Pseudo-Univariate Calibration Based on NIR Spectroscopy in the Determination of Anthocyanins and Antioxidant Activity in Grape Juices
This work shows an alternative methodology based on a portable near-infrared (NIR) spectroscopy coupled to independent components analysis (ICA) in a pseudo-univariate calibration way to determine total anthocyanins (TA) concentration and antioxidant activity (AA) in whole grape juice. To this, the scores proportions more related to TA and AA were plotted against TA and AA obtained by its respective references methodology to build pseudo-univariate calibration models with correlation coefficients of 0.9699 and 0.9814, respectively. From the results, it is possible the suggestion that NIR spectra coupled to ICA enable to ov...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Thallium Associated with Manganese Ore Tailings in a Deactivated Mine in the Western Region of Bahia, Brazil
Thallium (Tl) is a rare metal with toxic effects notably harmful to human health and the environment. In this article, the natural occurrence of Tl was evaluated in a deactivated manganese mine located in the western region of Bahia, Brazil. The extraction procedure with aqua regia was used to dissolve the soil, sediment, and tailings samples. The Tl content was determined by differential pulse anodic stripping voltammetry (DPASV) and manganese (Mn) and iron (Fe) by flame atomic absorption spectroscopy (FAAS). The Tl levels ranged from 0.64 to 473 mg kg-1, triggering an alert since most of the samples (soil and sediment) a...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

In vivo and in vitro Volatile Constituents of the Flowers of Xylopia aromatica by HS-SPME/GC-MS
Xylopia aromatica (Lam.) Mart. (Annonaceae) is a typical species from the Brazilian cerrado that presents medicinal properties. The plant is distinguished by its large white flowers which produce a pleasant fragrance. X. aromatica is characterized by a wide range of medicinal application. These characteristics have motivated us to investigate the flowers volatile organic compounds (VOCs) via in vivo and in vitro protocols by a headspace solid-phase microextraction (HS-SPME) technique combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS). Four different fibers, extraction times and temperatures were the paramet...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Chemoenzymatic Synthesis of Apremilast: A Study Using Ketoreductases and Lipases
The key step in the chemoenzymatic synthesis of apremilast was to produce the chiral alcohol (R)-1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanol, (R)-3. Two enzymatic approaches were evaluated to obtain (R)-3, one using ketoreductases and the other lipases. Bioreduction of 1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanone (2), using ketoreductase KRED-P2-D12, led to (R)-3 with 48% conversion and 93% enantiomeric excess (ee). Kinetic resolution of rac-1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethyl acetate (rac-4), via hydrolysis reaction, with 20% of n-butanol, catalyzed by lipase from Aspergillus niger y...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Synthesis, Hypoglycemic Effect, Antimicrobial and Molecular Docking Studies of Organotin(IV) Complexes Derived From N-Phthalimido β-Amino Acid Derivatives
N-Phthalimido β -amino acid derivatives, 3-phthalimido-3(2-hydroxyphenyl) propanoic acid (P2HPA) and 3-phthalimido-3(2-nitrophenyl) propanoic acid (P2NPA) with new series of di- and triorganotin(IV) complexes (1-12) have been designed and synthesized. All the ligands and organotin(IV) complexes were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H, 13C, 119Sn) spectroscopy and electron ionization mass spectrometry (EI-MS). Synthesized ligands and complexes were screened to determine the antibacterial activity and results showed that the triorganotin(IV...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Synthesis, Characterization, and Application of Europium(III) Complexes as Luminescent Markers of Banknotes
In this work, three complexes were synthesized from the trivalent europium ion (EuIII), using the picrate anion (pic), and delta-valerolactam (DVL), epsilon-caprolactam (EPK), and oenantholactam (OEN). The synthesized complexes [Eu(pic)3 ·(DVL)3], [Eu(pic)3·(EPK)3], and [Eu(pic)3·(OEN)3] were studied as luminescent markers for application as security elements in Brazilian banknotes. All complexes showed red color emission with absorption at 397 nm and emission at 614 nm. Qualitative luminescence tests were performed on R$10, R$20 , R$50, and R$100 Brazilian banknotes. The complexes were applied on the ...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Chemical Constituents and Cytotoxic Activity of Rhinella jimi (Anura: Bufonidae)
