A New Isoflavone and Other Constituents from Roots of Clitoria guianensis
A new isoflavone named pratensein-7-O- β -D-rutinoside [(-)-7-O- α -L-rhamnopyranosyl-(1 → 6)- β -D-glucopyranosyl-5,3 ’ -dihydroxy-4 ’ -methoxyisoflavone] and the known compounds biochanin A-7-O- β -D-rutinoside, 6-deoxyclitoriacetal 11-O- β -D-glucopyranoside, 6-deoxyclitoriacetal, (2S)-naringenin-6-C- β -D-glucopyranoside, (2R)-naringenin-6-C- β -D-glucopyranoside, tachioside, and koaburaside were isolated from the roots of Clitoria guianensis (Aubl.) Benth var. guianensis (Fabaceae), a subshrub found in the Brazilian Cerrado biome. The structures of the compounds wer...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

A New Energetic Complex: Synthesis, Structure, and Combustion Catalysis Performance
The potential of tetrazole-based ligands for forming energetic complexes applied in pyrotechnics and propellants is demonstrated with the use of 5,5 ’ -(1,3-phenylene)bis(1H-tetrazole) (H2BTB) to generate an energetic complex with high energy. A new energetic complex of PbII-tetrazolate, [Pb2(BTB)2(H2O)8] ·5H2O (1), was synthesized and structurally characterized by single crystal X-ray diffraction. Structural analysis reveals that the central PbII ions present two distinct coordination environments in the asymmetric unit, including distorted pentagonal bipyramid and distorted tetragonal pyramid geom etries, re...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Imiquimod/β-Cyclodextrin Inclusion Complex: Experimental and Theoretical Studies
Imiquimod (IMQ), an immune response modifier, is used for topical treatment of basal cell carcinoma and actinic keratosis. The very poor aqueous solubility of imiquimod gives rise to difficulties in designing aqueous formulations with this drug. One approach that is widely used to enhance drug solubility is complexation with cyclodextrins. The formation of the inclusion complex between IMQ and β -cyclodextrin was investigated in solution and in solid state. IMQ aqueous solubility was improved in the presence of citric acid. The experimental results and molecular modeling indicated the formation of the inclusion comple...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Expeditious Syntheses to Pharmochemicals 1,3-Dihydroxyacetone, 1,3-Dichloro-, 1,3-Dibromo- and 1,3-Diiodoacetone from Glycerol 1,3-Dichlorohydrin Using Homogenous and Heterogenous Medium
New efficient and reproductive routes to production of 1,3-dihydroxyacetone (1), 1,3-dichloroacetone (6), 1,3-dibromoacetone (7) and 1,3-diiodoacetone (8) from glycerol 1,3-dichlorohydrin (3) were developed. The synthesis of 1 was processed in three steps from glycerol 2 (1,3-selective chlorination of 2 to 3, oxidation of 3 to 6 and subsequent di-hydroxylation) in 51% overall yield. On the other hand, 7 and 8 were produced from3, via a trans-bromination and trans-iodination, respectively, followed by oxidation and hydroxylation steps, in 38-52% overall yield. It was used homogeneous media with different reagents (HCl/AcOH,...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

New Magnetic Fe Oxide-Carbon Based Acid Catalyst Prepared from Bio-Oil for Esterification Reactions
In this work, bio-oil (an organic matrix rich in oxygen functionalities) was used to efficiently dissolve and disperse Fe3+ which upon thermal treatment produced a carbon containing dispersed and encapsulated Fe oxide magnetic nanoparticles. These materials were prepared by dissolution of 8, 16 and 24 wt.% Fe3+ salt in bio-oil followed by treatment at 400, 450, 500 or 600 ºC in N2 atmosphere. X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopies (TEM), elemental analysis, thermogravimetric-mass spectrometry (TG-MS), potentiometric titration, Raman and Mössbauer spectroscopies showed that ...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

New Insights into the Partitioning of Phenothiazine Dyes in Aqueous Two-Phase Systems
Aqueous two-phase systems (ATPSs) have proven to be efficient and environmentally safe methods for extracting chemical species. However, the driving forces behind the partition of solutes in these systems are still little understood. A complete thermodynamic partitioning of phenothiazine dyes was investigated in poly(ethylene oxide) (PEO) + salt + water ATPSs. Standard transfer parameters (Gibbs free energy change ( Δ trG º), enthalpy change ( Δ trH º) and entropy change (T Δ trS º)) were evaluated, and their dependence on the dye structure, electrolyte nature and tie line length (TLL). All...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

