Resumo em Inglês:

United Nations Children's Fund (UNICEF)/United Nations Development Programme (UNDP)/World Bank/World Health Organization (WHO) implemented the Training in Tropical Diseases (TDR) program with excellent results; however, due to current challenges, this active program requires new and innovative solutions. Nowadays, Aedes aegyptis-borne diseases can be added among neglected diseases. Surveillance and control must be considered owing to a great risk of infection with dengue, chikungunya and zika viruses. Although investigations on several vaccines are in progress, new insights in term of development of drugs that evade from resistance are of paramount importance. Nanobiotechnology appears as one of the most innovative strategy in the search of new uses for old pharmaceuticals or in the development of innovative and intelligent nanomedicines for neglected diseases. Liposomes, solid lipid nanoparticles, nanoemulsions, polymeric nanoparticles, metallic nanoparticles, quantum dots, carbon dots and carbon nanotubes were the focus of the current advances. In this direction, we have focused this overview on new advances in diagnostic assays as nanobiosensors, antivirus and nanoinsecticides on Aedes aegyptis control.

Resumo em Inglês:

[18F]Fluoromisonidazole ([18F]FMISO) is a hypoxia imaging marker utilized in positron emission tomography. Novel FMISO precursors were prepared from a commercially available material, and several reaction factors that affect synthesis of [18F]FMISO were examined to achieve a higher fluorination yield. [18F]FMISO was obtained from radiosynthesis, followed by the hydrolysis of protecting groups with HCl. New 2-nitroimidazole precursor showed a higher [18F]fluorination and a higher synthetic yield. This result provided alternative guidelines for the preparation of hypoxia imaging marker.

Resumo em Inglês:

Synthesis, characterization and antioxidant activity of a new series of chiral N-boc oraganotellurium compounds, (CH3)3OC(O)NHCH(R)C(O)NHCH2CH2Te-C6H4-4-OCH3, containing carbamate and peptide groups have been reported in this paper. These chiral peptides were synthesized in good to excellent yields, via acid-amine coupling reaction of N-boc L-amino acids with 2-(4-methoxyphenyltelluro) ethylamine in presence of dicyclohexyl carbodimide (DCC) at room temperature. The elemental analyses, Fourier transform infrared (FTIR), 1H and 13C {1H} nuclear magnetic resonance (NMR) spectra and mass spectra were characteristic. Specific optical rotation (SOR) was also determined. In vitro antioxidant activity of these multi-functional compounds in methanol has been evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals with 2,6-di-tert-butyl-4-methylphenol (BHT) as a standard reference compound. The IC50 (inhibitory concentration 50) values of these chiral peptides revealed significant inhibition against DPPH radicals and found to be effective antioxidants.

Resumo em Inglês:

The development and validation of an analytical method for the determination of 51 pesticides in tomato using UPLC-MS/MS (ultra performance liquid chromatography coupled to tandem mass spectrometry) was performed in order to fulfill the requirements of the NBR ISO/IEC 17025:2005. The goal of the validation was to evaluate all required parameters, such as linearity of analytical curves, instrument and method limits of detection and quantification, matrix effect and accuracy (trueness and precision). Stock solutions of the pesticides were prepared in organic solvent by two different analysts independently, in order to validate this preparation by comparing the detector response areas of injections (n = 7). Pesticides were extracted from tomatoes applying the Dutch mini-Luke method with 30 mL of each solvent as acetone, petroleum ether as well as dichloromethane. A small aliquot of the organic solvent extract was evaporated and reconstituted in methanol with 0.1% of acetic acid (v/v) for UPLC-MS/MS analysis. The recovery experiments were done by spiking blank samples at 10, 20 and 50 µg kg-1, performed by two analysts, seven replicates for each concentration level plus the blank sample. From the 51 studied compounds, 46 showed recoveries within the acceptable range of 70-120% for all evaluated concentrations. For 82% of pesticides, the validated method limit of quantification was the lowest concentration studied (10 µg kg-1) . The intermediate precision was below 20% for all evaluated pesticides showing excellent repeatability of the method.

Resumo em Inglês:

This paper proposes an active search method aimed at finding objects with optimal or near-optimal y-property values, on the basis of x-variables obtained by indirect, less costly methods. The proposed method progresses in a sequential manner, starting from a small subset of objects with known y-values. At each iteration, the K-nearest neighbour regression technique is employed to obtain estimates ŷ for the objects with unknown y-values. The object with best ŷ value is then subjected to a direct analysis procedure for evaluation of the y-property. Examples are presented with simulated data, as well as actual quantitative structure-activity relationship (QSAR) and near-infrared (NIR) spectrometry datasets. The QSAR and NIR case studies involve the search for maximal antidepressant activity in a set of arylpiperazine compounds and maximal pulp yield in a set of eucalyptus wood samples, respectively. In all these cases, the active search yielded results closer to the maximal y-value compared to the classical Kennard-Stone algorithm for object selection.