Rhinella jimi toads (Stevaux, 2002) belong to the Bufonidae family, are endemic in the Brazilian Northeast and are commonly found during rainy periods. In general, amphibians of this family have in their poisons different metabolites that show a diversity of pharmacological activities. The isolation and identification of these compounds are of great importance, and techniques such as high-performance liquid chromatography coupled to mass spectrometry are widely used for the discovery of novel and known compounds in these poisons. For R. jimi poison, the ethyl acetate and methanolic extracts were obtained and thirty compoun...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Porosity of CHA Zeolite Driving the Formation of Polyaromatic Coke Species in the Methanol to Olefins Reaction
The pore size of the chabazite structure is exceptionally suitable for the methanol to olefins (MTO) reaction. The reaction has an induction period required for the formation of a hydrocarbon pool (HP), usually composed of aromatic compounds of different sizes. HP is alkylated by methanol and afterward cracked, leading to the formation of olefins. Despite the importance of HP, its formation and growth in size are exceedingly dependent on the porosity of the catalyst. The ideal is that the formed HP remains stable throughout the reaction because the growth in its size causes blockage of the small catalyst pores, decreasing ...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Incorporation of Fluorescent Dyes in Electrospun Chitosan/Poly(ethylene oxide)
Polymeric films have been increasingly investigated due to the ease of miniaturization and integration in several sensor devices. Films obtained from the electrospinning technique have a controlled diameter and homogeneity, and substances can be incorporated into the polymeric network. Electrospinning fiber of chitosan (Ch) and poly(ethylene oxide) (PEO) was obtained from solutions prepared at different concentrations in acetic acid, and varying the distance and the voltage applied. The obtained films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scan...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Astaxanthin Recovery from Shrimp Residue by Solvent Ethanol Extraction Using Choline Chloride:Glycerol Deep Eutectic Solvent as Adjuvant
The present study investigated the use of choline chloride:glycerol deep eutectic solvent as an adjuvant for tuning the ethanol extraction of astaxanthin from Litopenaeus vannamei processing residues. The adjuvant concentration did not show a clear trend on the total carotenoid, however, the addition of adjuvant proved to be advantageous in the ultrasound-assisted experiments. In order to establish a balance between total carotenoid and productivity, an operational condition with ultrasound, 5% (m/v) choline chloride:glycerol and 10 min of incubation was selected, which provided 737.69 µg g-1 total carotenoids and 32...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Design, Synthesis and Antifungal Activity of New Schiff Bases Bearing 2-Aminothiophene Derivatives Obtained by Molecular Simplification
Seventeen Schiff bases bearing 2-aminothiophene derivatives were designed and synthesized using molecular simplification. The resulting compounds (4a-4q) were evaluated for their in vitro antifungal activity against dermatophytes. Prediction of their druglikeness and pharmacokinetic properties, establishment of their structure-activity relationships (SAR), and cytotoxic evaluation of the most active compounds were performed. Using an eco-friendly procedure, microwave assisted synthesis resulted in compounds in good yields (35-85%). Compounds 4a-4q presented good druglikeness and pharmacokinetic profiles and no cytotoxicity...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

New Pair of 2-Amino-naphthoxazoles Derived from β-Lapachone: Synthesis, Spectral Evaluation and Crystal Structure
