Resumo em Inglês:

Over the years, laser-induced breakdown spectroscopy (LIBS) has been reported in the literature as an alternative to traditional methods of analysis, becoming well established among spectroanalytical techniques. LIBS is a technique widely used for qualitative approaches; however, it is necessary considerable effort for use in quantitative analysis, mainly due to severe matrix effects. These limitations make it difficult to broaden the application of LIBS in quantitative analysis. In this sense, this review discusses recent advances in calibration strategies applied in LIBS for minimizing matrix effects and enabling determination with satisfactory accuracy and precision. Applications, advantages, and limitations of the calibration strategies, such as matrix-matching calibration (MMC), internal standardization (IS), standard addition (SA), multi-energy calibration (MEC), one-point gravimetric standard addition (OP GSA), one-point and multi-line calibration (OP MLC), slope ratio calibration (SRC), two-point calibration transfer (TP CT), single-sample calibration (SSC), multiple linear regression (MLR), principal component regression (PCR), partial least squares (PLS) and artificial neural networks (ANN) are discussed.

Resumo em Inglês:

According to the World Health Organization, amoxicillin (AMX) is the most widely consumed antibiotic in the world. Consequently, there is great interest in the development of new technologies that allow the removal of this type of contaminant, as exposure to antibiotic residues can cause a variety of adverse effects, such as toxicity and antimicrobial resistance. In this work, AMX adsorption from aqueous solution was investigated using nickel ferrite nanoparticles. The nanoadsorbents were prepared by the coprecipitation method, annealed at 300 to 700 °C, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy (ME) and vibratory sample magnetometry (VSM). Nanoparticle size, pH and temperature were found to significantly affect the amount of adsorbed AMX. The pseudo-second order kinetic model described the adsorption process and the adsorption isotherm fitted to the Freundlich model. AMX adsorption capacity was 104-45 mg g−1 (miligram of AMX per gram of ferrite) for ferrite annealed at 300-700 °C, respectively. The nanoadsorbents employed showed higher AMX removal efficiency when compared to other iron oxides. Moreover, the good reuse results obtained showed their great potential for antibiotic removal by adsorption.

Resumo em Inglês:

An enantioselective six-step synthesis of (1S,2R)-ephenamine starting from readily available chiral amino acid is disclosed presenting 26% overall yield and high optical purity. The use of chiral phenylglycine as starting material was also studied and did not present satisfactory results due to a very sensitive a-carbonyl/benzylic stereogenic center that, in our hands, led to racemization.

Resumo em Inglês:

Wavelength dispersion X-ray fluorescence spectrometry (WDXRF) is a non-destructive technique and therefore attractive for gunshot residues (GSR) analysis. It is well known for determination of inorganic constituents of samples. However, X-ray scattering region spectral data is not commonly used, although it may provide information about organic constituents and their interactions. This work employed X-ray scattering region and inorganic elements spectral data for a better characterization of GSR. Swabs containing residues collected from the hand of people who fired (shooters group) and also from the hands of people which did not fire (control group) with guns were analyzed directly by the WDXRF. Brake pad and people who perform activities that favor the accumulation of characteristic elements of GSR on their hands were chosen to compose the control group. Principal components analysis (PCA) discriminated the GSR according to the firearm/cartridge used. However, similar GSR clustering did not occur without X-ray scatter data, showing the importance of X-ray scattering spectrum for GSR evaluation. The k-nearest neighbors (k-NN) method correctly classified all samples from shooters and control groups, employing from 1 to 5 nearest neighbors. No anomalous behavior was detected by PCA and hierarchical cluster analysis (HCA).