Resumo em Inglês:

Response surface methodology was used to optimize the total phenolic content (TPC) result in white rice, using a new methodology that employed Fast Blue BB (FBBB) reagent, which reacts more specifically with phenolic compounds, along with direct QUENCHER procedure. This is the first time in which such conciliation between FBBB reagent and QUENCHER was done. The obtained model allowed to evaluate how the factors influenced the method linearity (R2), improving the choice of the optimal system condition. Furthermore, the similarity between experimental results and values generated by the model indicated the method validity within the studied region. Thus, the optimal condition determined in the present work was 30 min reaction time, 0.17 mL FBBB reagent and use of 5% NaOH as the catalyst for the reaction. This optimized condition suggested that the combination of the method, which used FBBB reagent and the direct QUENCHER procedure, was rapid and effective, yielding high TPC values (1488.73 mg of gallic acid equivalent per 100 g).

Resumo em Inglês:

The contribution of irradiation and the dihydroxybenzenes (DHB), catechol (CAT) and hydroquinone (HQ), added or formed as phenol oxidation intermediates, was evaluated for the reduction of FeIII and for phenol degradation via Fenton processes. The formation of CAT and HQ was observed during phenol degradation starting with Fe2+ or Fe3+ in the presence or absence of irradiation and their presence increased the rate of phenol degradation, more remarkably when initially added. Initial phenol degradation rate in the presence of DHB in the dark was much higher in comparison to their absence due to the initial higher and faster formation of Fe2+. However, degradation slows down due to the rapid oxidation of DHB, while under irradiation of free iron or citrate complex much higher mineralization is achieved in shorter time.

Resumo em Inglês:

The 1,3-dipolar cycloaddition reaction is a powerful tool for the cycloaddition of nitrile oxides to olefins, and this reaction is of considerable interest to obtain isoxazolines. Density functional theory (DFT) was used to study the 1,3-dipolar cycloaddition reaction mechanism that initially occurs between benzonitrile oxide and vinylacetic acid to yield a bicyclo, from successive cycloadditions. PBE1PBE, B3LYP and CAM-B3LYP functionals were used together with 6-311+G(2d,p) basis set. CCSD(T)/6-311+G(2d,p) calculations were done to compare the DFT energy barriers. The solvent effects were included using polarizable continuum model (PCM), with three different solvents. In the first cycloaddition, only the 3,5-regioisomer is expected. In the gas phase, the β face attack, that originates the trans-bicyclo, is slightly favored, but the cis-bicyclo is considerably more stable. However, the α face attack was favored with solvent effects. The PBE1PBE functional gives the closest activation energies and reaction energies to CCSD(T). The inclusion of solvent effects changes the preferential rotamer in each cycloaddition.

Resumo em Inglês:

Sixteen 1,4-diaryl-1,2,3-triazole compounds derived from the natural products veraguensin, grandisin and machilin G were synthesized, with yields of 78-92%. Biological activity tests against Leishmania amazonensis promastigotes showed that three of these compounds were the most active, with maximum inhibitory concentration (IC50) values of 1.1, 3.71 and 7.23 µM. One compound was highly active against Leishmania infantum, with an IC50 value of 5.2 µM, and one derivative showed an IC50 value of 28.6 µM against Trypanosoma cruzi trypomastigotes. Regarding structure-activity relationship (SAR), hybrid 1,2,3-triazolic compounds containing a methylenedioxy group, showed the best antileishmanial and antitrypanosomal activities.

Resumo em Inglês:

Formic acid extractions of Brazil nut and babassu coconut samples were undertaken prior to determination of Al, As, Ba, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, Sr, V and Zn in their meat and oil portions by inductively coupled plasma mass spectrometry (ICP-MS) in an effort to accomplish a first order fractionation of the trace elements between these two components. An optimized full factorial design was applied to establish the best conditions for extraction. Microwave-assisted nitric acid digestions of samples and fractions along with analysis of certified reference material TORT-2 established the efficiency of recovery of the trace elements as well as provided a verification of accuracy. The multiple responses were analyzed using a desirability function wherein the recovery of the trace elements by extraction was compared with the determination of the total content as determined by nitric acid digestion. Although most trace elements presented a recovery higher than 85% using a formic acid extraction, Al suffered consistently low results for all samples (40-50%). Except for Al and Cr, the majority of the trace elements were present in the defatted fraction of both samples, i.e., Al (50 and 10%), Cr (86 and 60%), Ni (30 and 10%) and Sr (8 and 20%) in Brazil nut and babassu coconut oil fractions, respectively.