This work describes a novel synthetic route for obtaining 2-amino-naphthoxazoles derived from β -lapachone, which consists of a condensation reaction between β -lapachone and thiourea in a basic medium. This synthetic approach can be seen as a potential route for obtaining 2-amino-oxazoles from quinones. The obtained amino-naphthoxazoles were characterized by spectroscopic techniques and the crystal structure of one of them was resolved by X-ray diffraction. The experimental results were compared to that obtained through density functional theory (DFT) calculations, revealing high correlation coefficients. (Sourc...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Electrochemical Preparation and Evaluation of Cytotoxic Activity of Methoxyl-oxo-biseugenol, a New Oxidized Derivative of Biseugenol
In this study, the electrosynthesis of biseugenol in MeOH afforded one new oxidized derivative, which was characterized as methoxyl-oxo-biseugenol (MOB) by nuclear magnetic resonance (NMR) and electrospray ionization-high resolution mass spectrometry (ESI-HRMS) analysis. Since biseugenol was previously described as a cytotoxic natural product, MOB was also tested against tumoral cells B16F10-Nex2 (murine metastatic melanoma) and SKMEL-25 (human metastatic melanoma) as well as against non-tumoral cells M Ø Raw 264.7 (murine macrophage immortalized) and HUVEC (human umbilical endothelium). As results, MOB showed inhib...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Effects of Polycyclic Aromatic Hydrocarbon Pendant-Armed Ligands on the Catecholase Activity of Dinuclear Copper(II) Complexes
Herein, we present three new binuclear copper(II) complexes containing different polycyclic aromatic hydrocarbons, able to catalyze the oxidation of 3,5-di-tert-butylcathecol, a model substrate for catechol oxidase. The ligands and complexes were successful characterized in solid and solution states. The structure of C1 was determined by X-ray crystallography and it contains a [CuII2(L1- µ-phenoxo)(OAc)(H2O)2] unit, with two coppers in a pyramidal square geometry and a large distance of 3.715 Å between the copper(II) centers. All complexes (C1, C2 and C3) were found to be effective catalysts in the oxidation of...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

An Online Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry Method for the Analysis of Parabens in Urban Waters
This study findings included the detection of parabens in samples in São Carlos. (Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Iron Nitrate Modified Cotton and Polyester Textile Fabric Applied for Reactive Dye Removal from Water Solution
In this work, we investigated the use of cotton scraps in natura and modified with iron nitrate, in the adsorption of one of the main water contaminants of the textile industries, the reactive black dye. Special attention was paid to the appropriate destination of the spent adsorbent, in compliance with the precepts of the circular economy. Cotton and polyester are excellent candidates for adsorbents and are produced on a large scale worldwide, but fabric wastes do not yet have a well-established method of application. We found that fabrics containing different types of fibers or colors maintain the ability to remove dye. ...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Use of Paper Spray Mass Spectrometry for Determining the Chemical Profile of Green Cavendish Banana (Musa AAA) Peel and Pulp Flours and Evaluation of Its Functional Potential
Green Cavendish banana peel and pulp flours were obtained by three drying methods: oven dryer at 70 °C; air fryer at 180 °C and domestic oven at 180 °C, being the latter two new possibilities. Bioactive constituents using paper spray ionization mass spectrometry (PS-MS), phenolic identification and quantification by ultra-performance liquid chromatography with UV-Visible detection (UPLC/UV-Vis) and antioxidant capacity were evaluated. Phenolic acids showed distinct thermal stability between the treatments. Gallic acid was the predominant compound, ranging from (29.56 to 1211.74 mg 100 g-1) and had higher concen...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

A Catalysis Guide Focusing on C–H Activation Processes
From the recent development of catalytically controlled C-H activation with amenable synthetic routes obviating many challenges, the demand for this strategy has raised significantly to perform complex organic transformations. The impact of the achieved results in both homogeneous and heterogeneous catalysis reflects its efficacy in modern synthetic chemistry. A consolidated report and guidance of the methodologies involved in the previous and ongoing research in this domain would be very useful for the researchers to focus on more specific and selective C-H activation reactions to access desired complex molecular scaffold...
