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Journal of the Brazilian Chemical Society, Volume: 33, Número: 1, Publicado: 2022
  • Forging Ahead, Despite Uncertainties Editorial

    Vieira, Paulo Cezar
  • Synthesis and Biological Evaluation of Novel 1,3-Benzoxathiol-2-one Sulfonamides against Toxic Activities of the Venom of Bothrops jararaca and Bothrops jararacussu Snakes Article

    Chazin, Eliza L.; Martins, Leonardo B.; Souza, Marcus Vinícius N. de; Gomes, Claudia Regina B.; Silva, Ana Cláudia R. da; Branco, Marcelly C.; Sanchez, Eladio F.; Fuly, André L.; Vasconcelos, Thatyana R. A.

    Resumo em Inglês:

    This work describes the synthesis of new 1,3-benzoxathiol-2-one sulfonamides and evaluation of their ability to inhibit some in vitro (coagulant, proteolytic and hemolytic) and in vivo (hemorrhagic, edematogenic and lethality) toxic activities of Bothrops jararaca and Bothrops jararacussu venoms. Compounds have been synthesized from the coupling of intermediate 5-amino-6 methoxybenzo[d][1,3]oxathiol-2-one 4 with benzenesulfonyl chlorides. Characterization of the products was achieved by nuclear magnetic resonance (NMR) and electrospray ionization mass spectra (ESI-MS) techniques. Biological assay results have shown that most of compounds inhibited the main toxic activities of the venom of the two snake species. Compound 5b (N-(6 methoxy-2 oxobenzo[d][1,3]oxathiol-5-yl)-4-nitrobenzenesulfonamide) was the most efficient in inhibiting hemolysis of B. jararaca, and coagulation and proteolysis induced by both venoms. For in vivo activities, all compounds inhibited the edema, from 35 to 72%, and most of them exhibited antihemorrhagic and antilethality activities. Thus, the results pointed to the biological potential of these compounds, being promising molecules to treat envenomation by these snakes as well as to aid the current antivenom serum therapy.
  • Heteroannulation Reaction of α-Aminoketones for the Efficient Synthesis of 4-Imidazolin-2-ones and 2-Thiones Article

    Rebollar, Araceli; Bautista, Rafael; Gutiérrez, Rsuini U.; Espinoza-Hicks, Carlos; Mendieta, Aarón; Zárate-Zárate, Daniel; Martínez-Mora, Eder I.; Labarrios-Morán, Ehecatl M.; Vázquez, Miguel A.; Delgado, Francisco; Tamariz, Joaquín

    Resumo em Inglês:

    The hydrogenation of α-oximinoketones in methanol/HCl afforded α-aminoketones, which were applied without purification to the synthesis of 4-imidazolin-2-ones and 2-thiones, including chiral derivatives. The latter two series were obtained in high yields by a heteroannulation reaction of α-aminoketones with isocyanates and isothiocyanates, respectively. A double condensation of the α-aminoketones with two mol equivalents of the isocyanates produced a series of 4,5-dialkyl-N,3-diaryl-2-oxo-2,3-dihydro-1H-imidazole-1-carboxamides. With isothiocyanates, a single condensation reaction furnished a series of 4,5-dialkyl-1-aryl-1H-imidazole-2(3H)-thiones, which underwent alkylation with alkyl halides to form the corresponding 1-aryl-2-thioalkyl-1H imidazoles in high yields.
  • Light-Assisted Batch Injection Analysis of Glucose Exploiting a p-n-Homojunction Based on Cu2O Article

    Cardoso, Elenilse R.; Menezes, Alan S. de; Santos, Clenilton C. dos; Luz, Rita de Cássia S.; Damos, Flávio S.

    Resumo em Inglês:

    This work describes the development of a photoelectrochemical sensor for glucose quantification exploiting a light assisted-batch injection analysis (BIA) cell. A light-emitting diode (LED) lamp was employed to control the incidence of light on the p-Cu2O/n-Cu2O/fluorine-doped tin oxide (FTO) photoactive platform in BIA cell. The p-Cu2O/n-Cu2O/FTO platform was constructed by electrodepositing n-Cu2O and p-Cu2O and the characteristics of electrodeposited Cu2O films were investigated by X-ray diffraction (XRD), Raman spectroscopy, and electrochemical impedance spectroscopy. The light assisted-batch injection analysis of glucose based on the illuminated p-Cu2O/n-Cu2O/FTO photoelectrode presented a linear response of 10 μmol L-1-1 mmol L-1, a limit of detection of 4.0 μmol L-1, and sensitivity of 0.768 ± 0.011 μA L μmol-1 cm-2. The system presented an average recovery value of 96% when applied to the determination of glucose in an artificial saliva sample, which indicates that the incidence of light on photoelectroactive platforms is a promising approach for the determination and quantification of glucose.
  • Dispersive Solid-Phase Extraction Using 3-Mercaptopropyltrimethoxysilane Functionalized Magnetic MWCNT-Based Nanocomposite for Selective and Efficient Preconcentration of Pb2+ with FAAS Determination Article

    Santos, Paula M. dos; Tarley, César R. T.; Corazza, Marcela Z.

