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We herein evaluate a biological applicability of 1,3-substituted cuneanes as an isostere of m-substituted benzenes based on its structural similarity. An investigation of a method to obtain 1,3-substituted cuneanes by selective isomerization of 1,4-substituted cubanes enables this attempt by giving a key synthetic step to obtain a cuneane analogs of pharmaceuticals having m-substituted benzene moiety. Biological evaluation of the synthesized analogs and in silico study of the obtained result revealed a potential usage of cuneane skeleton in medicinal chemistry.
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Derivados de Benzeno , Benzeno , Benzeno/química , Isomerismo , Derivados de Benzeno/químicaRESUMO
Fucoxanthin, a brown algae carotenoid, has attracted great interest because of its numerous biological activities supported by in vitro and in vivo studies. However, its chemical structure is susceptible to alterations when subjected to food processing and storage conditions, such as heat, oxygen, light, and pH changes. Consequently, these conditions lead to the formation of fucoxanthin derivatives, including cis-isomers, apo-fucoxanthinone, apo-fucoxanthinal, fucoxanthinol, epoxides, and hydroxy compounds, collectively known as degradation products. Currently, little information is available regarding the stability and functionality of these fucoxanthin derivatives resulting from food processing and storage. Therefore, enhancing the understanding of the biological effect of fucoxanthin derivatives is crucial for optimizing the utilization of fucoxanthin in various applications and ensuring its efficacy in potential health benefits. To this aim, this review describes the main chemical reactions affecting the stability of fucoxanthin during food processing and storage, facilitating the identification of the major fucoxanthin derivatives. Moreover, recent advancements in the structure-activity relationship of fucoxanthin derivatives will be critically assessed, emphasizing their biological activity. Overall, this review provides a critical updated understanding of the effects of technological processes on fucoxanthin stability and activity that can be helpful for stakeholders when designing processes for food products containing fucoxanthin.
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The light-induced processes performed by photofunctional polymer films are crucial aspects of developing integrated energy storage devices properly. Herein, we report the preparation, characterization, and study of the optical properties of a series of biobased cellulose acetate/azobenzene (CA/Az1) handleable films at different compositions. The photoswitching/back-switching behavior of the samples was investigated using varied LED irradiation sources. Additionally, poly(ethylene glycol) (PEG) was deposited onto cellulose acetate/azobenzene films to study the back-switching process's effect and nature in the fabricated films. Interestingly, the melting enthalpies of PEG before and after being irradiated with blue LED light were 2.5 mJ and 0.8 mJ, respectively. Conveniently, FTIR and UV-visible spectroscopy, thermogravimetry (TGA), contact angle, differential scanning calorimetry (DSC), polarized light microscopy (PLM), and atomic force microscopy (AFM) were used for the characterization of the sample films. Complementarily, theoretical electronic calculations provided a consistent approach to the energetic change in the dihedral angles and non-covalent interaction for the trans and cis isomer in the presence of cellulose acetate monomer. The results of this study revealed that CA/Az1 films are viable photoactive materials displaying handleability attributes with potential uses in harvesting, converting, and storing light energy.
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Luz , Raios Ultravioleta , Celulose/químicaRESUMO
The reaction between L-cysteine (Cys) and 6-maleimidohexanoic acid (Mhx) in an aqueous medium at different levels of pH was analyzed via RP-HPLC, finding the presence of two reaction products throughout the evaluated pH range. By means of solid-phase extraction (SPE), it was possible to separate the products and obtain isolated profiles enriched up to 80%. The products were analyzed individually through mass spectrometry, DAD-HPLC, NMR 1H, 13C, and two-dimensional evidence of isomerization between the hydrogen atoms of the α-amino and the thiol group present in the cysteine. Thus, it was concluded that the products obtained corresponded to a mixture of the isomer Cys-S-Mhx, where the adduct is formed by a thioether bond, and the isomer Cys-NH-Mhx, in which the union is driven by the amino group. We consider that the phenomenon of isomerization is an important finding, since it has not previously been reported for this reaction.
