Journal of the Brazilian Chemical Society This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Intercalation of Apocarotenoids from Annatto (Bixa orellana L.) into Layered Double Hydroxides
Synthetic conditions were evaluated to intercalate norbixin into layered double hydroxides (LDH). Norbixin was isolated from a hydrosoluble commercial annatto extract. LDH samples comprising M2+/Al3+ (M = Mg, Zn) were synthesized by coprecipitation and characterized by X-ray diffraction, thermal analysis coupled to mass spectrometry, vibrational spectroscopies, and solid-state 13C nuclear magnetic resonance. Radical scavenging activity of LDH hybrids was monitored by electron paramagnetic resonance towards the stable radical DPPH (1,1-diphenyl-2-picrylhydrazyl). LDH hosts presented more than 50 wt.% of norbixin and d-spaci...
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research

Hybrid Hydrogels Based on Polyethylene Glycol Bioconjugated with Silylated-Amyloidogenic Peptides
Hybrid-peptide hydrogel arrangements are a promising alternative to obtaining biocompatible structures at the nanoscopic scale. In this work, a new class of hybrid hydrogels was obtained through the sol-gel process based on the reaction between an amyloid-like octapeptide sequence [RF]4 (where R = arginine and F = phenylalanine) covalently bonded with glycine-linked alkoxysilanes, and hybrid silylated polyethylene glycol (PEG). 1H nuclear magnetic resonance (NMR), liquid chromatography-mass spectrometry (LC-MS), and Fourier transform infrared spectroscopy (FTIR) analyses were used, resulting in synthesized precursor/interm...
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research

Supramolecular Approach in Energy Conversion Devices
This review summarizes investigations carried out at the Laboratory of Photochemistry and Energy Conversion (LFCE) in the University of S ão Paulo dealing with design and characterization of ruthenium(II), rhenium(I) and iridium(III) polypyridine complexes with desired photochemical and photophysical properties in light of the development of optoelectronics and photoinduced energy conversion systems. First, the breakthroughs on molec ular engineering of emissive ReI, RuII and IrIII complexes for the development of highly efficient light-emitting devices, such as organic light-emitting diodes (OLEDs) and light-emitting ele...
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research

Living, Social, Small and Challenging
(Source: Journal of the Brazilian Chemical Society)
Source: Journal of the Brazilian Chemical Society - October 30, 2020 Category: Chemistry Source Type: research

Exploring Polypyrrole as Extraction Phase for Disposable Pipette Extraction Method for Multiclass Organic Micro-Pollutant Determination in River and Tap Water Using Gas Chromatography-Mass Spectrometry
The use of a polypyrrole (PPy) is described as an efficient extraction phase for disposable pipette extraction (DPX), in a fast and ruggedized analytical method for simultaneous determination of 18 organic micro-pollutants in water using gas chromatography-mass spectrometry (GC-MS). The DPX-blank pipettes were filled with PPy, a material produced through the chemical polymerization of PPy using iron(III) chloride hexahydrate. The optimized conditions were 5 extraction cycles with 600 µL of sample, adjusted to pH 9, and desorption with 150 µL of ethyl acetate using 7 cycles with the same aliquot. The calibration curves re...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Theoretical Calculations on the Mechanism of Hydrogenation of Diphenylacetylene over Pdn (n = 1-4) Clusters
Diphenylacetylene (DPA) is a precursor of stilbene and benzil, and reduction of DPA or its derivatives with metallic reagents is both an old and contemporary topic of research. By means of density function theory (DFT) calculations, a detailed investigation of the mechanism of the hydrogenation of DPA over Pd clusters was carried out at the molecular level. The various species structures in the hydrogenation of DPA over Pd clusters were optimized and analyzed. The calculations indicate that the reactions over different Pd clusters share similar reaction mechanisms, and the entire reaction path could be divided into approxi...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Determination of Bisphenol A in Paper Products by Synchronous Fluorescence Spectoscopy and Estimation of Daily Exposure
In this study, a simple and fast procedure was developed and validated for the determination of bisphenol A (BPA) in paper products using synchronous fluorescence spectroscopy. The method was used for the determination of BPA in thirteen types of paper products, including thermal receipt papers, lottery tickets, bus tickets, business cards, mailing envelopes, flyers, napkins, printing paper, food contact paper, kitchen rolls, toilet paper, newspapers, and magazines. BPA was found in 98% of thermal receipt papers (n = 341) at concentrations ranging from below the limit of quantification (LOQ) to 27.7 mg g − 1 with a geome...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Isolation, Absolute Configuration and Cytotoxic Activities of Alkaloids from Hippeastrum goianum (Ravenna) Meerow (Amaryllidaceae)
The phytochemical study of Hippeastrum goianum led to the identification of 13 compounds by means of gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). Compounds 7-demethoxy-9-O-methylhostasine (1) and 7-deoxi-trans-dihydronarciclasine (2) had their absolute configurations determined by vibrational circular dichroism (VCD). This is the first time that compound 1 is described in the Amaryllidaceae family. The cytotoxicity of all isolated compounds was tested against colorectal carcinoma (HCT 116), breast carcinoma (MCF-7), and non-tumor human retinal pigment epithelium (RPE) cell lines. The h...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

