Resumo em Inglês:

Quinones and organochalcogens are classes of compounds with great biological applicability, such as antioxidant, anticancer, anti-Alzheimer, and antidepressant activities, among others. Thus, the combination of these two classes of compounds is important to obtain new hits with biological activities that are additive or synergistic. Several methodologies for the preparation of this class of hybrid compound have been widely described. Many of the prepared hybrid molecules have shown increased biological activities and, in some cases, to act as two distinct pharmacophores. In this review, methods for the preparation of selenium-quinones, tellurium-quinones and their biological applications are highlighted.

Resumo em Inglês:

The accumulation of antibiotics by plants is a currently concern associated to yield reduction and transference of antibiotic residues along the food web. Maize is a staple food in many parts of the world; it is also considered an important ingredient in animal nutrition. Considering the lack of validated analytical methods for the analysis of ciprofloxacin (CIPRO) and enrofloxacin (ENRO) in the shoot of Zea mays maize, we developed a reliable reversed-phase high-performance liquid chromatography method with fluorescence detection (HPLC-FLD). This method was validated for linearity, matrix effects, precision, accuracy, limits of quantification (LOQ) and detection (LOD), and robustness. The analytical curves were linear with coefficient of determination (R2) of 0.9907 for CIPRO and 0.9962 for ENRO. The LOD values were 16.65 and 6.57 μg kg−1 for CIPRO and ENRO, respectively, whereas LOQ values were 50.44 μg kg−1 (CIPRO) and 19.92 μg kg−1 (ENRO). HPLC-FLD also displayed good precision and accuracy. Therefore, the proposed method can be considered a reliable and useful tool for the analysis of ciprofloxacin and enrofloxacin in the shoot of maize.

Resumo em Inglês:

The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 °C. X-ray diffraction, UV-Vis, X-ray absorption and 57Fe Mössbauer spectroscopies were used to identify iron sites. The obtained results showed that ZnII replaces the relatively smaller FeIII cation in the tetrahedral sites, increasing the cubic lattice dimension, and this replacement remarkably enhances the catalytic effectiveness of the Zn-spinel ferrite towards the indigo carmine degradation compared to undoped magnetite. The indigo carmine degradation experiments were carried out using photo-Fenton method in which 50 mL of indigo carmine dye aqueous solutions (20 mg L−1, pH 3.0), 20 mg ZnxFe(3-x)O4, and 2.0 mL H2O2 (aqueous solution at 0.028 mol L−1) were placed under UV light at 25 °C. Under these experimental conditions the degradation rate of indigo carmine was superior to 98%.

Resumo em Inglês:

Urban air pollution is still an emerging environmental problem, it causes damage to health and is difficult to be controlled in urban centers. The population of large metropolises is often exposed to concentrations of nitrogen oxides (NOx), mainly due to vehicle emissions. Epidemiological studies claim that exposure to these oxides is strongly correlated with the incidence of different types of cancer. This work evaluated the impact of NOx emissions on the air quality of five Brazilian urban centers, using passive sampling. The NO/NO2 ratio indicated photochemical aging in the atmosphere of all the cities studied. Although there has been a predominant trend towards decreasing of nitrogen oxides concentrations in many locations, average annual values > 40 μg m−3 NO2 have been found, in Brazil as well as other parts of the world, what indicates the need to control air pollution in these areas.

Resumo em Inglês:

Valsartan is an antihypertensive active pharmaceutical ingredient (API), it is used in the amorphous state in the commercial products. As amorphous materials are metastable, amorphous valsartan can crystallize to valsartan E, promoting changes in the dissolution and bioavailability of the drug. Tablets containing metastable forms of APIs need special conditions for transport and storage in order to avoid crystallization (from amorphous state) or polymorphic transitions (from less stable crystalline structures). A multivariate calibration model based on interval partial least squares (iPLS) regression allied to net analyte signal (NAS) algorithm was built to simultaneously quantify amorphous (VAL-AM) and crystalline (VAL-E) valsartan. Mixtures of VAL-AM and VAL-E were used to produce tablets in order to simulate the crystallization of VAL-AM in a range from 0 to 100% of conversion. The calibration set included 11 samples and 5 samples were used as the external validation set. The following parameters of merit (POM) were obtained for both polymorphs in order to evaluate the calibration model quality: root mean square error (RMSE) for cross validation (RMSECV), validation (RMSEV) and calibration (RMSEC), sensitivity (SEN), selectivity (SEL), analytical sensitivity (γ), inverse analytical sensitivity (γ−1), limit of detection (LOD) and limit of quantification (LOQ).

