Resumo em Inglês:

A molecularly imprinted polymer (MIP) was prepared using the anti-inflammatory diclofenac (DCF) as a template. A non-imprinted polymer (NIP) was also prepared as a control. These MIP and NIP were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET), revealing a higher porosity in the first. Then both were used in the modification of graphite-polyurethane composites electrodes (GPUE). Differential pulse anodic stripping voltammetry was used for DCF determination at GPUE MIP DCF containing 2.5% (m/m) of the modifier in perchloric acid, pH = 2.0, after previously optimized conditions such as 300 s of accumulation time, +0.2 V accumulation potential (vs. SCE (saturated calomel electrode)), 50 mV pulse amplitude and 10 mV s-1 scan rate. A linear dynamic range from 0.010 to 0.20 μmol L-1 and a limit of detection (LOD) of 0.99 nmol L-1 were found, using GPUE 2.5 MIP DCF. DCF was determined in commercial pharmaceutical formulations and in synthetic urine samples, with recoveries between 101 and 102% (n = 3) and 101% (n = 3), respectively. The results agreed with the reference high-performance liquid chromatography (HPLC) within 95% confidence level, according to Student’s t-test. Interference from meclofenamic and mefenamic acids, which are structurally similar to DCF, was also evaluated. Interferences could not be totally avoided, but MIPs presented a considerable ability in discriminating the voltammetric response for DFC, despite the close structural similarity with the interferents.

Resumo em Inglês:

The fungal Hemileia vastatrix is the causal agent of coffee leaf rust, one of the worst and devastating disease in coffee cultures worldwide. As a result of our research on natural products for the development of novel agrochemicals, we found that the hexane extract from leaves of the Brazilian medicinal plant Garcinia gardneriana, at 500 μg mL-1, inhibited in 98% the germination of H. vastatrix urediniospores. This extract showed no phytotoxicity when tested for seed germination and seedling growth inhibitory activity using sensible plant species. Also, the hexane extract from leaves was tested for anti-acetylcholinesterase activity, which constitutes a mechanism of action of major commercial insecticides used in agriculture, and showed low activity even at concentrations about two times higher than the half maximal inhibitory concentration (IC50) found in the antifungal assays. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the hexane extract is constituted mainly by the pentacyclic triterpene lupeol, together with a series of sesquiterpenes as minor components. This is the first report on the investigation of antifungal, phytotoxic and acetylcholinesterase activities of extracts from leaves of G. gardneriana. These findings indicate that G. gardneriana may constitute a promising source of natural products for controlling the coffee leaf rust fungus.

Resumo em Inglês:

A series of novel betulin-28-hydrazone derivatives (7a-7o) were synthesized. All compounds were evaluated for their in vitro cytotoxicities in four human carcinoma cells (HepG2, MCF-7, HCT-116 and A549). Among them, compound 7l displayed the most potent cytotoxicity with an IC50 (concentration of the tested compound that inhibits 50% of cell growth) value of 7.37 ± 0.38 μM against MCF-7 cells. The preliminary cellular mechanism studies indicated that compound 7l could induce MCF-7 cells apoptosis. The above findings indicated that compound 7l may be used as a lead compound for antitumor agents with improved efficacy.

Resumo em Inglês:

Furanaphthoquinones are well known in medicinal chemistry for exhibiting relevant structural heterogeneity and bioactivities. In this work, it was synthesized a series of furanaphthoquinones through a tandem reaction between lawsone (8) and cyclic ketones in the presence of morpholine. This strategy provides an efficient and general method for synthesizing furanaphthoquinones with activity against the epimastigote form of Trypanosoma cruzi (T. cruzi), the parasite that causes Chagas disease. Compound 9b was the better prototype, and it exhibited high potency for causing parasite death, showed reduced acute toxicity towards mammalian cells, and was capable of rupturing the epimastigote plasma membrane and acting on sterol 14α-demethylase (CYP51). Additionally, 9b reduced trypomastigote viability by 99% after 24 h. Candidate 9b demonstrated the best and most promising profile when bound to CYP51.

Resumo em Inglês:

A novel recognition method was put forward to identify the producing areas of the flue-cured tobacco leaves rapidly and non-destructively by using a near-infrared (NIR) spectrometer and a multi-layer-extreme learning machine (ML-ELM) algorithm. In contrast to traditional linear discriminant analysis (LDA) and extreme learning machine (ELM) algorithms, the accuracy, sensitivity and specificity were the highest for the proposed ML-ELM algorithm. The ML-ELM models for different producing areas of Yunnan tobacco leaves had the best generalization ability and prediction results. Besides, the above three algorithms were also identified by using the chemical index data. The experimental results indicated that the NIR spectroscopy technology together with ML-ELM algorithm achieved the best prediction performance both using the NIR spectral data and chemical index data. It indicates that the combination of NIR and ML-ELM can recognize different producing areas of Yunnan tobacco leaves rapidly, accurately, and non-destructively.