Source: Journal of the Brazilian Chemical Society - April 30, 2021 Category: Chemistry Source Type: research

Synthesis of a Homologous Series of Trialkyl Arsines (C3-C12) and Applications of Arsenic Triiodide as a Synthetic Precursor
This work presents some modifications in the post-synthetic processing for a classical arsenic reagent: AsI3. In comparison with the widely used analog, the trichloride, arsenic triiodide presents several advantages such as low toxicity, air stability, and low volatility. It was used as a synthetic precursor in the preparation of a variety of arsenic(III) derivatives like arsines, arsenites, and thioarsenites. Besides that, AsI3 was submitted to a diversity-oriented Grignard reaction in the preparation of a homologous series of trialkyl arsines ranging from AsC3H9 to AsC12H27. The series was analyzed by comprehensive two-d...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Efficient Synthesis and Antimicrobial Activities of Long Alkyl Chain Trifluoromethyl-1H-pyrazol-1-(thio)carboxamides and Trifluoromethyl-1H-pyrazol-1-yl-thiazoles
The synthesis of 3-alkyl-5-trifluoromethyl-1H- pyrazole-1-carboxamides, 3-alkyl-5-trifluoromethyl-1H-pyrazole-1-thiocarboxamides, and 2-(3-alkyl-5-trifluoromethyl-1H-pyrazol-1-yl)-thiazoles derivatives are reported. [3 + 2] cyclocondensations for a series of long alkyl chain 1,1,1-trifluoro-4-methoxyalk-3-en-2-ones and semicarbazide or thiosemicarbazide were carried out in ethanol, an eco-friendly medium. The series of trifluoromethyl-1H-pyrazol-1-yl-thiocarboxamide following a [3 + 2] cyclocondensation with 2-bromoacetophenone were converted into two series of 2-(3-alkyl-5-trifluoromethyl-1H-pyrazol-1-yl)-thiazoles. Good ...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Voltammetric Generation and Kinetic Stability of Nitro Anion Radical from Nitrofurazone in Ionic Liquids
The nitrofurazone (NF) electrochemical reduction has been studied by cyclic voltammetry (CV) and square wave voltammetry (SWV) in non-aqueous medium using three different ionic liquids (IL): BMImTf2N, BMImBF4 and BMMImTf2N, having a carbon fiber microelectrode as working electrode. In all of them, two reversible cathodic peaks were recorded for NF. Under higher frequency values, only one reversible cathodic peak was registered. The systems reversibility could also be observed by CV, since a reversible redox couple was registered for this reduction. The systems reversibility with product and reagent adsorptions on the elect...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Agroindustry Residues as a Source for Cellulose Nanofibers Production
Our study was motivated by the large amount of crop residues produced in Brazil, which represent underutilized waste biomass and a serious threat to the environment because of the landfilling. For example, even though the corn crop is not popular in Brazil, it is produced in the area of around 18-20 million hectares with an average production of 5-6 t ha-1. That is the reason to seek for the crop residues value-added applications as proposed in the present study. Four Brazilian crop waste biomass: orange bagasse, corn husks, sugarcane straw and coffee residues were used for cellulose nanofibers (CNF) production. CNFs were ...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

First-Principles Calculations of a New Semi-Conductive Carbon Allotrope Named ABF-Carbon
Carbon is an extremely versatile element and can generate a plethora of structures with distinct properties. Proposing new possible metastable allotropic structures for carbon has been the subject of increasing interest over the past few years. In this contribution, we present a new carbon allotrope, named ABF-Carbon, based on the connection of spiropentadiene molecular motif and sp3 carbon atoms. This new structure is a metastable carbon allotrope formed by 6 carbon atoms, being 2 sp2 and 4 sp3, in a body-centered tetragonal with space group (space group 119) and point group . By first-principles calculations using the de...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Improving Photoluminescence Quantum Yield of CdTe Quantum Dots Using a Binary Solvent (Water + Glycerin) in the One-Pot Approach Synthesis
The present work describes the comparison of the optical and structural properties between CdTe quantum dots (QD) synthesized in water and in the binary solvent (water + glycerin) via one-pot approach synthesis. The optical properties of the nanocrystals obtained with different synthesis parameters were characterized by UV-visible and photoluminescence spectroscopies. The structural chracterization were performed by Fourier transform infrared spectroscopy (FTIR), zeta potential, size-distribution by dynamic light scattering (DLS), X-ray diffraction (XRD), and also by high-resolution transmission electron microscopy (HRTEM)...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

[5]Helicene-Scaffold Fluorescence Sensing for Selective Detection of Au3+ Ions and Gold Nanoparticle
A new quenching fluorescence sensor (MDP) with high productivity was easily synthesized from a [5]helicene anhydride derivative and propargyl bromide. This MDP sensor has significant photophysical properties, including high fluorescence emission and a large Stokes shift, and it exhibits selectivity and an excellent detection response in distinguishing Au3+ ions from interfering metal ions in aqueous solution. The limit of detection of the sensor were determined to be 0.16 µmol L-1 or 32.0 ppb. Stoichiometric binding between the MDP and Au3+ ions was found to occur at a 1:2 ratio. Additionally, the MDP sensor shows an...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Alternative Approaches Applied to Inductively Coupled Plasma Techniques: Multi-Flow and Two-Flow Calibration