Resumo em Inglês:

This work proposes a spectrofluorometric method for the determination of total antioxidant capacity (CAO) in beverage samples, based on inhibition of thiochrome formation (λex = 370 nm, λem = 440 nm); a product of thiamine (vitamin B1) oxidation from K3Fe(CN)6. In the development of the method, gallic acid (GA) was used as a reference, and inhibition of thiochrome formation (in percentage) was used as the analytical response. The selectivity of the method was evaluated using seven different compounds (gallic acid, ascorbic acid, quercetin, butylhydroxytoluene (BHT), 6-hydroxy-2,5,7,8-tetramethylchroman-2 (Trolox), cysteine, and glucose). As proof of concept, the proposed method was applied in the determination of CAO in different samples, such as teas and infusions, red wines, and white wines. The results were compared with the Folin-Ciocalteu (FC), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS•+), and 2,2-diphenyl-1-picrylhydrazyl (DPPH•) methods using the linear correlation between the methods (at 95% confidence). We observed excellent agreement between the proposed method and FC (correlation coefficient (r) = 0.9768) and ABTS•+ (r = 0.9842), compared with DPPH• method (r = 0.8502). For the determination of total CAO in beverages, the proposed method developed proved to be fast, sensitive, simple, and the results were in agreement with established assays.

Resumo em Inglês:

This study developed a methodology for extracting and speciating CrIII and CrVI in sewage sludge by high performance liquid chromatography, inductively coupled plasma tandem mass spectrometry (HPLC-ICP-MS/MS). The optimal procedure was solid-liquid extraction in a water bath with stirring at 50 °C for 16 h and 50 mmol L−1 ethylenediaminetetraacetic acid (EDTA) extraction phase at pH 9.5. In the validated method, the recovery in the fortification experiment was greater than 70% and the relative standard deviation was less than 7%. Speciation analyses showed that all CrVI was spontaneously reduced to CrIII in the sludge sample. The limits of detection and quantification were 0.060 and 0.20 µg L−1, respectively, and the analyses of CrIII by means of ICP-MS/MS were linear from 0.20 to 50 µg L−1. The extraction efficiency of Cr specie in this validated method improved from 4.09 to 53.3% compared to the EPA 1311 method. The methodology was successfully applied to quantify CrIII in a sludge sample with a lower concentration than that established by European legislation 80568/4225/91.

Resumo em Inglês:

Carpotroche brasiliensis is a tree native to Brazil, belonging to the family Flacurtiaceae, whose seeds contain a group of cyclopentenyl fatty acids: gorlic (12%), chaulmugric (27%), and hydnocarpic (48.7%). These compounds are considered the main therapeutic agents in the treatment of leprosy. In the present study, a series of novel triazole compounds were obtained by conjugation between hydnocarpic acid and functionalized azides via copper(I)-catalyzed azide-alkyne cycloaddition reaction (CuAAC). Hydnocarpic acid and its derivatives were tested against estrogen-positive breast carcinoma (MCF-7), hepatocellular carcinoma (HepG2), and non-small cell lung cancer (A549) cell lines. The (R)-(1-(pyridin-2-ylmethyl)-1H-1,2,3-triazol-4-yl)methyl-11-(cyclopent-2-en-1-yl)undecanoate (8) displayed promising antiproliferative activity against A549 cells. We demonstrated that this compound selectively inhibited the viability of A549 cell cultures. Furthermore, compound 8 inhibited the clonogenic capacity of A549 cells, and this effect was associated to its ability to inhibit cell cycle progression at G1 phase. These findings indicate that 8 is a promising antitumor agent on A549 cells and support further studies to evaluate the molecular mechanisms underlying its antiproliferative activity. In addition, hydnocarpic acid should be considered as a promising chemical prototype to obtain novel antineoplastic agents.

Resumo em Inglês:

Considering the increasing number of low cost vegetable oil product adulterations, it is necessary to assess the authenticity of the lipid sources used in the dog food manufacture, consequently different brands and classifications of feed were analyzed to verify the product authenticity by gas chromatography (GC) with flame ionization detector (FID) and by electrospray ionization mass spectrometry (ESI-MS). Fatty acid (FA) composition analysis was performed to compare the FAs amount in samples with the respective guarantee levels stated by the manufacturers on its product label. Gas chromatography with flame ionization detector (GC-FID) results for omega-3 and 6 percentages are within the limits presented by each manufacturer, while the timnodonic + cervonic acids amount information presented on feed sample labels is not in accordance with GC-FID results. Consequently, the samples were analyzed by ESI-MS, the results exposed the chicken oil presence in the feed and eicosapentaenoic (EPA) + docosahexaenoic (DHA) acids absence, since no lipid profiles similar to fish oils or triacylglycerols (TAGs) containing these two FAs were found. Thus, the information presented on labels are in disagreement with the results obtained both by GC-FID FA composition analysis and by ESI-MS lipid profile analysis. Principal component analysis (PCA) confirmed that the main contribution was from FAs found by GC-FID.