Resumo em Inglês:

A gas chromatography method with a flame ionization detector enabled by relative response factor was developed to determine the individual and the total content of esters in biodiesel. This method accounts for different response factors of the detector for a homologous series of esters that may be present in biodiesel. In this way, the determination of the total ester content of a reference sample (100.5%) was done with more accuracy by the proposed procedure (100.2%) than by official analytical methods: EN (74.68%) and ABNT (118.2%). Another advantage of the developed method is the possibility of determining individual ester concentrations, which provides information on several important biodiesel properties such as oxidative stability and cold flow properties. The mean absolute error in the determination of the individual ester content was ca. 1.1%.

Resumo em Inglês:

The gasification reactivity of coal char is affected by numerous experimental variables, and char structure is one of the dominant factors. In this work, Raman spectroscopy, powder X-ray diffraction (XRD), and N2 adsorption were used to investigate the physical and chemical structure of char prepared under different pyrolysis conditions. Three kinds of pyrolysis reactors, fluidized-bed reactor (FL), entrained-flow-bed reactor (EF), and fixed-bed reactor (PT), were designed and used to prepare the char samples. Lignite was pyrolyzed in a fixed-bed reactor with a heating rate of 10 ºC min-1, and the final temperature was 1000 ºC. The gasification reactivity of char was characterized in a quartz fixed-bed reactor under CO2, H2O, and their mixtures at 750 ºC. FB reactor produces chars with a smaller interlayer spacing of aromatic layers (d002), and FL reactor produces chars with a larger mean crystallite size along the c-axis (Lc) and aromaticity (ƒa) but inhibits the growth of mean crystallite size along the a-axis (La). The content of small aromatic rings, which is higher in the FL reactor, positively affects the initial intrinsic reactivity.

Resumo em Inglês:

Eugenia is the largest neotropical genus in the Myrtaceae family. The genus has a wide geographical distribution, occurring from Mexico to Argentina. Eugenia species are rich in essential oils. Essential oils have applications in perfumery, cosmetics, food, pesticides and medicines. Several factors can influence the chemical composition and yield of essential oils, such as extraction technique, season of the year, genetic variations and environmental conditions. The understanding of how much each of these factors interferes in the formation of essential oils can contribute both to the development of more efficient production processes and to the ecological knowledge of the species of the genus. This study aimed to assess the influence of environmental variables on the chemical composition of essential oils from Eugenia species. The method used was to carry out chemometrics analyzes (regression analysis, factor analysis and multivariate analysis of variance) to explain the influence of environmental factors on the chemical composition of essential oils. The estimated regression model was significant (p-value < 0.05). Environmental variables analyzed significantly influenced and account for 11.5% of the variation observed in the chemical composition of essential oils. Phytochemical pattern of essential oil composition was also significantly different among Eugenia species.

Resumo em Inglês:

In this study, two analytical methods were evaluated to determine haloacetic acids (HAAs) in drinking water samples. Direct aqueous injection (DAI) and solid phase extraction (SPE) were evaluated and determination was performed by liquid chromatography tandem mass spectrometry (LC-MS/MS) with a hydrophilic interaction chromatography (HILIC) analytical column. Limits of quantification (LOQ) were between 10 and 500 µg L-1 by DAI and, considering a 125-fold pre concentration step, between 0.08 and 2.0 µg L-1 by SPE. Five HAAs exhibited good linear correlation coefficients, accuracy (70-120%) and precision (≤ 20%) using DAI, while accuracy (50 120%) and precision (≤ 20%) were reached for SPE, with the exception of monobromoacetic acid (MBAA), which showed accuracy < 50%. DAI showed to be a simple, fast and promising technique that reduces operators’ exposure and may replace methods that require a derivatization process, reaching LOQs below those established by the regulations for most analytes. SPE using polymeric cartridges and 2 mL of acetonitrile as elution solvent showed to be an interesting alternative for samples with low levels of HAAs. After evaluating the techniques, DAI was successfully employed to determine HAAs in drinking water samples and DCAA was detected in samples in concentrations between 15.3 and 33.6 µg L-1 and DBAA in concentration below 10 µg L-1.

Resumo em Inglês:

Benzimidazole and its derivatives are molecules that have diverse biological properties, therefore we synthesized and studied a new benzimidazole to understand their physical/chemical properties. The compound was obtained through a new synthetic route, using graphite oxide, in the absence of solvent, with crystalline packaging supported by C-H…N and C-H…π interactions. According to the frontier molecular orbitals, the compound is kinetically stable while the molecular electrostatic potential map confirms the site of molecular interactions involving nitrogen atoms and the π-system. This comprehensive study on synthesis, structural description and theoretical calculations can support ongoing studies in pharmaceutical science.