Multi-flow calibration (MFC) is based on monitoring the analytical signal from a single calibration standard solution at several different nebulization gas flow rates (Q), which normalizes plasma conditions and minimizes matrix effects. In the present study, MFC was evaluated, for the first time, applied to inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) to analyze different and complex-matrix samples. Al, As, Cd, Cr, Cu, Mn, Pb, and Zn were determined by ICP OES, while As, Cd, Co, Cu, Hg, Mo, Mn, Ni, Se, Sb, Pb, and V were determined by ICP-MS. M...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Reduced Graphene Oxide-Cadmium Sulfide Quantum Dots Nanocomposite Based Dispersive Solid Phase Microextraction for Ultra-Trace Determination of Carbamazepine and Phenobarbital
This research presents a fast, sensitive, and selective ultrasound-assisted dispersive solid phase microextraction technique for simultaneous preconcentration and determination of ultra-trace amount of carbamazepine and phenobarbital. Reduced graphene oxide sheets decorated with cadmium sulfide quantum dots was synthesized, characterized, and used as a high capacity adsorbent. A high performance liquid chromatography with UV detector (HPLC-UV) instrument with 58:42 composition of methanol:acetic acid/acetate buffer (pH = 5; 0.05 mol L-1) as the mobile phase and set on the wavelength of 230 nm was used to separate and quant...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Development and Validation of a Gas Chromatographic Method for the Quantification of Minor Alkaloids in Cocaine
The quantification of minor alkaloids in seized cocaine can provide information for drug profiling and law enforcement initiatives. This work presents the development and validation of an analytical method to quantitate minor alkaloids in cocaine samples using gas chromatography with flame ionization detector, after derivatization. The method was validated in accordance with the ISO/IEC 17.025:2017 requirements. The calibration was linear (determination coefficient (R2) ≥ 0.998), ranging from 1.0 to 3,500 mg L-1 for all target analytes with suitable selectivity and precision (relative standard deviation lower than 10%)....
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Thermal and Catalytic Fast Pyrolysis of Oily Extracts of Microalgae: Production of Biokerosene
Three different microalgae species, Desmodesmus sp., Nannochloropsis oculata and Halamphora coffeaeformis were grown under controlled conditions. The resulting dry biomass was characterized by TG-DTA (thermogravimetry-differential thermal analysis) and extracted with three solvents having different polarities. The extracts gross mass yields varied from 2% using n-hexane to 23% (or 74% when subtracting the volatiles and ashes) when using methanol-chloroform whatever the microalgae species. Fourier transform infrared (FTIR) spectra of all extracts suggested the presence of fatty esters and acids. The extracts were pyrolyzed ...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

In silico Evaluation of Cucurbit[6]uril as a Potential Detector for Cocaine and Its Adulterants Lidocaine, Caffeine, and Procaine
Illicit drugs and their trafficking require worldwide efforts in investigation, detection, and control. Colorimetric tests are often applied to identify drugs. Cocaine has some well-known adulterants that can provide a false positive response. Cucurbit[6]uril (CB[6]) has been suggested as a potential detector for cocaine and other illicit drugs. This work uses in silico methods to evaluate the use of CB[6] to detect cocaine and these interfering substances. More specifically, this work analyzes different possibilities of CB[6] complexation with cocaine, lidocaine, caffeine, and procaine and compares the results achieved fo...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Bioactive Bioflavonoids from Platonia insignis (Bacuri) Residues as Added Value Compounds
Platonia insignis fruit, popularly known as bacuri, is traditionally used in folk medicine for its anti-inflammatory and antioxidant properties. Therefore, this study determined the chemical composition and biological activities of the bacuri ’ s shell and seeds extracts, considered residues from its consumption and industrial uses. Four biflavonoids (GB-2a, GB-1a, morelloflavone, and volkensiflavone) were identified in the extracts by high-performance liquid chromatography-diode array detection (HPLC-DAD), liquid chromatography tandem mass spectrometry (LC-MS/MS), and liquid chromatography-solid phase extraction-nuc...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Device for Streptavidin Detection Using LSPR and Electrochemical Transductions on the same Platform
Research in biosensing currently occupies an important role among biomolecular detection techniques, especially with respect to medical diagnoses. Is this sense, the development of biosensors based on the localized surface plasmon resonance (an optical transducer) or electrochemical transductions have been highlighted. However, optical and electrochemical detection working together enable more versatile detections in biosensing. Thus, we propose a dual sensor, which incorporates these two mechanisms on the same platform. The sensor shared the same transducer that was based on a glass-indium thin oxide (ITO) surface covered...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Identification of Potential Human Protein Targets for Soybean Isoflavones