1H NMR and Chemometric Methods to Estimate the Octane Number in Brazilian C Gasolines
Brazilian gasoline type C can be purchased with octane number as the main difference. This quality parameter directly affects the price. Intermediate formulations may not be easily distinguished from conform samples due to similarity in visual appearance and physicochemical properties. The use of anhydrous ethanol as an additive also influences the octane values of the product. In this context, the present study describes the use of 1H nuclear magnetic resonance spectroscopy (1H NMR) associated with chemometrics in the characterization and distinction of gasolines by different octane number. Conform samples of common, prem...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Copaifera multijuga, Copaifera pubiflora and Copaifera trapezifolia Oleoresins: Chemical Characterization and in vitro Cytotoxic Potential against Tumoral Cell Lines
Copaifera species (Fabaceae) comprises approximately 70 species of large trees, from which 16 can be found in Brazil. The oleoresins obtained from their trunk are widely used in Brazilian folk medicine, which display important antitumoral potential. Chemically, these oleoresins are mainly composed of a mixture of sesquiterpenes and diterpenes. In this paper we are describing the isolation and identification of 12 already known terpenes from oleoresins obtained from three different Copaifera species (C. multijuga, C. pubiflora and C. trapezifolia) and 2 novel diterpenes (ent-16-hidroxy-3,13 clerodadien-15,18-dioic acid and ...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

New Diesters Derived from Piperine: in silico Study and Evaluation of Their Antimicrobial Potential
Piperine, previously extracted from black pepper (Piper nigrum L.), was used as a precursor for the synthesis of twelve new diester derivatives. The final products were obtained through the bimolecular nucleophilic substitution reaction (SN2) of the alkyl 2-chloroacetates and the salt of piperic acid, obtained from the basic hydrolysis of piperine. The compounds were synthesized with yields of 55-84% and characterized by infrared spectroscopy and 1H and 13C nuclear magnetic resonance. The evaluation of the compounds ’ potential as new drug candidates was done through an in silico study of ADME properties (absorption,...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Evaluation of the Oxidation Degradation Process of Biodiesel via 1H NMR Spectroscopy
Biodiesel is a suitable alternative to replace the petro-diesel. The biodiesel is formed by unsaturated esters easily degraded by interferences of oxygen, temperature, contact with metals or contaminants. The aim of this research was to investigate the biodiesel degradation process via 1H nuclear magnetic resonance (NMR) spectroscopy, observing the olefinic, bis-allylic and allylic protons signals of the chemical bonds, and by the induction period of the Rancimat. Biodiesel samples with metallic ions (Fe and Cu) and with rosemary natural extract were analyzed. The metal compounds showed a catalytic effect in the samples an...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Biodegradation of the Pyrethroid Pesticide Esfenvalerate by a Bacterial Consortium Isolated from Brazilian Savannah
New biocatalysts for bioremediation techniques are necessary nowadays. Therefore, a bacterial consortium isolated from Brazilian Savannah was employed for biodegradation of 100 mg L-1 esfenvalerate in liquid culture medium. The bacterial consortium (Lysinibacillus xylanilyticus CBMAI2085, Bacillus cereus CBMAI2067, Lysinibacillus sp. CBMAI2051 and Bacillus sp. CBMAI2052) biodegraded this pyrethroid efficiently. The assays were conducted in triplicate, and after 12 days, 90% of the pesticide was degraded producing 3-phenoxybenzoic acid (35.0 ± 3.1 mg L-1) and 2-(4-chlorophenyl)-3-methylbutanoic acid (34.0 ± 2....
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Synthesis of ZnO Nanoparticles by the Sol-Gel Protein Route: A Viable and Efficient Method for Photocatalytic Degradation of Methylene Blue and Ibuprofen
The photocatalytic degradation of methylene blue dye and ibuprofen drug was studied in the presence of zinc oxide, synthetized by the protein sol-gel route. The catalyst, calcined at 1000 ºC, presented a tendentious morphology to filaments characteristic of ZnO crystalline, characterized by X-ray diffraction (XRD) and confirmed by the presence of Zn energy band in X-ray photoelectron spectrometer (XPS). The result of ultraviolet (UV) light photodegradation of this work is comparable to others that made use of more complex routes, considering the degradation of 97% of methylene blue dye solution and the solution of the...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