Resumo em Inglês:

Infections caused by Staphylococcus aureus are ubiquitous and life threatening. Evolution of resistant strains has necessitated the need to continuously discover new drugs to combat such organisms. Diphenyl ethers, such as triclosan, have recently shown potential as antibacterial agents. In this study, a series of diphenyl amines were synthesized and evaluated for in vitro antibacterial activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Pseudomonas putida) bacteria. Preliminary results showed that six of the twelve synthesized molecules were active against Staphylococcus aureus. Most notable amongst them were compounds 2(2,4-dinitrophenylamino)phenol and 2(2-dinitrophenylamino)phenol having minimum inhibitory concentration (MIC) in the range of 7.8-15.6 µg mL-1 and 7.8-62.5 µg mL-1respectively for all the eight selected organisms. Five active compounds from the preliminary results were further screened against resistant S. aureus cultures where compounds 2(2,4-dinitrophenylamino)phenol, 2(2-dinitrophenylamino)phenol and 2-chloro-N-(2-(2,4-dichlorophenylamino)phenyl)acetamide gave encouraging results having MIC in the range 3.9-7.8 µg mL-1for most of the organisms. Results obtained above for the selected organisms and the resistant S. aureus strains conclude that hydroxyl group at 2-position of ring B potentiates the antibacterial activity and overcomes the antibiotic resistance.

Resumo em Inglês:

Derivatives of steviol, isosteviol and betulinic acid were prepared and tested in vitro against Plasmodium falciparum W2 (chloroquine-resistant) and Trypanosoma cruzi. The best results against P. falciparum were found for the betulinic acid derivatives 3-[(2,4-dinitrophenyl)hydrazono]lup-20(29)-en-28-oic acid and 3-hydroxy-20-[(2,4-dinitrophenyl)hydrazono]-29-norlupan-28-oic acid (values concentration in that the growth of the parasites is 50% inhibited, IC50 = 9.96, 6.45 and 21.06 µg mL-1, respectively). Isosteviol was inactive but its 4-nitro- and 2,4-dinitrophenylhydrazone showed moderate activity (IC50 = 17.50-22.58 µg mL-1). The derivatives of betulinic acid were more selective to the parasite when compared with hepatoblastoma HepG2 A16 cells. The results showed that nitrophenylhydrazone derivatives of lupane and beyerane terpenes are promising prototypes of antimalarial agents. Among the compounds tested against T. cruzi the oxime of isosteviol was active against both epimastigote and trypomastigote forms of the parasite.

Resumo em Inglês:

Ultraviolet characteristic profiles and infrared spectroscopic (FTIR) fingerprints of green bean extracts of Coffea arabica L., cv. IAPAR 59, cultivated in two planting patterns, rectangular and square, and at two different densities, 10,000 and 6,000 plants ha-1, identified as R10, R6, S10, and S6 were analyzed with principal component and hierarchical cluster analyses. A simplex centroid design for four solvents (ethanol, acetone, dichloromethane, hexane) was used for sample extraction. The largest chlorogenic acid (CGA) contents were found at the lower planting density. The dichloromethane extracts of the S10 treatment showed the highest levels of unsaponifiable lipids (cafestol and kahweol). The R6 treatment showed a slightly higher content of cafestol and kahweol. Cluster analysis of FTIR fingerprints confirmed that the CGA and caffeine levels differentiate the spatial arrangements. The FTIR fingerprints suggest that green beans from S6 and R10 were richer in lipids and the other two treatments had more sugars and proteins.

Resumo em Inglês:

The simultaneous voltammetric determination of antihypertensive drugs amlodipine besylate (AML) and atenolol (ATN) using a cathodically pretreated boron-doped diamond electrode (CP-BDDE) is reported for the first time. The anodic peak potentials of AML and ATN at a CP-BDDE were found to be 0.727 and 1.32 V (vs. Ag/AgCl (3.0 mol L-1 KCl)) in phosphate buffer (pH 7.0), respectively, by cyclic voltammetry. It was observed that the CP-BDDE possesses improved performance for the simultaneous determination of AML and ATN when compared to other carbon-based electrodes in these conditions. Using square-wave voltammetric technique, the obtained analytical curves were linear in the concentration range from 2.9-33 µmol L-1 for AML and 9.8-190 µmol L-1 for ATN, with limits of detection of 0.17 and 0.22 µmol L-1, respectively. The proposed method was successfully applied to the simultaneous determination of AML and ATN in pharmaceutical samples.