Soy isoflavones have been reported as endocrine disruptors due to their ability to modulate the activity of estrogen receptors (ERs) in mammals; however, its ability to modulate other metabolic pathways is not entirely clear, which makes it necessary to identify new pharmacological targets that interact with these compounds present in soybean. In this work, a virtual screening was executed to identify potential targets of nine soy isoflavones, employing human proteins target from PharmMapper. The best 25 fit scores were selected and prepared for AutoDock Vina docking protocols. The results suggest that equol, daidzein and ...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Synthetic Studies toward (−)-Cleistenolide: Highly Stereoselective Synthesis of New γ-Lactone Subunits
This study describes the stereoselective synthesis of two new γ -lactones in 6 and 3 steps and 19 and 32% yield, respectively, directed toward the total synthesis of the natural product ( − )-cleistenolide. The starting material was an enantiomerically pure diacetonide diol, derived from d-mannitol with the required stereocenters for ( − )-cleistenolide synthesis. γ -Lactone syntheses were based on highly selective protection and deprotection of hydroxyls from d-mannitol. The formation of γ -lactone rings was the culmination of this approach, made possible by a Horner-Wadsworth-Emmons Z-olefin...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

The Stabilization of Asphaltenes in Different Crude Fractions: A Molecular Approach
The conditions of petroleum extraction may allow asphaltenes to precipitate, causing deposition that clogs wells, pipes and equipment, consequently reducing productivity. In this work, the solubility parameters and precipitation onset of polar fractions of heavy crudes from Brazilian fields were estimated using a simplified system of n-heptane/toluene mixtures. Asphaltenes were extracted by two different methods with regard to pressure and temperature. The samples were physically and chemically characterized, and both density (1053-1159 kg m-3) and molecular weight (1176-5316 g mol-1) were estimated based on the density of...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Study of the CuII Affinity by Three Chelating Agents of Biological Interest: TPEN, TRIEN and Et2DTC
Copper is an important micronutrient, and it is present in some protein structures, as well as participate in several important biological processes. Due to its importance, some ligands are used and studied like carriers of copper in the biological systems. This work has investigated the affinity of CuII by three ligands of biological interest: N, N, N, N ’ -tetrakis (2-pyridilmethyl) ethylenediamine (TPEN), triethylenetetramine (TRIEN), and diethyldithiocarbamate (Et2DTC), used for this purpose. The studies were performed by evaluating the CuII d-d band when complexed with these three ligands. The CuII d-d band in a...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Validation of an UHPLC-MS/MS Method for the Determination of Malachite Green, Leucomalachite Green, Crystal Violet, and Leucocrystal Violet in Shrimp, Fish, and Salmon Muscle Using a Modified QuEChERS Approach
A quantitative and confirmatory method for detecting the presence of triphenylmethane dyes in shrimp muscle using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and a quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction approach was validated. The method exhibited linearity and selectivity and the coefficient of determination (R2) was higher than 0.95 for all studied analytes. Limits of detection (LODs) varied from 0.32 to 0.44 µg kg-1 and the limit of quantification (LOQ) was determined to be 0.5 µg kg-1 for all studied analytes. The trueness, precision, dec...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Synthesis, in silico Study and Antileishmanial Evaluation of New Selenides Derived from 7-Chloro-quinoline and N-Phenylacetamides
This study describes a virtual screening performed for two series of selenides (28 compounds), derived from N-phenylacetamides chlorides and 7-chloro-quinoline, to determine their potential for leishmanicidal activity against Leishmania amazonensis and Leishmania donovani. Seven compounds were predicted as potential leishmanicides; therefore, they were synthesized from elemental selenium, as a precursor for the production of NaHSe, and subsequent reactions with 4,7-dichloro-quinoline and N-phenylacetamides chlorides were performed. The compounds were characterized by infrared (IR), 1H and 13C nuclear magnetic resonance (NM...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Microwave-Assisted Acid Digestion: Evaluation of Reaction Vessel Design and Performance
Nowadays, microwave-assisted procedures using closed vessels with thermal, chemical, and mechanical resistance are the state-of-the-art for efficient digestion of samples. Safety issues related to sample reactivity should be considered and analytical throughput is also a critical parameter. The choice of a specific vessel for a target application is not trivial and simple experiments are presented here for rice flour and bovine liver samples to illustrate effects of vessel design on digestion performance. Despite using the same heating program, the residual carbon contents varied from 22 to 67% to bovine liver digests and ...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Structural Study of Wheat Gliadin in Different Solvents by Spectroscopic Techniques
Physicochemical properties of gliadin in different solvents (dimethyl sulfoxide (DMSO), H2O, and aqueous ethanol) and pH (9.8, 6.8, and 1.2) were investigated using dynamic light scattering (DLS), zeta potential (ZP), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Gliadin-DMSO and gliadin-deionized water (H2O) (pH 9.8) showed a lower size distribution, whereas samples solubilized in 60% aqueous ethanol presented a lower size distribution only at pH 1.2. ZP analysis showed that gliadin-H2O (pH 9.8) was the most stable evaluated system. ZP results of gliadin-DMSO indicated an unstable sy...