A Simple Fluorescent Chemosensor for Detection of Zinc Ions in Some Real Samples and Intracellular Imaging in Living Cells
A new designed fluorescent chemosensor TYMN ((E)-1-((thiazol-2-ylimino)methyl)naphthalen-2-ol) for highly sensitive and selective tracing of trace amount of Zn2+ ions in some real samples was synthesized and characterized. The sensor TYMN can detect Zn2+ ions via fluorescence enhancement with a high selectivity over a wide range of metal ions, especially Cd2+. The sensor showed large fluorescence enhancement upon complexation with Zn2+ and simultaneous color change from yellow to orange. The limit of detection was analyzed to be 0.0311 μ M with a linear dynamic range 0.1-1.0 μ M. The sensor could work in a pH span of...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Chemical and Spectroscopic Characteristics of Anthrosol (Amazonian Dark Earth) and Surrounding Soil from the Brazilian Amazon Forest: Evaluation of Mineral and Organic Matter Content by Depth
The chemical and spectroscopic characteristics of soil organic matter (SOM) isolated from Amazonian dark earth (ADE) and surrounding soil (SR) were evaluated according to the soil depth. The results showed opposite trends for the soils. While ADE featured SOM with a greater aromatic condensation degree and greater hydrophobicity in the top layer, the SR showed more aliphatic and polar SOM. The SOM arrangement from ADE was less hydrophobic, aromatic, and more polar in depth. In contrast, the SOM from SR showed an increase in molecular weight and hydrophobicity. Besides the aromatic protection in the SOM from ADE, there was ...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Chitosan Nanoparticles Loaded with Carvacrol and Carvacryl Acetate for Improved Anthelmintic Activity
Carvacrol (CV) and carvacryl acetate (CVA) are bioactive compounds that have anthelmintic action and the nanoencapsulation may be an alternative to potentialize their efficacy. The aim of this work was to nanoencapsulate CV and CVA using chitosan/gums and evaluate cytotoxicity and the anthelmintic activity. A 24 factorial experimental design was performed to determine the influence of gum type (arabic or chich á), amount of surfactant and the number of layers in the nanoencapsulation degree. CVA and CV presented encapsulation efficiency (EE) optimum values of 90 and 20% (experiments 8 and 9), respectively. The monol...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

New Synthetic Quinolines as Cathepsin K Inhibitors
This study presents the synthesis of nine 2,4-diphenylquinolines, including five phthalonitrile quinolines dyads, and the evaluation of their CatK inhibitory activity. Among the evaluated compounds, 4b was the most potent inhibitor with an IC50 (half-maximal inhibitory concentration) value of 1.55 µM (against Z-Phe-Arg-MCA substrate) acting in an uncompetitive inhibition mode. Molecular docking studies provided important information on the interaction of the inhibitor with the enzyme showing that these quinoline derivatives can play an important role as CatK inhibitors. (Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Catalytic Dehydration of Glycerol to Acrolein over Aluminum Phosphate Catalysts
Gas phase conversion of glycerol to acrolein over a variety of aluminum phosphate (AlP) catalysts synthesized by a simple replacement reaction method with a variation in calcination temperature (300-700 ºC, AlP-300, AlP-400, AlP-500, AlP-600, and AlP-700, respectively) has been investigated. The textural properties, acidities and coke contents of the samples were also determined. The catalysts were presented in an amorphous state when the AlP sample was calcined below 500 ºC. Further increasing t he calcination temperature promoted the formation of orthorhombic α -AlPO4 crystal. The weak acid sites increase...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Preparation and Characterization of the β-Cyclodextrin Inclusion Complex with Benzbromarone
Benzbromarone (BZB) is a drug that has diuretic activity and is used in the gout treatment. Its therapeutic efficiency is decreased by its low water solubility (11.8 mg L-1) and highly hydrophobic aspect (logP 2.7), which are responsible for affecting its intestinal absorption and bioavailability. BZB inclusion complex (IC) aims at increasing the drug solubility in water and reduce adverse effects resulting in more efficient formulations. The coprecipitation encapsulating method was used to obtain the IC of BZB in β -cyclodextrin ( β -CD) and the complex (BZB@ β -CD) was characterized via physical-chemical a...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