Resumo em Inglês:

A method for determination of arsenic in mineral fertilizers by continuous flow hydride generation atomic absorption spectrometry (CF-HG-AAS) was developed by using diluted acid and digester block with perfluoroalkoxy (PFA) tubes to sample preparation. An additional sample preparation procedure using microwave-assisted digestion was evaluated and compared with the proposed procedure. A full factorial design was applied to investigate the effect of the variables and the best conditions found were 7 mol L−1 HNO3 + 30% (m/m) H2O2 as reagents, 4 h of digestion and concentration of reagents diluted 1:1. The effect of concomitants on the analytical signal of arsenic was investigated and no one significant interference was observed, with recoveries ranged from 97 to 103%. The accuracy of proposed method was evaluated by certified reference material (NIST SRM 695) and recovery of 95% was obtained. The arsenic concentration (8.9 ± 0.2 mg kg−1) found in the fertilizer is below of maximum concentration established by Brazilian legislation.

Resumo em Inglês:

The purpose of this study is to prepare a new ion imprinted polymer for MoVI with high selectivity. Ion-imprinted polymer (IIP) particles were synthesized by thermally copolymerization. For the synthesis of the ion imprinted polymer, the ion pair of (MoVI-thiocyanate) and NR4+ was used. The ion pair was precipitated in an aqueous phase and then dissolved in acetonitrile as a porogen. The imprinted ion was removed using 10% (v/v) methanol in HCl (0.5 mol L-1). The unleached and leached IIP particles were characterized by infrared spectroscopy, thermogravimetric analysis, surface area analysis, scanning electron microscopy and energy dispersive X-ray analysis. The use of the new MoVI-IIP in solid phase extraction revealed a maximum adsorption capacity of 3.77 mg MoVIper gram of MoVI-IIP in optimum conditions of extraction. The selectivity coefficients of the IIP for Mo in comparison with other metal ions were also evaluated. The proposed Mo-IIP was successfully applied for MoVI determination in different types of water samples.

Resumo em Inglês:

Currently there is a crescent interest regarding the use of vegetable by-products for food fortification, in order to improve its nutritional quality. Cassava leaves are suitable as nutritional additives, however their cyanide content must be reduced to below 10 mg kg-1 of dry product. Thus, it was developed a method in drying laboratory oven which is able to reduce 99.85% of cyanide present in manioc leaves (from 35 mg kg-1 to 0.05 mg kg-1) while being 509% faster than the traditional method, and without substantial loss of omega-3 fatty acids and β-carotene.

Resumo em Inglês:

This work presents a study of the sorption of a pre-synthesized polysiloxane, poly(methyltetradecylsiloxane) - PMTDS, onto zirconized and titanized-silica particles that results in efficient stationary phases for reversed phase liquid chromatography. The sorbed materials, after 6 days at room temperature without any chemical or physical agent, denominated as self-immobilized stationary phase, present appropriate polymeric layer thicknesses that cover the metalized silica surfaces. The self-immobilization of polymer onto titanized silica particles produces more homogeneous polymeric coatings and stationary phases without silanophilic activity. Zirconized silica-based phases were more chemically resistant, despite their strong retention of basic solutes. In general, the chromatographic performance and chemical stability of metalized silica-based self-immobilized PMTDS phases were similar to conventional chemically bonded stationary phases.

Resumo em Inglês:

An energy dispersive X-ray fluorescence (EDXRF) analysis has been performed on Brazilian postage stamps to understand the elementary profile present in the paper, colored and postmarked areas, of stamps printed between 1850 and 1922. The EDXRF technique offered a fast, simple and nondestructive chemical analysis providing a profile of each postage stamp that provide a valuable data, such as information about raw materials employed in manufacturing process. Furthermore, we extend the methodology to detect counterfeit samples, since that some rare samples can cost fortunes, which naturally leads to cases of forgery in philately.

Resumo em Inglês:

Kaolinite-methanol-sodium stearate intercalation compound (Ka-MeOH-SS) was prepared by intercalation of kaolinite with dimethyl sulfoxide (DMSO) followed by displacing of DMSO with methanol and methanol by sodium stearate. The sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (thermogravimetry (TGA) and differential scanning calorimetry (DSC)) and transmission electron microscopy (TEM). The results show that the basal spacing of Ka-MeOH-SS was enlarged to 45.5-47.9 Å and parts of its layers cocked and curled. Stearate ions were grafted on the methoxy groups and arrayed aslant in the interlayer space of kaolinite with an inclination angle of 47.45º to 52.17º. Sodium ions were adsorbed around the SiO4 tetrahedron and interlayer carboxylate anions, whereas some of them entered into the ditrigonal hole of tetrahedral sheets. The thermal de-intercalation of Ka-MeOH-SS includes three steps and the activation energy E is 98.3 kJ mol−1, logarithm of pre-exponential factor lg(A / s-1 is 9.71 and the mechanism function is f(α) = −ln (1 − α) and G(α) = 1 − α.