Resumo em Inglês:

This work focuses on the validation and application of solid phase extraction followed by high-performance liquid chromatography (SPE-HPLC) analysis of important endocrine disruptors compounds (EDC) from different classes in highly complex wastewater matrix. The endocrine disruptors investigated included three different categories: pharmaceuticals (sulfamethoxazole (SMZ), trimethoprim (TMP) and diclofenac (DCF)), hormones (estrone (E1), 17α-ethinylestradiol (EE2) and 17β-estradiol (E2)) and plastic materials (bisphenol A (BPA)). The method involves pre-concentration by SPE using Strata-X extraction cartridges followed by HPLC coupled with diode array detector (DAD). As the assumption of homoscedasticity was met for analytical data, ordinary linear regression procedure was applied to the data. The method was considered validated for 7 EDC after consistent evaluation of the key analytical parameters. Recoveries were ranged from 52.3 to 179.6%. Limits of quantification were in the range 6.0-0.4 µg L−1. The described method was applied to evaluate the occurrence and removal efficiency of EDC in two biological sewage treatment plants (STPs). The influent mean concentrations of E1, E2 and EE2 hormones were 79.54; 175.09 and 102.19 µg L−1, respectively, while for SMZ, TMP, DCF and BPA were 215.17; 187.01; 218.97 and 87.12 µg L−1 for STP A, respectively. The efficiencies for the removal of EDCs ranged from 0 to 79.4%.

Resumo em Inglês:

Endogenous and environmental factors can influence the lipid contents of fishes among which, in the Amazon River, seasonal dynamics influences stand out. Herein, nine most consumed Amazonian fish species had their lipid composition evaluated in terms of effects of tissue, season and eating habits. Higher amounts of lipids were obtained from fish livers than dorsal muscles. Statistical analysis has shown that Amazonian fishes presented different lipid profiles according to their eating habits, which mainly comprised saturated fatty acids to distinguish detritivorous livers, and linolenic acid, cholesterol, polar lipids for carnivorous and piscivorous fish muscles. Furthermore, in Amazonian fish, some very important lipids for human nutrition were found, such as w-3 and w-6 fatty acids whose availability depended on the tissue metabolism and fishes’ eating habit along with the seasonal periods. For example, our findings indicated that the piscivorous fish C. monoculus presented higher levels of linoleic acid for livers than linolenic acid and the opposite occurred for muscles. The w-6 and w-3 fatty acids ratio was influenced by the season dynamic of the Amazon River and availability of food according to each specific eating habit, pointing mainly to the piscivorous fishes as the healthiest fish for human consumption.

Resumo em Inglês:

Malaria, a parasitic infection caused by Plasmodium falciparum, is a serious global public health problem. The enzyme enoyl-acyl carrier protein (ACP) reductase present in a limiting step in the biosynthesis of fatty acids type II was used to search for novel molecules with potential inhibitor by virtual screening techniques. A flavonoid library obtained in ChEMBL database (n = 4,008) was filtered through physico-chemical similarity using the Euclidean distance as a criterion. The selected molecules were subjected to molecular docking using the scoring function GridScore in the DOCK 6.5 software. The top 30 ranked molecules by molecular docking were submitted to the AuPosSOM 2.1 software with the aim of clustering molecules by means of intermolecular interactions in order to understand the patterns of these interactions with enoyl-ACP reductase from Plasmodium falciparum (PfENR). We observed the importance of flavonoid moiety to hydrophobic interactions with the active site of enzyme, this confirmed the choice to study this metabolite class as PfENR inhibitors. Moreover, it was possible to recognize which intermolecular interactions contribute to the molecular recognition process.