Assuntos
Cisteína , Compostos de Sulfidrila , Cromatografia Líquida de Alta Pressão , Cisteína/química , Isomerismo , Maleimidas/química , Compostos de Sulfidrila/químicaRESUMO
Triosephosphate isomerase (TIM) is a key enzyme in glycolysis that catalyses the interconversion of glyceraldehyde 3-phosphate and dihydroxy-acetone phosphate. This simple reaction involves the shuttling of protons mediated by protolysable side chains. The catalytic power of TIM is thought to stem from its ability to facilitate the deprotonation of a carbon next to a carbonyl group to generate an enediolate intermediate. The enediolate intermediate is believed to be mimicked by the inhibitor 2-phosphoglycolate (PGA) and the subsequent enediol intermediate by phosphoglycolohydroxamate (PGH). Here, neutron structures of Leishmania mexicana TIM have been determined with both inhibitors, and joint neutron/X-ray refinement followed by quantum refinement has been performed. The structures show that in the PGA complex the postulated general base Glu167 is protonated, while in the PGH complex it remains deprotonated. The deuteron is clearly localized on Glu167 in the PGA-TIM structure, suggesting an asymmetric hydrogen bond instead of a low-barrier hydrogen bond. The full picture of the active-site protonation states allowed an investigation of the reaction mechanism using density-functional theory calculations.
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This study focuses on examining the isomerization of allyl alcohol using ruthenium (Ru) supported on alumina as a heterogeneous catalyst. The synthesized Ru/Al solids were characterized by various characterization techniques. The content of Ru was estimated by the energy dispersive x-ray technique. The x-ray diffraction (XRD) confirmed the presence of phases in the support and active species in the catalysts. The surface area of the support after Ru impregnation and the pore volume were determined by nitrogen physisorption. The analysis of programmed temperature (TPR and TPO) shows different redox sites which is confirmed by XPS. The catalytic results suggest a dependence on the amount of available metallic Ru, as well as the importance of the continuous regeneration of the metal using H2 to achieve a good conversion of the allyl alcohol. For comparison purposes, the commercial Ru on alumina 5% (CAS 908142) was used. The results show up to 68% alcohol conversion and 27% yield of the isomerization product using Ru(1,5.4h)/Al catalyst in comparison with 86% conversion and 39% yield of the isomerization product using CAS 908142. In contrast, our catalysts always presented higher TOF values (149-160) in comparison with CAS 908142 (101).
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Postharvest wounding stress in carrots induces the accumulation of phenolics, whereas extrusion generates modifications in the nutritional profiles of food matrixes. In the present study, the sequential application of wounding stress and extrusion on total free and bound phenolics as well as on carotenoid profiles of carrots was evaluated. Wounding was applied by shredding carrots and storing the tissue (48â¯h, 15⯰C). The stressed-tissue was dehydrated and extruded at 63⯰C or 109⯰C and at continuous or expansion screw configurations. Extrudates were milled and sieved before phytochemical analysis. Wounding increased total free (288.1%) and bound (407.6%) phenolic content, whereas the carotenoid content was unaltered. The free and bound phenolics that showed the highest increase due to wounding were the chlorogenic (579.8%) and p-coumaric (390.9%) acids. Extrusion, at 109⯰C under expansion screw configuration, further increased the wound-induced accumulation of total free (296.6%) and bound (22.1%) phenolics and induced trans-cis isomerization of ß-carotene.
Assuntos
Daucus carota/química , Fenóis/análise , Carotenoides/análise , Compostos Fitoquímicos/análise , Estresse FisiológicoRESUMO
Regarding free genistein small delivery to the central nervous system, physico-chemical parameters of dimiristoylphosphatidylcholine liposome-loaded genistein were investigated, as well as its in vitro activity against the DPPH radical and glioma cells. Data obtained by UV-vis spectroscopy, Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance, Differential Scanning Calorimetry and Dynamic Light Scattering were used to characterize the liposomal system with respect to motion restriction, hydration degree, trans-gauche isomerization and phase state. In vitro antitumoral effects were monitored through conting and viability assays. Genistein hydroxyl group and lipid hydrogen bonds may have important role in dimiristoylphosphatidylcholine phosphate and choline motion restriction. Genistein-induced choline restriction may be also related to a decrease in the group rotation rate. Genistein: dimiristoylphosphatidylcholine system showed higher molecular package at the acyl chains region compaired to empty liposomes, and it may be related to a decrease in gauche bonds quantity and system size. Lipid acyl chain length seems to influence different genistein effects on membranes, due to the presence of gauche conformers. Genistein: dimiristoylphosphatidylcholine liposome was more efficient as DPPH reducting system than the free-Gen. Liposomal system, at genistein 100 µM, was so efficient as the correspondent free-form genistein, probably showing higher stability to cross the blood-brain barrier. Genistein and the lipid did not show an additive activity against glioma cells. Antioxidant and anti-glioma genistein-loaded liposome potential may be related to the isoflavone location and its restriction effect in the lipid molecular motion. Anti-glioma activity may also be related to a decrease of system size and trans-gauche isomerization.