A Simple and Effective Liquid-Liquid-Liquid Microextraction Method with Ultraviolet Spectrophotometric Detection for the Determination of Bisphenol A in Aqueous Matrices and Plastic Leachates
This study shows the development and application of an analytical method for the determination of bisphenol A (BPA) in aqueous samples such as tap, river and mineral water and plastic leachates, based on an extensive literature search to understand the gaps for the determination of BPA in aqueous samples. We found that most of the methods in the literature employ some chromatographic strategy, and, to a much lesser extent, non-chromatographic instrumentation. In this scenario, we show an ultraviolet spectrophotometric-based method that can be used for routine analysis. Sample preparation was conducted by means of solvent e...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Antimicrobial High-Density Polyethylene (HDPE)/ZnO Nanocomposites Obtained by in situ Polymerization
Nanostructured zinc oxide (ZnO) prepared by combustion in solution was used to obtain nanocomposites. The ZnO particles were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and scanning electron microscopy (SEM), showing crystallite size of 32 nm and a superficial area of 32.6 m2 g-1. Nanocomposites with 1, 3, and 5 wt.% of ZnO in the polymeric matrix were obtained using the in situ polymerization of ethylene with catalytic activities between 1500-1700 kg (molZr h PE)-1. The high-density polyethylene nanocomposites (PEZnO) were characterized by thermogravimetric analysis (TGA), differential scanning...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Chemoenzymatic Synthesis and Anti-Inflammatory Activity of Fatty Acid Amides Prepared from Bertholletia excelsa (Brazil Nut) Triglycerides
This study reports the synthesis of fatty acid amides (FAA), analogous to anandamide, prepared from Brazil nut oil (BNO), using Amano lipase from Pseudomonas fluorescens as a catalyst of direct aminolysis, with a good yield (95-68%). The anti-inflammatory effects of BNO and FAA were evaluated by the carrageenan-induced paw edema method. Analysis of the formation of edema showed that these FAA, at all dose used, significantly reduced the development of edema. (Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Tenofovir Disoproxil Fumarate: New Chemical Developments and Encouraging in vitro Biological Results for SARS-CoV-2
The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led society to live with a serious public health problem. In this sense, repositioning of antiretrovirals has captured the attention of the scientific community. Tenofovir disoproxil fumarate (TDF) is an antiretroviral compound that is used to treat acquired immune deficiency syndrome (AIDS) and hepatitis B. In this short report, we present a scale-up investigation of TDF by in situ infrared spectroscopy monitoring and a forced degradation study to describe a new degradation product. Finally, we have evaluated TDF in vitro for SARS-CoV...
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Dreaming is a Must, Despite the Current Crisis
(Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - July 27, 2020 Category: Chemistry Source Type: research

Synthesis, Characterization and Antimicrobial Activities of Pentacyclic Oxadiazadiborinanes
In this study we have expanded upon a family of substituted pentacyclic oxadiazadiborinane derivatives from the condensation of carbohydrazide with ortho-formylphenyl boronic acid derivatives containing a variety of chemical and physical properties. All new complexes have been characterized fully including two single crystal X-ray diffraction studies which confirm the solid-state structure of these species along with an unusual methanol activation product, which appears to be a minor solid-state side product. The lack of inherent solubility of these compounds in common physiological media precluded us from doing traditiona...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Pyrimidine Derivatives: QSAR Studies of Larvicidal Activity against Aedes aegypti
The present study investigated the activity of pyrimidine derivatives against Aedes aegypti. Two compounds, 3c and 3d showed excellent larvicide activity. Additionally, quantitative structure-activity relationship (QSAR) models were built using multiple-linear regression and partial least squares with descriptors generated from Dragon and VolSurf+ software, respectively. The best model is obtained with multiple linear regression (MLR), leading to a robust model. Moreover, the QSAR model is validated by means of some internal validation techniques in order to check its reliability, quality and robustness for predicting the ...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Combined Analytical Py-GC/MS, SEM, FTIR and 13C NMR for Investigating the Removal of Trace Metals from Aqueous Solutions by Biochar
In this study, the efficiency of biochar (BC) produced from sugarcane bagasse at different pyrolysis temperatures (300, 400, 500 and 600 ºC) for simultaneous removal of CdII, PbII, CuII, CrIII, NiII and ZnII ions from aqueous solutions was assessed. All BC were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), 13C nuclear magnetic resonance (13C NMR) and pyrolysis-gas chromatography-mass spec trometry (Py-GC-MS). The effects of pyrolysis temperature, initial adsorbate concentration and adsorbent dosage on adorption capacity of BC were examined through batch experiments. The BC ...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

