accumulation and poor aqueous solubility. In this study, a novel triphenylphosphonium cation (TPP+) moiety was coupled to ergosterol peroxide to precisely target it at tumor cell mitochondria. The synthesized Mito-EP derivatives Mito-EP-3a-3d displayed stronger cytotoxicity than the EP parent and exhibited selectively cytotoxic effects between cancer cells and normal gastric epithelial (GES-1) cells. The most potent compound, Mito-EP-3b, was 9.7-fold more efficacious than ergosterol peroxide in the MCF-7 (breast cancer) cell line and showed good selectivity (SI = IC50GES-1/IC50MCF-7 = 4.04, IC50: concentrations to inhibit 50% of cell growth). Furthermore, Mito-EP-3b was able to decrease the mitochondrial membrane potential and induced reactive oxygen species production, accompanied by activating the expression of cytochrome c and Bax, while Bcl-2 expression was suppressed. The molecular mechanism may refer to the mitochondrial apoptotic pathway. Overall, the above results incentivize the further study of Mito EP-3b derivatives as potent anticancer agents.

Resumo em Inglês:

Petroleum reserves available worldwide are geologically based mainly on sedimentary and carbonate rocks, and the reservoir performance depends on the intrinsic properties of each rock and their response to changes in wettability. Recently, the change in wettability with low-salinity brine has been used to improve the oil recovery, which is an environmentally friendly and low investment, but there is no unanimity about the mechanisms of oil recovery process. Therefore, the aim of this study is to investigate the process involved in the wettability associated with interactions between the surface of powdered reservoir rock samples and the surrounding fluids. The reservoir rock surface (sandstone, calcite and dolomite) was evaluated under three different conditions. The total amount of adsorbed oil on aged samples was twice as high in carbonate rocks as in sandstone. The thermal gravimetric analysis (TGA) for the desorption steps of the organic fraction on dolomite and calcite indicates that the treatment under high brine concentration favored the oil desorption and the opposite result was observed for sandstone. This behavior suggests that carbonate rocks adsorb more strongly the organic phase compared to sandstone.

Resumo em Inglês:

In the present study, we tested the proof of concept that mobil mesoporous silica nanoparticle composition of matter (MCM) No. 48 doped with trivalent europium (nanoMCM48:Eu3+) administered systemically intravenously can act as a suitable vehicle to deliver neural cells to the brain of healthy adult Swiss mice without causing tissue damage. Moreover, we also tested the ability of this nanoparticle to release molecules in vitro, using as drug models caffeine or nicotine in phosphate buffer solution with pH 7.4 adequate to intra and extra-celular medium of the brain. The caffeine and nicotine adsorbed nanoparticles (CAF@MCM48:Eu3+ and NIC@MCM48:Eu3+) were observed in the parenchyma of the cerebral cortex and diffusely dispersed in the cellular cytoplasm. Statistical analysis using multivariate partner recognition methods indicated that there was no sign of cell damage, as it was characterized by chromatin condensation, nuclear condensation, or fragmentation. The characterization of nanoMCM48:Eu3+ as particle size, luminescent properties and release of active components were analyzed. The CAF@MCM48:Eu3+ and NIC@MCM48:Eu3+ nanoparticles were observed in the cerebral cortex parenchyma and diffusely dispersed in the cell cytoplasm, and the release of active components was analyzed. Therefore, the studies showed that mesoporous silica nanoparticles administered systemically via intravenous tissue can act as a suitable vehicle for neural cells in the brain of healthy mice without causing damage.

Resumo em Inglês:

Wavepress is a signal processing software that has a simple and friendly interface that can be used by researchers, professors and students. The program uses the wavelet transform, which is a signal processing tool, being used to handle a signal in the time-scale space. In this way, the program can be used for signal processing capable of reducing, without losing important information, the amount of information. Thus, it is possible to obtain graphs and tables to explore the results in a comprehensive and satisfying way. In this work, the main features of Wavepress are explored with applications in computational chemistry, and drug design, all examples are illustrated with graphs and tables got with Wavepress.

Resumo em Inglês:

A novel class of potential herbicides, 3-indolylglycines, was synthesized using an effective, green and rapid approach via multicomponent reaction (aza-Friedel-Crafts) between indoles, aldehydes and anilines in a water/sodium dodecyl sulfate system. The main advantages of this methodology are ease of handling, scalable to gram scale and a metal-free approach. The reaction is compatible with a variety of functional groups, obtaining the desired products in moderate to excellent yields. The biological activity of the 3-indolylglycines was evaluated, and it was found that these compounds interfere with the germination and radicle growth of Lactuca sativa, mainly the compound 4k.

Resumo em Inglês:

The search for compounds with affinity for both mu-opioid receptor (MOR) and sigma-1 receptor (σ1R) is one of the innovative directions to develop painkillers with reduced side effects. Additionally, triazole scaffolds have been extensively explored in the last two decades in medicinal chemistry. In this context, we synthesized a series of new triazole fentanyl derivatives and evaluated their affinity for both MOR and σ1R. The binding affinity of the compounds for human MOR was determined in competitive radioligand binding assays, using fentanyl as standard. For the assays with σ1R, a σ1R agonist (SKF10047) was employed. The most active analogue was 6d which moderately binds to MOR with half-maximal inhibitory concentrations (IC50) = 1.9 µM and to σ1R with IC50 = 6.9 µM. Molecular docking calculations were carried out, providing a structural elucidation for the observed values of affinity. Absorption, distribution, metabolism, and excretion toxicity (ADMET) parameters for the new compounds were simulated with the SwissADME tool.