Resumo em Inglês:

A new analytical protocol has been developed for the determination of mercury in surface sediments using dithiothreitol (DTT) as a new chelating reagent for the extraction. This protocol requires a small sample mass (250 mg), 4.0 mL of a 0.1 M (pH = 9.0) aqueous DTT solution, and sonication for 30 min, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). The limits of detection and quantification determined were 6 and 18 ng g−1, respectively. The method was validated using three standard reference materials, SRM NIST 1646a, PACS-2, and MESS-3, with recoveries in the range of 102-124%. The new analytical protocol was successfully applied in riverine surface sediments, revealing concentrations in the range of 220-340 ng g−1. The results obtained by CV-AFS were compared to those obtained by DMA-80 (direct mercury analyzer). The linear regression equation obtained was [CV-AFS] = (0.91 ± 0.07)[DMA-80] + (0.04 ± 0.02), revealing no systematic difference between the analytical methods. Hence, the proposed method does not require the complete digestion of the sediment, and was found to be comprehensive, simple, accurate and suitable to be employed for determination of mercury in sediment samples.

Resumo em Inglês:

Pharmaceutical cocrystals are composed of a drug and a coformer and are currently gaining attention due to their possibility of improving drug solubility. Quantitative determination of cocrystals is usually carried out by liquid chromatography method, but an alternative for the same is derivative UV spectrophotometry. Cocrystals of lamotrigine (LAM) were formed with nicotinamide (NIC) in order to improve the solubility of LAM. The aim of this study was to develop and validate a simple, low-cost, environment friendly, first-order derivative spectrophotometric method for simultaneous determination of LAM and NIC in cocrystals. Determination of LAM and NIC was performed at 244.4 and 271.6 nm, respectively. The method was accurate with recovery values of 98.21-101.52%, and precise (relative standard deviation (RSD) < 1.88%). Robustness evaluated by Plackett-Burman design showed no significant influence of the factors (pH, scanning speed, and sonication time) on LAM and NIC assays. The developed method was compared with a high performance liquid chromatography (HPLC) method and applied to study the cocrystal stoichiometry and solubility. The results indicated a molar ratio of 1:1 and that the cocrystal is more soluble than the drug. This study demonstrated that the first-order derivative method is feasible for drug and coformer determination in cocrystals and is a suitable alternative to chromatographic methods.

Resumo em Inglês:

Natural and synthetic sulfur-bearing organic compounds have many applications in medicinal chemistry. This article reports the preparation of amphiphilic β-hydroxy sulfides, sulfoxides, and sulfones derived from cardanol and glycerol. Thiolysis of cardanol epoxide 3 with various thiols (4a-4j) in ethanol or water yielded the corresponding β-hydroxy sulfides 5a-5j (61-95%). Treatment with 30% H2O2 in acetic acid at ambient temperature completely converted these products into β-hydroxy sulfoxides 6a-6j and sulfones 7a, 7c-7f, 7h-7j. The synthesized compounds were characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, high-resolution mass spectroscopy (HRMS) and performed the in vitro evaluation antimicrobial activities against standard strains of Staphylococcus aureus and Escherichia coli. Compounds 5a, 5d-5f, and 5h-5j proved moderately active against S. aureus. None of the compounds were active against E. coli. β-Hydroxy-sulfides 5a-5j were also evaluated for antioxidant properties but failed to exhibit significant activity.

Resumo em Inglês:

One of the methods used by the oil industry to increase production is to inject water, containing polymer, into the reservoir. The viscosity of the aqueous solution is primarily responsible for the efficiency of this method, and is achieved using polymers with high molar mass. However, polymer degradation can occur during pumping and fluid displacement in the porous medium, reducing the efficiency of the polymer flooding method. Therefore, it is important to monitor the molar mass of the polymer in the produced water. Size-exclusion chromatography (SEC) is a powerful method for determining average molar mass of polymers, but the impurities present in the produced water, such as salts and residual oil, can significantly affect the analysis. There is no method described in the literature for pretreating produced water before injecting it into the chromatograph. Therefore, the purpose of this work was to develop a reliable method for this pretreatment, without affecting the molar mass of the polymer. The results showed that an efficient method, which does not cause polymer degradation, must contain four steps: (i) heating, (ii) regular filtration, (iii) elution in poly(divinylbenzene) resin, and (iv) dialysis.