A Choline Chloride-Ethylene Glycol Deep Eutectic Solvent Based on Magnetic Polydopamine with Preconcentration and Determination for Sulfonylurea Herbicides in Water Samples
In this study, a novel deep eutectic solvent (DES) containing choline chloride and ethylene glycol was synthesized, and the magnetic polydopamine (PDA) was modified with this deep eutectic solvent to form Fe3O4@PDA-DES. Fourier transformed infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometer were used to characterize the proposed adsorbent. Then, this magnetic material was used as an adsorbent in the magnetic solid phase extraction process for the extraction of four sulfonylurea herbicides in water samples. The main parameters relevant to this method were investigated. Under the optimum co...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Evaluation and Geostatistical Study of Toxicological Risk by Water Ingestion with Al, Ba, Fe and Pb in Communities Close to Industrial Areas in the Brazilian Amazon
This study provides a risk assessment and risk maps related to the consumption of water contaminated by Al, Ba, Fe and Pb in an industrial area in the Brazilian Amazon. A total of 120 samples of drinking water were collected from 26 locations in the municipality of Barcarena, Par á State. Multiple elements were analyzed by inductively coupled plasma optical emission spectrometry. The quantifiable elements in the samples were Al, Ba, Fe and Pb. Risk assessment was performed according to U.S. Environmental Protection Agency (USEPA) procedures. Results indicate that the highes t potential risk of non-carcinogenic adver...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Voltammetric Determination of Free and Total Manganese in Tea Infusions
Tea infusions are a source of mineral nutrients, including manganese. Although it is classified as an essential element, the excess of manganese is toxic for humans and its toxicity depends on its bioavailability. In this context, we propose a simple procedure to determine free and total manganese in black tea infusions by square-wave voltammetry (SWV). Free manganese was directly quantified in the samples after simple sample dilution in 0.1 mol L − 1 acetic acid/acetate buffer (pH = 4.5) while total manganese determination was carried out after sample digestion with oxidant mixture (HNO3 + H2O2). For comparison, clo...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Chemical Prospection of Qualea grandiflora Mart. Fruit and Stem Extracts and Their in vitro and in vivo Antiplasmodial Activity
In this study, we investigated the antiplasmodial activity of Q. grandiflora fruit and stem extracts against Plasmodium falciparum. The polar extracts of both fruits and stems showed promising in vitro antiplasmodial activity against sensitive and resistant P. falciparum strains (half-maximal inhibitory concentration (IC50) = 1.2 and 4.2 ng mL-1, respectively), low cytotoxicity against human hepatic cells (IC50HepG2 ≥ 400 ng mL-1), and a noteworthy selectivity index (SI ≥ 322 and ≥ 96, respectively). The fruit ethanolic extract revealed significant oral efficacy at 100 mg kg-1 in a mouse model of P. berghei malari...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Simultaneous Quantification of Plasma Catecholamines and Metanephrines by LC-MS/MS
The quantification of the low levels of catecholamines and metanephrines in biological fluids is important for clinical screening of pheochromocytoma/paraganglioma and diagnosis of overtraining syndrome in athletes. We introduce a novel, accurate and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of these biogenic amines in human plasma. Simple protein precipitation combined with rapid 2-aminoethyl diphenylborinate-assisted liquid-liquid extraction allow us to quantify catecholamines and metanephrines over broad concentration ranges. Target analytes were monitored...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Two Years Monitoring of Ethyl Carbamate in Sugar Cane Spirit from Brazilian Distilleries
This paper describes the monitoring of ethyl carbamate concentration in sugar cane spirit from industrial distilleries in Brazil. In total, 18 distilleries from Minas Gerais and S ão Paulo states were evaluated, with, a total of 336 samples from August 2017 to August 2019. The ethyl carbamate was analyzed using a previously validated mass spectrometric method. Analytical curves presented coefficient of determination (R2) values higher than 0.99, and quality control samples s howed a relative standard deviation (RSD) below 9%. Concentrations of ethyl carbamate ranged from not detected to 1608 µg L-1, with mean ...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Fast Verification of Buffalo’s Milk Authenticity by Mid-Infrared Spectroscopy, Analytical Measurements and Multivariate Calibration
Mid-infrared spectroscopy (MID), chemical composition and physicochemical characteristics associated with chemometrics were used to rapidly detect and quantify the amount of cow ’ s milk added in buffalo ’ s milk. A total of 165 samples, divided into buffalo ’ s milk, buffalo ’ s milk added with cow ’ s milk (10 to 90%) and cow ’ s milk were evaluated to obtain fat, protein, lactose, total and defatted solids, urea, pH, acidity, cryoscopic index and band absorbances in the spectra associated with principal component analysis (PCA), multiple linear regression (MLR) and partial least squar...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Concentration of Metals in Plant Litter Produced in Regions of Caatinga in Southwest Bahia, Brazil
The objective of this study was to investigate the concentration of metals (Fe, Co, Ca, Cu, Ni, Mg, Mn and Zn) in Caatinga plant litter in the southwest region of Bahia. Plant litter was collected in summer (January/2017) and winter (August/2017). Concentrations were determined by flame atomic absorption spectrometry (FAAS). The results were submitted to multivariate analysis, principal component analysis (PCA), and hierarchical cluster analysis (HCA). The average amount of plant litter found in January and August was 1190 and 1329 kg ha-1, respectively. The twigs fraction provided the largest amount of biomass to the plan...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