Assuntos
Antineoplásicos/farmacologia , Antioxidantes/farmacologia , Sistemas de Liberação de Medicamentos , Genisteína/farmacologia , Glioma/tratamento farmacológico , Fosfatidilcolinas/farmacologia , Animais , Antineoplásicos/química , Antioxidantes/química , Compostos de Bifenilo/antagonistas & inibidores , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Genisteína/química , Glioma/metabolismo , Glioma/patologia , Estrutura Molecular , Fosfatidilcolinas/química , Picratos/antagonistas & inibidores , Ratos , Relação Estrutura-Atividade , Células Tumorais CultivadasRESUMO
Penta(ammine)ruthenium benzotriazole complexes [RuII/III (NH3 )5 bta]+/2+ and [RuII/III (NH3 )5 btaH]2+/3+ (bta and btaH are the deprotonated and neutral form of the triazole ligand, respectively) can exhibit two linkage isomers κN1 and κN2. This system was investigated by density functional theory natural bond orbitals analysis and Su-Li energy decomposition analysis. Steric, electrostatic, exchange, repulsion, polarization, and dispersion energy components of the total metal-ligand interaction were quantitatively evaluated, and revealed that the overall metal-triazole ligand is comprised of donor-acceptor interactions like σ-donation and π-back-donation, which favors a specific isomer depending on the oxidation state of the ruthenium and the charge of the ligand. Further, activation energies (ΔG ) for linkage isomerization reactions were calculated. Results were correlated with experimental chemical-electrochemical data and two plausible mechanisms are discussed. © 2019 Wiley Periodicals, Inc.
RESUMO
The scope and limitations of Eaton's rhodium(I)-catalyzed valence isomerization of cubane to cyclooctatetraene (COT) were investigated in the context of functional group tolerability, multiple substitution modes and the ability of cubane-alcohols to undergo one-pot tandem Ley-Griffith Wittig reactions in the absence of a transition metal catalyst.
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Resumen Se sintetizó el catalizador Cu/MCM-41 mediante impregnación húmeda incipiente y se caracterizó por DRX, XPS, TPD-NH3 y adsorción-desorción de N2. Se evaluó el efecto de diferentes condiciones de reacción (temperatura, tiempo, tipo de solvente y cantidad de catalizador) en la isomerización del epóxido de α-pineno para la obtención de aldehído canfolénico con el catalizador Cu/MCM-41, que no había sido reportado previamente para este tipo de reacción. Se partió de un diseño experimental central compuesto mediante análisis de superficie de respuesta. Se encontró que la mejor selectividad fue de 85% (5 mg de catalizador; 70 °C; 0,5 h y el uso de acetato de etilo como solvente). Adicionalmente, se determinaron los principales factores y sus combinaciones que tenían mayor significancia en la síntesis del aldehído ajustado a un modelo polinomial de segundo grado. Se encontró que los factores que tienen mayor influencia en la conversión son la cantidad de catalizador, tiempo de reacción, el tipo de solvente y el factor combinado entre la cantidad de catalizador y el tipo de solvente. En el caso de la selectividad hacia el producto deseado no se encontró ningún factor significativo.