Source: Journal of the Brazilian Chemical Society - March 29, 2021 Category: Chemistry Source Type: research

Metal Distribution in the Environmental Compartments of Manguaba Lagoon (Alagoas State, Brazil)
The metal concentrations in water, sediments and mollusks (Tagelus plebeius) of the Manguaba Lagoon and the influence of humic substances from water and sediments in the distribution of these metals were investigated in this work. The mean metal concentrations in water were: Mg (89.0 ± 0.11), Ca (32.0 ± 0.10), Fe (0.97 ± 0.02), Mn (0.52 ± 0.01), Zn (0.33 ± 0.10) and Pb (0.22 ± 0.02) mg L-1. The Pb concentrations were above the Brazilian legislation limit. All sediment data were below maximum limit established by the National Council for the Environment (CONAMA, Brazil) of the Minis...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

PhotoMetrix UVC: A New Smartphone-Based Device for Digital Image Colorimetric Analysis Using PLS Regression
A novel free PhotoMetrix UVC is proposed for both the operation of a universal serial bus video camera (UVC) and multivariate image analysis, allowing a full solution for point-of-use analysis. A UVC was placed in an open-source 3D-printed chamber illuminated by a white light-emitting diode (LED) with controlled intensity of light. The digital images captured were converted into red, green, and blue (RGB) histograms, and regression models were used within the app. As a proof-of-concept, four adulterants in raw milk samples were determined. The coefficient of determination (R2Cal) for all models was higher than 0.99, and no...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Perovskite-Type Oxides La0.6M0.4Ni0.6Cu0.4O3 (M = Ag, Ba, Ce) towards the Oxygen Reduction Reaction (ORR) in Alkaline Medium: Structural Aspects and Electrocatalytic Activity
In this work, La0.6M0.4Ni0.6Cu0.4O3 (M = Ag, Ba, and Ce, denoted as LANC, LBNC, and LCNC, respectively) electrocatalysts were synthesized by the Pechini method at 1023 K for two hours in air. Rietveld refinement allowed the identification of the crystallographic phases present in all oxides. The electrocatalytic performance of these oxides towards the oxygen reduction reaction (ORR) was examined in alkaline medium by rotating disk electrode (RDE) technique and scanning electrochemical microscopy (SECM) in the redox competition mode. The results indicate that the best performance was found with the LANC electrocatalyst prep...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Inhibition of Acetylcholinesterase by Coumarin-Linked Amino Acids Synthetized via Triazole Associated with Molecule Partition Coefficient
A previous study for the identification of acetylcholinesterase (AChE) inhibitors demonstrated that the hybrid between tyrosol, the 1,2,3-triazole nucleus, and the coumarin group, namely 7-({1-[2-(4-hydroxyphenyl)ethyl]-1H-1,2,3-triazol-4-yl}methoxy)-4-methyl-2H-chromen-2-one (10), has a high enzyme inhibitory activity. Here, we synthesized analogues of 10 via triazole with pharmacophoric groups represented by tyrosine, phenylalanine, tryptophan, and glycine in addition to evaluating the impact of coumarin-linked amino acids on AChE inhibition. We obtained eight triazoles, six of which are undescribed. In general, the pres...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Compatibility by a Nonisothermal Kinetic Study of Azathioprine Associated with Usual Excipients in the Product Quality Review Process
Azathioprine is an immunosuppressive drug for several inflammatory disorders. Due to its clinical relevance, to explore the solid-state properties for excipient compatibility in the product quality review process is essential. Fourier transform infrared spectroscopy, powder X-ray diffraction and thermal analysis (thermogravimetry/derivative thermogravimetry (TG/DTG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC)) were applied. The compatibility studies evidenced that starch pregelatinized, colloidal silicon dioxide, and talc are fully compatible with azathioprine. However, stearic acid, m...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Synthesis of Hydroxybenzodiazepines with Potential Antioxidant and Antifungal Action