A Comparative Study on the Groebke-Blackburn-Bienaymé Three-Component Reaction Catalyzed by Rare Earth Triflates under Microwave Heating
Over the last twenty years, the Groebke-Blackburn-Bienaym é (GBB) reaction has been emerged as a powerful tool to access different nitrogen-based heterocycles as privileged scaffolds in medicinal chemistry. This multicomponent reaction is usually catalyzed by ordinary Brønsted or Lewis acid catalysts. Herein, we present a comparative study on the catalyt ic efficiencies of different rare earth triflates in GBB reactions under microwave heating, involving 2-aminopyridine or 2-aminothiazole, as aminoazole component, and different aldehydes and aliphatic isocyanides. The use of gadolinium(III) triflate as cheape...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Mango (Mangifera indica) Aroma Discriminate Cultivars and Ripeness Stages
In this study, it was demonstrated that both the variety and ripening stage have a significant impact on the aroma of mango. The volatile compound profile of “ Tommy Atkins ” , “ palmer ” , “ espada ” and “ Carlota ” varieties in green and ripe stages were characterized by headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME/GC-MS). Thirty-three volatile compounds were identified, 30 from “ Tommy Atkins ” , 29 from “ espada ” , 25 from “ palmer ” and 10 from the “ Carlota ” variety. The major compo...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Application of a Chemometric Method to Interpret Spectrophotometric Data Obtained for Degradation of an Organic Dye in Water Using Manganese Oxide
Birnessite type manganese oxide ( δ -MnO2) was synthesized for use in degradation of the cationic dye methylene blue in aqueous solution. The material was characterized using infrared spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller (BET) surface area calculations. The removal of the dye from aqueous solutions was evaluated considering the effects of the following variables: pH, manganese oxide concentration, contact time, and temperature. UV-Vis spectroscopy analyses indicated achievement of 99 and 95% removal of methylene blue (7 mg L-1) at pH 2.0 and 4.0, respectively, after 120 min of contact with the ...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