Resumo em Inglês:

The objective of this paper was to evaluate the kinetics of the hydrolysis of soybean oil by the action of the Lipozyme® TL IM enzyme varying the operational conditions of molar ratio water/oil (9:1-60:1) and temperature (40-64 °C). To describe the experimental data, a mathematical model based on the kinetic mechanism of Ping-Pong Bi Bi (PPBB) was proposed, in which the following steps were not considered formation of the complex enzyme/oil substrate, and formation of the acylated enzyme/oil substrate complex. The results of enzymatic hydrolysis of soybean oil indicated a yield in free fatty acids of 76% at the molar ratio of 46:1 and temperature of 52 °C. Furthermore, based on the values of the determination coefficient and root mean square error, the mathematical model based on the kinetic mechanism of PPBB showed good agreement with the experimental data in a relatively wide temperature range. Thus, it can be a useful tool for the optimization and assessment of the mechanisms of enzymatic hydrolysis of vegetable oil.

Resumo em Inglês:

A theoretical investigation of the 1,2-additon and 1,4-addition reactions of benzylamine to crotonaldehyde in toluene solution is reported in this study, including the effect of trace amounts of acetic acid (AcOH) and methanesulfonic acid (CH3SO2OH). We have determined the reaction free energy profile and performed a detailed microkinetic analysis. Our results point out that this reaction system needs catalysis to take place and it was found that CH3SO2OH is a powerful catalyst, outperforming AcOH in lowering the free energy barrier for the 1,2-addition reaction, which leads to the formation of α,β-unsaturated imine. On the other hand, the 1,4-addition reaction has the direct nucleophilic attack of benzylamine to the β-carbon of s-cis conformation of crotonaldehyde as the rate-determining step, corresponding to slow kinetics. Our results suggest that the experimentally observed formation of the imine can be explained by the presence of hidden acid catalysts present in the reaction medium.

Resumo em Inglês:

Composite films are an alternative in the replacement of synthetic polymers. These films can be prepared from polysaccharides and used to store various drugs to be applied in different areas. In addition, aminoethoxyvinylglycine (AVG) is an ethylene inhibitor that prolongs shelf life of food. For this reason, this research aimed to take advantage of the brown algae Macrocystis pyrifera and Lessonia trabeculata to extract sodium alginate and produce films composed of sodium alginate/kappa-carrageenan/iota-carrageenan, which were plasticized with glycerol and polyethylene glycol 400 and loaded with aminoethoxyvinylglycine. The extracted sodium alginate was characterized by 1H and 13C nuclear magnetic resonance (NMR), size exclusion chromatography coupled with multi-angle light scattering (SEC-MALS), thermogravimetry (TG/DTG), Fourier transform infrared (FTIR), and X-ray diffraction (XRD); and the composite films were characterized by FTIR, XRD, TG/DTG, and scanning electron microscopy (SEM). Then, the drug release kinetics were investigated using Higuchi and Korsmeyer-Peppas kinetic models. The extracted alginates obtained were of low molecular weight, and the films showed desirable properties for AVG release. Furthermore, drug release profiles revealed that AVG release is governed by Fick’s Law, and this is favored at low temperatures. In summary, sodium alginate allows the preparation of composite films, which can replace synthetic polymers to be used in the loading and releasing of drugs.

Resumo em Inglês:

Vegetable proteases have been studied as milk coagulants, and artichoke flower (Cynara cardunculus L. var scolymus) has potential coagulant action as a substitute for microbial chymosin. The objective was to perform chemical characterization of aspartic proteases from artichoke flower (Cynara cardunculus L. var scolymus) by mid-infrared spectroscopy (MIR) and analytical measurements. Artichoke flower extracts were obtained and crude thistle flower extract and microbial chymosin were used as a reference. Plant extracts and microbial chymosin were analyzed for protein concentration, proteolytic activity (PA), milk clotting activity (MCA), specificity ratio (SR), effects of pH, temperature, NaCl and CaCl2 concentration on MCA and PA and characterized by electrophoretic, spectroscopic, chromatographic and storage stability. The results indicated that the crude extract of artichoke flower showed high MCA (510.08 SU mL 1), low PA (10.50 µg mg-1), SR (48.57) and storage stability for up to 90 days under frozen. The electrophoretic profile of artichoke flower resulted in a protein band with an apparent molecular weight of 32 kDa, associated with cardosin A. Artichoke flower may be a new alternative for commercial plant proteases with active enzymes for milk coagulation.

Resumo em Inglês:

Annual world production of sisal is estimated to be 400,000 tons, but the processing of sisal fiber generates around 160,000 tons of waste per year. The sisal bagasse is discarded, even though it is about 60% carbohydrates in its structure. Therefore, this work seeks to add value to sisal bagasse through the production of cellulose acetate membranes aimed at removing inhibitors from the fermentation process. The membrane was developed using a cellulose acetate polymer synthesized from cellulose isolated from sisal bagasse. Alkaline and acid pre-treatments resulted in 90% pure cellulose. The obtained cellulose acetate was confirmed by infrared spectroscopy. In the synthesis of the membranes, the influence of agitation time and temperature of the bath on the selectivity and porosity were evaluated in four tests, the third condition stood out with porosity of 26.23% and selectivity of 94.51% in the removal of the furfural and 36.62% of the acetic acid.