Benzodiazepines derivatives are nitrogen heterocyclic compounds that have various industrial, synthetic, and medicinal applications. Therefore, its potential fully justifies every effort towards the improvement of new, selective, and competent production of these heterocyclic compounds. The novelty of this study encompasses the synthesis of new hydroxylated analogs of 1,5-benzodiazepine together with the evaluation of their biological potential as antioxidants and antifungals candidates. Additionally, the reported antifungal activity against fungi of the Sporothrix schenckii complex inaugurates an unprecedented property fo...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Multivariate Optimization of Extraction Variables of PAH in Particulate Matter (PM10) in Indoor/Outdoor Air at Campos dos Goytacazes, Brazil
This study aims to evaluate the presence of outdoor and indoor PAH in 10 µm particulate matter (PM10) at one university in Campos dos Goytacazes. PM10 samples were collected from January to November 2018. Samples were extracted using an ultrasonic probe and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The ideal extraction conditions (3 min; 150 W ; 50 mL) were defined by 23 full factorial design. The analysis showed a significant PM10 level increase (23.19 to 34.50 µg m-3 in outdoor, and 15.15 to 31.66 µg m-3 in indoor samples) and higher total PAH concentration in the harvesting s...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Magnetic and Mesoporous Silica-Niobia Material as Modifier of Carbon Paste Electrode for p-Nitrophenol Electrochemical Determination
In the present work, the sol-gel synthesis method was employed as strategy to obtain a magnetic and mesoporous silica-niobia material. The planned synthesis was based on the hetero-condensation of niobium and silicon alkoxide precursors, in the presence of spherical magnetite particles. The resulting material presented interesting characteristics such as magnetism, large mesopores, in the range from 20 to 50 nm, and 68 m2 g-1 of surface area. These features allowed its use as modifier of carbon paste electrode for p-nitrophenol determination, since niobia has never been used in electrochemical sensors for the determination...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Single-Layered Paper-Based Microfluidic Devices Made by Paint-Spraying Technique with Great Barrier Resistance for Colorimetric Assays
The single-layered paint-spraying paper based microfluidic devices (sp- μ PADs) have been for the first time integrated with the colorimetric assay. The polymethyl methacrylate (PMMA) board was applied as the mask instead of the iron mask, reducing the power requirement of the cutting machine. The paint was sprayed into the paper, which blocked the pores of the paper and constructed the hydrophobic barrier on the paper. The paint barrier was highly resistant to the various kind of chemicals and the minimum channel dimensions was 1.4 mm. By using the PMMA masks with different designs, the sp- μ PADs with different des...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Evaluation of the Direct Interaction between Amino Acids and Glutathione-Coated CdTe Quantum Dots and Application in Urinalysis for Histidine Determination
The present work aimed to direct amino acid (AA) sensing by quantum dots (QD) and development of an analytical method for potential fast clinical tests. Notably, AA with a positive charge or neutral polar chains, namely L-histidine (His) and L-threonine (Thr), responded to glutathione-coated CdTe (GSH-CdTe) ( Δ F ≤ 90%, variation of fluorescence intensity). However, in ammoniacal buffer (0.25 mol L-1) at pH 8.0, 2.2 nm GSH-CdTe responded only to His. Static quenching with complex association constant (Ksv) varying from 2.81 to 0.94 (10 L mol-1) as well as van der Waals forces and/or hydrogen bonding were predicted...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research