High Conversion of Palm Olein to Ethyl Esters Using a Strong Anion Exchange Resin: Study of the Operational Parameters
Biodiesel, known as a mixture of fatty acid ethyl/methyl esters, is seen as an alternative, ecofriendly, biodegradable and renewable non-fossil fuel. The use of heterogeneous catalysts for biodiesel synthesis can solve several problems associated with the homogeneous alkaline catalyzed-transesterification. Therefore, this work reports the evaluation of the commercial resin Amberlyst A26OH, a strong anion exchange resin, as a heterogeneous catalyst for the batch transesterification of refined palm olein with ethanol. It was studied the effects of the main operational parameters, considering the molar ratio of the reaction m...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Hopfield Neural Network-Based Algorithm Applied to Differential Scanning Calorimetry Data for Kinetic Studies in Polymorphic Conversion
A general kinetic equation to simulate differential scanning calorimetry (DSC) data was employed along this work. Random noises are used to generate a thousand data, which are considered to evaluate the performance of Levenberg-Marquardt (LM) and a Hopfield neural network (HNN) based algorithm in the fitting process. The HNN-based algorithm showed better results for two different initial conditions: exact and approximated values. After this statistical analysis, DSC experimental data at three heating rates for losartan potassium, an antihypertensive drug, was adjusted by the HNN method using different initial conditions to...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Production of Furanic Compounds and Organic Acids from Brazilian Pequi (Caryocar brasiliensis Camb.) Residues Using Green Chemistry
In the current search for renewable energy sources, residual biomass has gained ground in the concept of biorefinery. Furanic compounds such as 5-hydroxymethylfurfural (HMF), furfural (FF) and derivatives such as levulinic acid (LA), obtained from biomass, have emerged as important industrial chemical platforms. In this sense, this work aimed to use pequi bark, typical biomass and abundant in the Brazilian cerrado, in the production of HMF, FF and LA using the ionic liquid 1-n-butyl-3-methyl-imidazole bromide ([BMIM][Br]). The analysis of chemical composition of pequi bark showed that it has potential for use in the produc...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Understanding Solvent/Bixin Interactions by Raman Spectroscopy
In this work, Raman spectroscopy and density functional theory (DFT) calculations have been used in order to understand the nature of the interaction between the carotenoid bixin and organic solvents with dielectric constant varying from ca. 2 (toluene) to ca. 47 (dimethyl sulfoxide). Raman shifts registered for the main carotenoid marker band, the C=C stretching mode (1525-1533 cm-1), were used as a probe to monitor spectral changes due to chemical interaction between bixin in the solid state with the analogous solvated species. Raman spectra of bixin in solution showed significant bathochromic shifts in the wavenumber po...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Furfural Hydrodeoxygenation over a Ruthenium-Based Bifunctional Catalyst in the Presence of a Direct Source of H2
This work presents the results obtained for the gas chromatography-mass spectrometry (GC-MS) monitoring of the liquid-phase hydrodeoxygenation (HDO) reaction of furfural (FFR) to 2-methylfuran (MF) over a bifunctional Ru/RuOx/C catalyst in the presence of a direct source of H2. Hydrogenation and hydrogenolysis reactions of FFR and of the intermediate furfuryl alcohol (FA), respectively, were independently studied to provide insights on the HDO mechanism. The mass spectra monitoring of the kinetic isotope effect indicated the HDO reaction occurs through a two-step mechanism comprising of an initial ruthenium-mediated hydrog...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

New Heteroleptic RuII/Diphosphine Complexes with Cytotoxicity against Human Breast and Murine Ascitic Sarcoma 180 Tumor Cells
The preparation, characterization, theoretical calculations and biological application of four RuII complexes with 2-picolinate (pic), 2,2 ’ -bipyridine (bipy) and P-P as ligands [P-P = 1,1-bis(diphenylphosphino)methane (dppm-1), 1,2-bis(diphenylphosphino)ethane (dppe-2), 1,3-bis(diphenylphosphino)propane (dppp-3) or 1,1 ’ -bis(diphenylphosphino)ferrocene (dppf-4)], is here presented. The complexes 1-4, with general formula [Ru(pic)(P-P)(bipy)]PF6, were characterized by elemental analysis and by infrared (IR), UV-Vis, nuclear magnetic resonance (NMR 1H and 13P{1H}) spectroscopies, cyclic voltammetry and X-ray c...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Nanostructured Lipid Carriers Loaded with 17-α-Estradiol Accumulate into Hair Follicles
To improve 17- α -estradiol targeting in alopecia treatment, a formulation of nanostructured lipid carrier (NLC) prepared by the sonication method was developed. The physicochemical characterization showed an average diameter of 96 ± 15 nm and the average zeta potential of -17 ± 6 mV. In addition, the encapsulation efficiency (EE) of 17- α -estradiol, assessed by ultra-performance liquid chromatography (UPLC) fluorescence, was 99.6 ± 0.3%. Physical stability of NLC stored at room temperature was followed for 42 days through several physicochemical parameters, such as diameter, zeta potentia...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Synthesis, Characterization and in vitro, in vivo and in silico Anti-Inflammatory Studies of the Novel Hybrid Based on Ibuprofen and 3-Hydroxy-Copalic Acid Isolated from Copaiba Oil (Copaifera multijuga)
A novel anti-inflammatory hybrid 3-ibuprofenyl-copalic acid (3-IbuCA) was synthesized from 3-hydroxy-copalic acid isolated from Amazonian copaiba oil (Copaifera multijuga Hayne), and the anti-inflammatory ibuprofen. After full characterization, several assays to verify its anti-inflammatory effects were performed in vitro, in vivo and in silico (molecular docking). Induced fit docking was performed to observe the interactions with the enzymes cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). In vitro tests of cytotoxicity and tumor necrosis factor (TNF)- α inhibition, and in vivo tests of pleurisy, protein expre...
Source: Journal of the Brazilian Chemical Society - July 3, 2020 Category: Chemistry Source Type: research

