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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) co...
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 surface of the ban...
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 32.71 �...
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. (Source: Journ...
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 inhibitory ...
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 3,5-di-te...
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