Resumo em Inglês:

The Ipojuca River is considered the third most polluted river in Brazil due to the intense anthropogenic activities in the surrounding urban areas. The most important effluent is sewage discharge, which is responsible for considerable contamination. Traditional analyses (infrared spectroscopy, organic matter (OM), elemental analysis and granulometry) and advanced analysis of sterols by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were applied to evaluate the levels of urban contamination from sewage in 10 surface sediment samples from the Ipojuca River, in a stretch located in the Caruaru city, Pernambuco, Brazil. The results pointed to sandy sediments, rich in OM from anthropogenic sources (predominant). Eight different sterols were detected with a total concentration in a range between < limit of quantification (LOQ) and 1,634.4 µg g−1. Coprostanol (fecal biomarker) was detected in high concentrations (557.3 µg g−1) in the sediment collected close to an open-air market (considered the largest in the world), making it the most contaminated in the region. Multivariate statistical analysis revealed areas tending towards contamination and that 90% of sediments were contaminated by sewage. These results can be considered useful for preventive and remedial actions toward promoting human health in this region.

Resumo em Inglês:

This work describes the synthesis and application of an europium(III) complex, [Eu(TTA)3(2-pyr) (H2O)], containing 2-thenoyltrifuoroacetonate (TTA) and 2-pyrrolidone (2-pyr) as ligands, obtained as white solid and soluble in ethanol. In solution, the complex showed red emission, characteristic of the EuIII emission in the solid state (λexc = 375 nm and λem = 612 nm). The complex was tested with PbII, CdII, and HgII ions in water. The effect of metal ions was monitored and evaluated by hypersensitive transition 5D0 → 7F2 (612 nm). The results show that PbII suppresses the complex luminescence and present high sensitivity, according to the values for the Stern-Volmer constant (K SV = 2300 L mol−1), showing good linearity, i.e., determination coefficient (R 2) of 0.9913, and low limit of detection (LOD = 6.03 µM). Luminescence quenching increased with the increasing concentration of PbII. These results indicate that the synthesized complex is a potential luminescent sensor for detecting PbII in a simple and fast way, being applicable for routine environmental analysis. When applied as an ethanol sensor in gasoline, the complex hypersensitive transition intensity decreased with the increasing volume of ethanol in gasoline, reaching the values of R 2 = 0.9815 and LOD = 4.94% v/v.

Resumo em Inglês:

Considering the economic potential of secondary metabolites, researches have been focusing several strategies in order to explore and enhance the accumulation of these metabolites in plant matrices in a broad context. One of those strategies is the development of suitable methodologies for the determination of some elicitors, such as salicylic acid (SA). Since literature presents only a few analytical methods for the quantification of SA in plants, this study developed, validated and evaluated these metabolite contents in Polygala species using capillary zone electrophoresis with ultraviolet-visible detection. The background electrolyte (BGE) consisted of 15 mmol L−1 of hydroxymethyl-aminomethane and 30 mmol L−1 of 2-hydroxy-isobutyric acid, pH = 3.9. The BGE was chosen using a rational procedure to increase selectivity and reduce migration time. The method presented rapid performance, migration time less than 0.76 min for salicylic and phthalic acid (internal standard), precision results for peak area were better than 2.9% (intra-day) and 2.8% (inter-day) and the responses for the analytes were linear (range of 1-5 mg L−1), with limits of detection and quantification of 0.2 and 0.6 mg L−1, respectively. The developed method was applied for 39 samples of plant extracts.

Resumo em Inglês:

The essential oils from Aniba parviflora and the balsam from Protium rubrum, which are two woody scented Amazonian species, were analyzed by gas chromatography-mass spectrometry (GC-MS), 1H and 13C nuclear magnetic resonance (NMR). GC-MS analysis revealed the presence of unknown constituents. These compounds were then isolated, analyzed and characterized by NMR. Both substances presented distinct woody notes that contributed to the bulk woody character of the crude oils.

Resumo em Inglês:

Plutella xylostella cause considerable harm to the production of broccoli, Chinese cabbage, cabbage and cauliflower. The control of P. xylostella is mainly performed using commercial insecticides, which have even led to the emergence of resistant populations. Two easily available natural products found in different plants essential oil, thymol and eugenol, stand up as possible novel agents to control this pest. In this work a series of alkylated and acylated derivatives of eugenol and thymol were synthesized and screened for antifeedant, larvicidal and ovicidal activities against P. xylostella. The results of biological activities assays suggest that the novel 1,1’-[1,8-octanediylbis(oxy)]-bis(4-allyl-2-methoxy-benzene) (5) was the most toxic in the larvicidal test. Compounds 1-butoxy-2-isopropyl-5-methyl-benzene (8) and hexanedioic acid 1,6-bis(2-isopropyl-5-methyl-phenyl)-ester (10) were the most toxic in the ovicidal assay. The compound 8 presented the most antifeedant activity. Most of the compounds obtained were more active than commercially available insecticidal deltamethrin and azadirachtin.