Additions and Corrections
Fingerprints are unique to each individual, contributing to human identification in forensic cases. The powder technique being widely used is considered one of the most important in latent fingermarks analysis. In this sense, the present work aimed to synthesize 1-thiocarbamoyl-4,5-dihydro-1H-pyrazoles and apply them as powder agents to develop latent fingermarks. The compounds were prepared from an effective and green synthesis via the condensation of chalcones with thiosemicarbazide in ethanol under microwave irradiation. Pyrazoles were tested and compared with a standard white powder (Sirchie ®) on glass surfaces us...
Source: Journal of the Brazilian Chemical Society - June 8, 2020 Category: Chemistry Source Type: research

Microwave Assisted Synthesis of Thiocarbamoylpyrazoles and Application as an Alternative Latent Fingermark Developers
Fingerprints are unique to each individual, contributing to human identification in forensic cases. The powder technique being widely used is considered one of the most important in latent fingermarks analysis. In this sense, the present work aimed to synthesize 1-thiocarbamoyl-4,5-dihydro-1H-pyrazoles and apply them as powder agents to develop latent fingermarks. The compounds were prepared from an effective and green synthesis via the condensation of chalcones with thiosemicarbazide in ethanol under microwave irradiation. Pyrazoles were tested and compared with a standard white powder (Sirchie ®) on glass surfaces us...
Source: Journal of the Brazilian Chemical Society - June 8, 2020 Category: Chemistry Source Type: research

Occurrence of Pesticides Associated to Atmospheric Aerosols: Hazard and Cancer Risk Assessments
Since the 1950s, pesticides have been used in agriculture. The increase in their consumption has been observed in recent years. In this work, it was determined the concentration of pesticides in the atmosphere of S ão Paulo and Piracicaba cities (sugarcane plantation site) and the hazard quotients and cancer risk caused by inhalation of these compounds were calculated. Twenty-three samples were analyzed and 34 pesticides associated to atmospheric particulate matter (with diameter equal to or less than 2.5 (PM 2.5) and 10 µm (PM10)) were investigated by gas chromatograpy-mass spectrometry (GC-MS). Fourteen comp...
Source: Journal of the Brazilian Chemical Society - June 8, 2020 Category: Chemistry Source Type: research

Synthesis, Characterization, and Synergic Photocatalytic Activity of Amorphous TiO2/Chitosan Carbon Microspheres
In this work, we report the synthesis and characterization of new amorphous graphene-like TiO2/chitosan carbon microspheres and its performance as photocatalyst. Four different carbon chitosan microspheres materials were obtained based on the distinctive procedure to incorporate TiO2 and TiOSO4 to chitosan structure by pyrolysis at 600 °C. Detailed characterizations were carried out using many different techniques, as thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), scanning electron miscroscopy/energy dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), X-ray ...
Source: Journal of the Brazilian Chemical Society - June 8, 2020 Category: Chemistry Source Type: research

Quantification of Arsenic, Cadmium, Mercury and Lead in Pineapple: Method Development, Validation and Evaluation of In-House Reference Materials
A method for quantification of arsenic, cadmium, mercury, and lead in pineapple using inductively coupled plasma-mass spectrometry (ICP-MS) was developed, validated, and used to test the homogeneity and stability of in-house reference materials. The method was tested at the regulation levels given by the Food and Agriculture Organization of the United Nations (FAO, 100 µg kg − 1). The mineralization conditions of the samples, in a microwave oven, were improved throughout the study of HNO3 and H2O2 concentrations, sample weight, time, and temperatures. The calibration was made by a gravimetric standard addition ...
Source: Journal of the Brazilian Chemical Society - June 8, 2020 Category: Chemistry Source Type: research