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Complementary Performance of Organoselenides and Organotellurides as Antimicrobials Agents
Fungi and bacteria are well-known pathogens for plants, fruits, and animals, including humans. In this context, the prospection of antimicrobial agents is crucial to provide new alternatives for the treatment of microbial diseases. Hence, selenium- and tellurium-containing compounds are underexploited and herein, antimicrobial activity of several organochalcogenated compounds was evaluated against Gram-negative and Gram-positive bacteria and fungi. A direct comparison between Se- and Te-containing compounds was performed, as well as structure-activity relationship studies. Among assayed compounds, secondary Se-amines LQ16 ...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Sample Preparation Using TMAH and Nitric Acid for Multielement Determination in Crustacean Samples by MIP OES
This study proposes a simple sample preparation procedure using tetramethylammonium hydroxide (TMAH) and nitric acid (HNO3) to determine Cr, Cu, Fe, K, Mg, Mn, and Zn concentrations in shrimp (Macrobrachium amazonicum) and crab (Ucides cordatus) samples from the Amazon region by microwave-induced plasma optical emission spectrometry (MIP OES). The sample solubilization was carried out employing TMAH and HNO3 using an ultrasound bath and a thermostatic water bath. The accuracy of the proposed procedure was performed using microwave-assisted digestion as comparative method. Certified fish protein reference material (DORM-4) ...
Source: Journal of the Brazilian Chemical Society - March 1, 2021 Category: Chemistry Source Type: research

Antileishmanial Acetylene Fatty Acid and Acetogenins from Seeds of Porcelia macrocarpa
In the present work five acetylene derivatives (1-5), including three unknowns (1, 3 and 4), were isolated from seeds of Porcelia macrocarpa (Annonaceae). The structures of isolated compounds were determined as docos-13-yn-21-enoic acid (1), 3-hydroxy-4-methylene-2-(eicos-11 ’ -yn-19 ’ -enyl)but-2-enolide (2), 3-hydroxy-4-methylene-2-(octadec-9 ’ -yn-17 ’ -enyl)but-2-enolide (3), 3-hydroxy-4-methylene-2-(hexadec-7 ’ -yn-15 ’ -enyl)but-2-enolide (4), and (2S,3R,4R)-3-hydroxy-4-methyl-2-(eicos-11 ’ -yn-19 ’ -enyl)butanolide (5) by analysis of nuclear magnetic resonance (NMR) and electrospray ionization high-r...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Yellow Mombin (Spondias mombin L.) Seeds from Agro-Industrial Waste as a Novel Adsorbent for Removal of Hexavalent Chromium from Aqueous Solutions
The objective of this study was to develop a low-cost and eco-friendly adsorbent from agro-industrial waste for the removal of hexavalent chromium in the aqueous medium. The adsorbent (BMC) produced from yellow mombin (Spondias mombin L.) seeds was characterized by the determination of the chemical composition, thermal analysis (thermogravimetric (TG) analysis and differential thermal analysis (DTA)), Fourier transform infrared spectroscopy (FTIR), pH in suspension and determination of the point of zero charge (PZC). The presence of proteins, fats and carbohydrates (15.690, 1.004, and 73.706%, respectively) suggests that t...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Crystal Structure and Hirshfeld Surface Analysis of 1,4-Pentadien-3-one, (1E,4E)-1,5-diphenyl-2-(2,4-dinitrophenyl)hydrazone
The compound 1,4-pentadien-3-one,(1E,4E)-1,5-diphenyl-2-(2,4-dinitrophenyl)hydrazone presents the molecular formula C23H18N4O4 and was prepared in an undergraduate laboratory. The hydrazone was synthesized from the condensation between dibenzalacetone and 2,4-dinitrophenylhydrazine (DNPH) and crystallized employing water/acetone liquid-liquid diffusion. The structure presents three aromatic rings connected by an unsaturated Y-shaped system. Dinitro substituted and one of the other aromatic rings are 15 º out of a coplanarity, while the other phenyl group is almost orthogonal to the first (89º). The only observed classica...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Aqueous Extract of Cumaru (Dipteryx odorata) Seeds as Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Solution
The corrosion inhibition of mild steel by aqueous extract of cumaru (Dipteryx odorata) seeds and its high molecular weight fraction (HMWF) was investigated in 1 mol L-1 HCl solution. The study was carried out through gravimetric essays, open circuit potential measurements, anodic and cathodic polarization curves and electrochemical impedance analyses, as well as morphological analysis of the mild steel by scanning electron microscopy. Gravimetric tests showed that the inhibition efficiency (IE) increased with immersion time and inhibitor concentration, reaching 98% of IE using 100 mg L-1 of the HMWF, after 6 h immersion ti...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