    Resumo em Inglês:

    A novel nanocomposite based on magnetic multiwalled carbon nanotubes coated with SiO2 and functionalized with 3-mercaptopropyltrimethoxysilane (3-MPTMS) was prepared for the efficient extraction and quantification of lead ions from water samples. The adsorption capacity of this adsorbent could reach 1.995 mg g-1 Pb2+ in an equilibrium time of 30 min. Under optimized conditions derived using the 25-1 fractional factorial design, a 45 mL aliquot of the sample was preconcentrated onto 90 mg of nanocomposite during 4 min. The lead ions adsorbed on the nanocomposite were eluted using 2 mol L-1 HNO3. The proposed method provided a preconcentration factor of 15.25 times, yielding limits of detection (LOD) and quantification (LOQ) of 0.56 and 1.86 µg L-1, respectively, and a linear range between 1.86 and 100.00 µg L-1. The relative standard deviations (RSD, n = 10), determined using solutions of Pb2+ at 10 and 120 µg L-1, were 2.3 and 2.1%, respectively. A high tolerance toward potentially foreign ions was observed. The proposed method was successfully applied to the rapid extraction of Pb2+ ions from different water samples, confirming good recovery values (90.33-109.53%); the accuracy of the method was evaluated through graphite furnace atomic absorption spectrometry (GF AAS) as a reference technique.
  • Diacetate Naphthoquinone Derivatives Tethered to 1,2,3-Triazoles: Synthesis and Cytotoxicity Evaluation in Caco-2 Cells Article

    Costa, Dora C. S.; Francisco, Adriane S.; Matuck, Beatriz V. A.; Furtado, Priscila S.; Oliveira, Alana A. S. C. de; Rabelo, Vitor W.-H.; Sathler, Plínio C.; Abreu, Paula A.; Ferreira, Vitor F.; Silva, Luiz Cláudio R. P. da; Silva, Fernando C. da

    Resumo em Inglês:

    Acetylated compounds prepared from naphthoquinones have been reported as antitumoral prodrugs. Exploring the synthetic versatility of the naphthoquinone and triazolic nuclei, herein we report a simple and efficient synthetic route to prepare a series of sixteen prodrugs prototype of 1,2,3-triazoles-naphthoquinodoic acetyl derivatives. The compounds 10a-10h and 11a-11h were obtained by oxidative cycloaddition reaction between lawsone and 4-vinyl-1H-1,2,3-triazoles promoted by ceric ammonium nitrate (CAN) in alkaline medium followed by reductive acetylation of the quinones in excess of metallic zinc and acetic anhydride in yields up to > 98%. All derivatives revealed to be hemocompatible and the compound 11e exhibited the most promising profile against Caco-2 cells showing the higher selectivity index. Molecular docking suggests that these compounds could exert their cytotoxic activity through inhibition of one topoisomerase II isoform, at least.
  • Household Infrared Technology as an Energy-Efficient Approach to Achieve C-Cπ Bond Construction Reactions Article

    Ríos-Guerra, Hulme; Penieres-Carrillo, Guillermo; Barrera-Téllez, Francisco; Martínez-Záldivar, Alejandro; Pérez-Flores, Javier; Hipólito-Nájera, Adrian Ricardo; Luna-Mora, Ricardo Alfredo

    Resumo em Inglês:

    We examined the ability of short-wave infrared (IR) light in the λ1.5-3.0 μm region of the infrared emission spectrum to accomplish C-Cπ bond construction reaction between π-excessive azaheteroaromatic and different carbonyl substrates supported on a bentonitic clay catalyst in solventless condition via a three-component condensation reaction. Preliminary studies show that the implementation of a domestic Flavor-Wave® oven fitted with a halogen heater lamp as a chemical reactor was as effective as the use of near IR light (λ1.1 μm) in fostering batch-wise organic reactions. Overall, this approach reveals its potential exploitation as an energy-efficient source to assemble biologically engaging (hetero)arenebisindolylmethanes framework, in the same way, that assure its sustainable development as for efficient generation of small libraries of molecules comparable to high-tech instrumentations performances.
  • New Attempts to Synthesize Layered Double Hydroxides Intercalated with SO42-/Cs+ Using Co-Precipitation and Exchange Reactions Article

    Sotiles, Anne R.; Wypych, Fernando

    Resumo em Inglês:

    Layered double hydroxides (LDHs) with the compositions (Cs+/NH4+)0.111[M2+0.667Al0.333(OH)2.0 (SO4)0.222] (M2+ = Mn, Zn) and basal distance of ca. 11 Å were obtained by co-precipitating Mn/Al and Zn/Al sulfate salts with aqueous NH3, using excess of Cs2SO4. [Mn0.667Al3+0.333(OH)2]Cl0.333.nH2O and [M2+0.667Al3+0.333(OH)2](NO3)0.333.nH2O (M2+ = Mn, Zn) were also synthesized by co-precipitation, presenting respective basal distances of 8.92 and 7.92 Å. After applying exchange reactions with excess of Cs2SO4, materials with basal distances of ca. 11 Å were obtained, indicating the exchange of chloride and nitrate with sulfate, without incorporation of Cs+. When Na+0.111[M2+0.667Al0.333(OH)2.0(SO4)0.222](M2+ = Mn, Zn) obtained by co-precipitation and having basal distances of ca. 11 Å was exchanged with excess of Cs2SO4, the content of sulfate remained constant and Na+ was partially replaced with Cs+, but the amount was lower, indicating the probable composition (Na+/Cs+)y[M2+0.667Al0.333(OH)2-y(SO4)y/2(SO4)0.222-(y/2)](M2+ = Mn, Zn), where some of the hydroxide anions were replaced with grafted SO42-.
  • Quality Control for Lignin and Gelatin Microcapsules Loaded with Orange Essential Oil Article

    Aguiar, Maria Clara S.; Denadae, Bárbara E.; Silva, Maria Fátima G. F.; Fernandes, João B.; Bittencourt, Paulo R. S.; Scremin, Fernando R.; Forim, Moacir R.

    Resumo em Inglês:

    Sustainable natural product-based microstructured systems and biopolymers are strong candidates for use in crop protection. Lignin and gelatin microcapsules loaded with orange essential oil were developed with spray-drying in order to enhance its potential. We evaluated the microparticle controlled release mechanisms, biological effects, structural and thermal properties. A quantitative method using headspace-gas chromatography was developed and evaluated for the controlled release of the essential oils. Controlled release studies showed a linear relationship between the biopolymer and essential oil concentrations when retaining volatile compounds. Thermal analyses demonstrated increases in essential oil stability when microencapsulated, especially for lignin as a biopolymer. These results showed that biopolymer type was the main factor influencing quality analysis parameters. Finally, microcapsules loaded with orange essential oil were applied in a bioassay, and showed gains in toxicity against Spodoptera frugiperda compared to non-encapsulated oil.
  • Volatile Constituents of Floral Scents from Encyclia cordigera (Kunth) Dressler and E. randii (Barb. Rodr.) Porto & Brade (Orchidaceae) Article

    Vasconcelos, Franciléia M. de; Andrade, Eloisa Helena A.; Teixeira, Luiz Otávio A.; Maia, José Guilherme S.

    Resumo em Inglês:

    Encyclia cordigera is native from Central America tropical region, and Encyclia randii occurs at Brazilian Amazon environment domains. Floral concentrates from both Encyclia species were extracted, analyzed by gas chromatography-mass spectrometry, and identified compounds belong to terpenoids, phenylpropanoids, and fatty acid derivatives classes. Primary constituents of the E. cordigera floral scent were β-ionol (45.4%), terpinen-4-ol (12.4%), benzyl benzoate (5.6%), and indole (5.0%). (2E,6Z)-Farnesol (24.9%), heptanal (11.8%), (E)-nerolidol (9.4%), nonanal (6.4%), p-vinyl-guaiacol (6.0%), and phenylethyl benzoate (5.3%) have predominated in the floral scent of E. randii. From the olfactory standpoint, E. cordigera scent was previously characterized as a blend of ionone-floral and aromatic-floral notes. Very likely, E. randii scent presents the woody fragrance due to sesquiterpenes (2E,6Z)-farnesol and (E)-nerolidol and the fruity note from the aldehydes heptanal and nonanal. Floral perfume plays a fundamental role in attracting pollinating insects, whose symbiosis contributes to the appearance of chemical variations in orchid species.
  • Mathematical Modeling of the Film Influence on the Salting Time of Mozzarella Cheese in a Static and Dynamic System: Application of Artificial Neural Networks of the Multilayer Perceptron Type Article

    Borsato, Dionisio; Souza, Winnicius M. de; Oliveira, Talita F. de; Clemente, Marco A. J.; Silva, Hágata C.; Mantovani, Ana C. G.; Chendynski, Letícia T.; Angilelli, Karina B.

    Resumo em Inglês:

    The NaCl and KCl diffusion in the film formed on the cheese surface during salting was simulated by the finite element method. The time and salts concentration values on the cheese surface were determined, tabulated, and presented to the multilayer perceptron neural network (MLP) for the regression modeling. The samples were divided into 70, 15 and 15% for training, testing, and validation, respectively. The networks with the best performance showed 5 to 12 hidden layers. The Tukey’s test showed that there was no significant difference, at the 5% level, between the time value used and the mean value modeled for training, testing, and validation for the NaCl. For the KCl, a significant difference was observed only for 2 training samples and 1 test sample. Sensitivity analysis showed that the discrete variable Z, which represents the static and dynamic systems, was the most important in the models’ construction.
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