Resumo em Inglês:

A series of fifteen new piperine-derived diesters was synthesized through the substitution reaction between the salt of piperic acid, obtained through piperine basic hydrolysis, with the δ-chloro-esters, obtained through the cleavage of tetrahydrofuran (THF) with acyl chlorides in the presence of ZnCl2. The final compounds were obtained with yields ranging from 50 to 84% and were characterized by infrared (IR) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR). The new compounds were evaluated in silico in regard to their ADME (absorption, distribution, metabolism, and excretion) properties, and in vitro for their antimicrobial activity against bacteria strains (Staphylococcus aureus and Pseudomonas aeruginosas), yeast fungi (Candida albicans and C. tropicalis) and filamentous fungi (Aspergillus fumigatus, A. flavus and A. niger). The results from the in silico studies of Lipinski’s rule of five showed that most compounds present good pharmacological possibilities, and the results from in vitro antimicrobial activity showed that 8 of the 15 synthesized compounds displayed antimicrobial activity, inhibiting the growth of 40-80% of tested strains, with a minimum inhibitory concentration (MIC) interval ranging from 1024 to 256 µg mL−1.

Resumo em Inglês:

Rosemary (Rosmarinus officinalis L.) is known for its bioactive compounds with high antioxidant potential and pharmacological properties, such as antibacterial, antidepressant and anti-inflammatory. These properties are attributed to the presence of (poly)phenolic compounds. In the literature there is no extraction of these compounds with a totally non-toxic solvent, capable of applying the extract directly to the food. This work aimed to optimize the extraction conditions of bioactive compounds from the rosemary leaves using water as solvent. According to the analysis of variance parameters, a cubic model of high order of significance was obtained with adjusted R2 (R squared) > 0.947. The optimal conditions of the antioxidant potential for conventional and ultrasonic agitation were: temperature 70 °C, 30 min of extraction and the solvent/solute ratio of 25, resulting in an antioxidant potential of 6861 and 7126 µmol L−1 Trolox, respectively. The electrospray ionization mass spectrometry (ESI(−)-MS/MS) analysis showed the presence of antioxidant compounds such as: carnosol (m/z 329.20), rosmanol (m/z 345.03) and rosmarinic (m/z359.14) acids. The response surface methodology evaluated the influence of the main parameters of the bioactive compounds extraction from rosemary using only water as solvent, in addition to the use of less time and sample mass, resulting in lower cost.

Resumo em Inglês:

Azure A (AZA) and azure B (AZB) phenothiazine dyes are used for clinical and medical purposes, and their functions can be altered via interactions with proteins. However, no kinetics information on the interactions between phenothiazine dyes and bovine serum albumin (BSA) is available. Surface plasmon resonance was used to determine the energetic and dynamic of the BSA-AZA and BSA-AZB complexes formation at pH 7.4. At temperature ≤ 16 °C, the formation of activated (DH‡a,12°C,AZA= -310.57 kJ mol-1 and DH‡a,12 °C,AZB= -256.37 kJ mol-1) and thermodynamically stable (DH°12°C,AZA= -314.56 kJ mol-1 and DH°12°C,AZB= -265.73 kJ mol-1) complexes was driven by enthalpy, while at temperature ≥ 20 °C, by entropy, (TDS‡a,28°C,AZA= 207.49 and TDS‡a,28°C,AZB= 190.69; TDS°28°C,AZA= 277.50 and TDS°28°C,AZB= 257.26 kJ mol-1). Hydrophobic interactions were fundamental to the complex stability and the increase in number of -CH3 groups in the dyes do not affect kinetic and thermodynamic parameters. Our results could help optimize the medical and pharmaceutical applications of phenothiazine dyes.