An Alternative Description for the Electronegativity Difference in Binary Ionic Solids
We are introducing an alternative analytical expression to the electronegativity difference ( ∆ χ ) as a function of the charge ge, g is the charge factor, the fraction of the electronic charge devoted to the bond and e the elementary charge, the packing factor (p) and the effective atomic number (Zeff) of binary ionic solids, by using the very basic Coulomb interaction, modified by the introduction of p, and the relationship between the electric dipole moment ( µ) and ∆ χ in Debye units. When compared to the Pauling ’ s, Gordy ’ s, Allred-Rochow ’ s and Allen ’ s scales, our calculations deviate around 10%...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Theoretical Study of the Reactivity of Phenyl Radicals Toward Enol Acetates
Arylation reactions are an important class of reactions and allow the synthesis of natural and synthetic products. Despite the efficient, but high cost and toxic methodologies involving transition metals, radical arylations have gained importance after the advent of photoredox catalysis. Arylation of enol acetates is an important tool for obtaining aryl ketones but the scope of the reaction is limited to the pattern of substitution at phenyl radical and α -carbon of the enol. Theoretical calculations ((U)BHandHLYP/6-311G**) show that the polar effect is the key factor in this reaction. A good correlation of calculated rat...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Evaluation of the Seasonality and Extraction Method on the Polar Extracts of Croton grewioides Baill. by Chromatogram Fingerprinting and Isolation of a New Triglycosylated Flavonoid
Croton grewioides Baill. popularly known as “ canelinha ” or “ canelinha-de-cheiro ” has been used for the treatment of influenza, antitussive, febrifuge and headache; however, the study of its phytochemical composition is limited. The aim of this study was to investigate the effect of the extraction method and seasonality through leaf extracts of four accessions of Croton grewioides by fingerprint chromatograms aided by principal component analysis to analyze the differences and similarities among the samples. We aimed also to provide chemical characterization of isolated secondary metabolites using semi-prepara...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Er3+/Yb3+-Doped GdVO4 Obtained by the Non-Hydrolytic Sol-Gel Route and Potential Application as Up-Conversion Thermometer
The properties of lanthanides allow them to be used as contrast agents for magnetic resonance imaging, thereby helping to differentiate between tissues, organs, and pathologies more efficiently. Lanthanides contain thermosensitive energy levels that aid identification of cancer and healthy cells. This work investigates the GdVO4 matrix obtained by the non-hydrolytic sol-gel methodology and doped with the lanthanide ions Er3+ and Yb3+ at a 1:1 molar ratio. The efficiency of the optical parameters was analyzed on the basis of the Er3+ green emission after excitation in the infrared region, namely 980 nm. The temperature-depe...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Characterization, Source Apportionment and Health Risk Assessment of PM2.5 for a Rural Classroom in the Amazon: A Case Study
In this study, indoor and outdoor PM2.5 levels were measured in a classroom in Iranduba, and the PM2.5 exposure effects on student ’ s health were calculated. High indoor PM2.5 concentrations and high indoor-to-outdoor ratio values indicated particle accumulation within the classroom. The high percentage of black carbon (10%) in the dry season revealed the influence of burning processes on PM2.5 composition. Se, S, and Pb had an enrichment factor> 5, indicating that there is an important source for these elements in the city. The positive matrix factorization (PMF) model indicated soil resuspension, burning processes ...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Preparation of Poly(3-hydroxybutyrate-b-ε-caprolactone) by Reactive Extrusion and Production of Electrospun Fibrous Mats
Poly(3-hydroxybutyrate) (PHB) has been proposed to be a potential candidate to be used as biomaterial. However, its poor processability, high brittleness and rigidity have limited its applicability. Transesterification reactions with poly( ε -caprolactone) (PCL), one of the most promising biomedical materials, emerge as an attractive alternative to improve its mechanical properties. In this work, poly(3-hydroxybutyrate-b- ε -caprolactone) (PHB-b-PCL) was prepared straightforwardly by transesterification of the parent homopolymers by reactive extrusion in the presence of stannous octanoate. After purification by solvent f...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Morita-Baylis-Hillman Reaction with 7-Chloroquinoline Derivatives-New Compounds with Potential Anticancer Activity
Morita-Baylis-Hillman adducts (MBHA) is a class of polyfunctional molecules that has been standing out due to their versatility and expressive biological activities. Therefore, this paper describes the synthesis and antiproliferative activity of some new MBHA/7-choroquinoline hybrids. The Michael acceptors were obtained starting from 4,7-dichloroquinoline which were submitted to the Morita-Baylis-Hillman reaction with ortho, meta and para-nitrobenzaldehyde. The in vitro screening of the synthetized MBHA against NCI-H292, HCT-116 and MCF-7 cancer cells suggests the influence of the spacer chain in its inhibition potential. ...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Mineral Nutrients and Plant-Fungal Interaction in Cocoa Trees (Theobroma cacao L.)
In this study, the concentrations of mineral nutrients in healthy leaves and in leaves of vegetative broom of the cocoa plant were determined, and the relationship between the disease and the nutritional composition of the leaves was assessed. The samples were analyzed using the wet digestion method and the concentrations were determined by inductively coupled plasma optical emission spectrometry and the Kjeldahl method. Results indicate that leaves of vegetative broom have lower concentrations of Ca, Mg, S, Fe, Mn, and Ni than healthy leaves. Concentrations of P and Cu were lower in healthy leaves and higher in leaves of ...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research

Development of a Methodology Based on Extraction Induced by Emulsion Breaking for Copper Determination in Gasohol by Graphite Furnace Atomic Absorption Spectrometry
The development of a method based on extraction induced by emulsion breaking (EIEB) aiming copper determination in gasohol using graphite furnace atomic absorption spectrometry (GF AAS) is reported. Emulsification of the gasohol samples was carried out using nitric acid solution, (1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol surfactant (Triton X-114), and ultrasound energy. The variables related to the extraction efficiency were optimized by multivariate approaches (two-level factorial fractional design and Doehlert design). The best results were obtained when the emulsion was formed with 5.0 mL of the sample, 0.200...
Source: Journal of the Brazilian Chemical Society - February 2, 2021 Category: Chemistry Source Type: research