A Simple Approach to Analyze Sugar Nectar Composition in Flowers Using Capillary Electrophoresis and Enzymatic Assays
Despite the obvious importance of nectar, the composition of this solution remains surprisingly understudied to most of the flowers. Here we describe a simple, low-cost, and reliable methodology to analyze the three main sugars present in 210 nectar samples of Christmas Bellflowers using capillary electrophoresis (CE) and enzymatic assays. CE separation (-16 kV) was made using an electrolyte containing 36 mM NaOH pH 12, 15 mM sorbic acid, 0.5 mM hexadecyl trimethylammonium bromide (CTAB), and indirect UV detection. 72.9% of analyzed nectar samples were sucrose dominant; 13.3% sucrose rich only and 13.8% were fructose rich....
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Preparation of a New Polymeric Deep Eutectic Solvent and Its Application in Vortex-Assisted Liquid-Liquid Microextraction of Parabens in Foods, Cosmetics and Pharmaceutical Products
A vortex-assisted liquid-liquid microextraction method combined with high performance liquid chromatography-diode array detector has been developed for the determination of parabens in foods, cosmetics and pharmaceutical products. In this work, polymeric deep eutectic solvents composed of DL-menthol and polyethylene glycol with three different light grades were prepared successfully for the first time and used as extraction solvents. The influencing parameters on the extraction efficiency including type of extraction solvent, salt addition, composition of deep eutectic solvent, volume of extraction solvent, extraction time...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Virtual Screening of Secondary Metabolites of the Family Velloziaceae J. Agardh with Potential Antimicrobial Activity
The objective of this work was to carry out a bibliographic survey of secondary metabolites isolated from the Velloziaceae family, creating a bank of compounds. After the bank was created, four prediction models for potentially active compounds against pathogenic microorganisms (Candida albicans, Escherichia coli, Pseudomonas aeruginosa and Salmonella sp.) were obtained trying to identify which metabolites would be more active against the strains. Four sets of compounds with known activity for microorganisms were selected for the construction of predictive models from the CHEMBL database. Another bank with 163 unique molec...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

One-Step Isolation of Monoterpene Indole Alkaloids from Psychotria leiocarpa Leaves and Their Antiviral Activity on Dengue Virus Type-2
The leaf MeOH extract of Psychotria leiocarpa (Rubiaceae) showed in vitro non-cytotoxic and anti-dengue virus serotype 2 (DENV2) activity in human hepatocarcinoma cell lineage (HepG2). A one-step and cost-effective reversed-phase solid-phase extraction method based on high-performance liquid chromatography (HPLC) parameters allowed the isolation, directly from this bioactive extract, of the monoterpene indole alkaloids: N-glucopyranosyl vincosamide (1), vincosamide (2) and strictosidinic acid (3). The chemical structures were characterized based on 1D and 2D nuclear magnetic resonance (NMR), UV and high-resolution mass spe...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Synthesis, in silico Study, Theoretical Stereochemistry Elucidation and Antifungal Activity of New Imides Derived from Safrole
Ten imides derived from safrole, 4a-4j, were synthesized and their structures were fully characterized by infrared (IR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and high resolution mass spectrometry (HRMS) analysis. Among the ten imides studied, eight are new. The compounds were evaluated in an in silico study and showed strong to moderate antifungal activity against various strains of Candida and Cryptococcus. In particular, compounds 4b, 4c and 4h exhibited strong antifungal activity, with minimum inhibitory concentration (MICs) between 0.17-0.73 µmol mL-1. The compound 4j exhibited antifun...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Multivariate Analysis: Use of Doehlert Design (DD) for Optimization of a Simple Sample Preparation Procedure for the Determination of Inorganic Constituents in Cocoa Beans Employing Microwave Acid Digestion and ICP OES
This study presents a microwave-assisted procedure for sample preparation of cocoa beans using diluted HNO3 with H2O2 for the determination of Ba, Ca, Cu, K, Mg, Mn, P, S, Sr and Zn by inductively coupled plasma optical emission spectrometry (ICP OES). Doehlert modified design was used for optimization of experimental condition, and the volume of H2O2 (0, 0.5, 1.75 and 3 mL) and concentration of HNO3 (0.5, 3.75 and 7 mol L-1) were evaluated. The best experimental conditions were chosen considering lower residual acidity (RA), lower dissolved organic carbon (DOC) and the acceptable trueness range (80-120%), were 5 mL of 3.7...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research

Pueraria lobata Root Constituents as Xanthine Oxidase Inhibitors and Protective Agents against Oxidative Stress Induced in GES-1 Cells
Ultrafiltration coupled with liquid chromatography-mass spectrometry (LC-MS) was established to screen xanthine oxidase (XO) inhibitors from Pueraria lobata root extract. Four compounds were screened out and identified as puerarin, daidzin, daidzein and genistein with half-maximal inhibitory concentration (IC50) values of 30.8, 5.31, 14.5 and 3.02 µg mL − 1 on XO, respectively. The interactions between these compounds and XO were investigated by fluorescence spectroscopic method. The hydrogen peroxide induced oxidative stress model of human normal gastric epithelial cell lines (GES-1) was used to investigate the protect...
Source: Journal of the Brazilian Chemical Society - October 9, 2020 Category: Chemistry Source Type: research