Resumo em Inglês:

A novel dual-signal amplificatory electrochemiluminescence (ECL) deoxyribonucleic acid (DNA) biosensor was designed for the determination of Hg2+. One amplification unit was gold nanoparticles (AuNPs) modified on a glassy carbon electrode, and the other was single-stranded DNA (ssDNA) (with amino at the 3’ terminal and thiol at the 5’ terminal) labeled with a carboxyl-functionalized Ru@SiO2 nanoparticles (Ru1@SiO2) as a nanoprobe. The ECL biosensor was obtained through a strong gold-sulfur bond between Au on AuNPs modified electrode and thiol in the nanoprobe. In the presence of Hg2+, the ECL signal reduced because the T-Hg2+-T existed between the ECL nanoprobe and the complementary DNA (c-DNA), which exhibited a sensing platform for the detection of Hg2+. The results revealed that the reduced ECL intensity was linearly proportional to the logarithm of the Hg2+ concentration in the range of 1.0 pmol L-1-100 nmol L-1 with limit of detection 0.02 pmol L-1. The proposed method was applied for the analysis of Hg2+ in the river water and the results were in good agreement with that obtained by atomic fluorescence spectroscopy.

Resumo em Inglês:

The ofloxacin (OFLOX) is a second-generation synthetic antibiotic that can be classified as a multifunctional drug, but is a poorly soluble drug, which influences its efficiency. The inclusion complexes of OFLOX with β-cyclodextrin (βCD) or hydroxypropyl-β-cyclodextrin (HPβCD) can improve the chemical characteristics of the drug; however, studies showing the biological activity of these inclusion complexes are still scarce. The present work aimed to investigate the multifunctionality of the OFLOX and their inclusion complexes. Thus, the 1:1 βCD/OFLOX or HPβCD/OFLOX were prepared and analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis (TGA and DTA), 1H nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC). The antitumor and antibacterial effects were assessed. The results confirm the formation of the inclusion complexes, which had lower minimum inhibitory concentration (MIC) values, higher cytotoxicity and promoted the apoptosis. The present study showed, for the first time, the promising effects of the inclusion complexes as antitumor, improving the biological activities of the uncomplexed ofloxacin.

Resumo em Inglês:

So far, there is neither a vaccine nor a specific antiviral drug to prevent or treat COVID-19 (coronavirus disease) infection. Recent studies have been done to investigate the capacity of human immunodeficiency virus type 1 (HIV-1) protease inhibitors be used in the treatment of COVID-19 patients. Some of those drugs have shown to be promising. Natural chemical substances from plants provide a good source of chemicals for the development of potential novel antiviral drugs against viral pathogens including HIV-1. In January 2020, a new promising target useful for structure-based drug design was elucidated and stored in the Protein Data Bank. In this context, the objective of this study was to determine whether and how a set of both non-natural and natural HIV-1 protease inhibitors could dock to that novel crystallized severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) main protease and, consequently, to identify potential lead compounds to treat COVID-19 infected patients. The results showed that two non-natural compounds, danoprevir and lopinavir, and one compound from plant, corilagin, produced strong interactions with the inhibitor binding site of SARS-CoV-2 main protease. It is expected that this work contributes to validate the use of HIV-1 protease inhibitors against SARS-CoV-2.

Resumo em Inglês:

This work describes the isolation of pure bergenin from Peltophorum dubium roots with good yields and its further derivatization through Williamson synthesis. The alkyl derivatives of the bergenin were identified by nuclear magnetic resonance and mass spectrometry data analysis. Among them, three derivatives were reported for the first time herein, 8,10-dihexyl-bergenin, 8,10-didecyl-bergenin, and 8,10-ditetradecyl-bergenin, along with three previously reported ones (8,10-dimethylbergenin, 8-methylbergenin, 8,10-dioctyl-bergenin). Most derivatives of the bergenin displayed moderate cytotoxicity against Artemia salina, except the 8,10-dihexyl-bergenin (lethal concentration doses for 50% (LC50) = 70.55 µg mL-1). The antimicrobial assay showed that all derivatives selectively inhibited the Gram-positive bacteria Staphylococcus aureus, and two of them (8,10-dihexyl-bergenin and 8,10-didecyl-bergenin) had promising activities (minimum inhibitory concentration (MIC) = 5.1-6.2 µmol L-1). In addition, bergenin displayed interesting inhibition on acetylcholinesterase (half maximal inhibitory concentration (IC50) = 141.19 ± 0.41 µmol L-1), while its semi-synthetic derivatives displayed modest activity. Our results revealed that the antibacterial activity of bergenin could be greatly improved through its structural modification.