Abstract The Cu/MCM-41 catalyst was synthesized by incipient wet impregnation and characterized by XRD, XPS, TPD-NH3, and N2 adsorption-desorption. The effect of different reaction conditions (temperature, time, type of solvent, and amount of catalyst) on the isomerization reaction of α-pinene epoxide was evaluated to obtain camphoric aldehyde with the Cu/MCM-41 catalyst, which had not been previously reported for this kind of reaction. The experiment was based on a central composite experimental design composed by response surface analysis. The best campholenic aldehyde selectivity was found to be 85% (5 mg of catalyst, 70 °C, 0.5 h and the use of ethyl acetate as a solvent). Furthermore, the main factors and their combinations that had the greatest significance in the synthesis were adjusted to a polynomial second order model. The factors with the main influence on conversion were the catalyst amount, reaction time, solvent type, and the combined factor between catalyst amount and the solvent type. In the case of campholenic aldehyde selectivity no significant factor was found.
Resumo O catalisador Cu/MCM-41, sintetizado pelo método de impregnação a umidade incipiente, foi caracterizado por DRX, XPS, TPD-NH3 e adsorção-dessorção de N2 e testado na reação de isomerização do epóxido de α-pineno. Diferentes condições de reação foram exploradas a partir de um desenho experimental central composto. A melhor seletividade de aldeído camfolênico encontrada foi de 85% (5 mg de catalisador; 70 °C; 0,5 h e acetato de etilo como solvente). Além disso, os principais fatores e as combinações entre eles que tiveram influência na síntese do aldeído camfolênico foram ajustados a um modelo polinomial de segunda ordem. Verificou-se que os fatores com a principal influência na conversão foram a quantidade de catalisador, o tempo de reação e o tipo de solvente e o fator combinado entre a quantidade de catalisador e o tipo de solvente. No caso da seletividade do aldeído camfolênico, não foi encontrado um fator significativo.
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Abstract Whey (milk serum) is produced by the dairy industry during the manufacture of cheese. In addition to being a valuable source of functional and nutritional proteins, whey also presents almost all the lactose from the original whole milk. However, many industries still consider the whey as an effluent, which can cause serious environmental problems when not properly treated. Therefore, it is important to develop alternatives for the adequate use of whey. The lactose obtained from whey permeate can be converted into lactulose, a prebiotic which may be metabolized in the intestine by probiotic bacteria, such as Lactobacillus sp. and Bifidobacterium sp., through enzymatic isomerization or by using alkaline catalysts, with minimal secondary reactions and high yield. This manuscript provides information about various techniques used to produce lactulose, its purification and analysis, as well as its mechanisms of action and alternative applications in food products and medicines.
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The base-catalyzed isomerization of N-propargylamides or carbamates may furnish N-allenyl compounds (allenamides/allencarbamates) or further evolve to N-alkynyl compounds (ynamides or yncarbamates). The particular fate of this reaction varies from experiment to experiment and there is no clear rule for predicting the reaction outcome for a particular structure. With the support of ab initio and DFT computations, this work shows that observed results can be explained by assuming an exchange equilibrium between energetically close N-propargyl, allenyl and N-alkynyl forms and that the reaction outcome correlates to a particular equilibrium mixture. Due to the very small energy gap between the N-allenyl and N-alkynyl forms, small structural changes may easily alter the equilibrium position, explaining the variety of observed experimental results. Based on CBS-QB3 computations, the ωB97 functional provided reasonably accurate isomerization energies and could successfully predict the experimentally observed behavior for several examples from the literature.
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Hydrazones exhibit a versatile chemistry and are of interest for their potential use as functional molecular systems capable of undergoing reversible changes of configuration, i.e. E/Z isomerization. The title compound, C12H12N4O, has an E configuration with respect to the hydrazone C=N bond. The crystal packing is formed by N-H...N and O-H...N hydrogen bonds that give a two-dimensional layer structure and C-H...C interactions associated with layer stacking to produce the three-dimensional supramolecular structure. These intermolecular interactions were analyzed and quantified by the Hirshfeld surface method and the two-dimensional supramolecular arrangement was topologically simplified as a hcb network.
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Protein disulfide isomerase is an essential redox chaperone from the endoplasmic reticulum (ER) and is responsible for correct disulfide bond formation in nascent proteins. PDI is also found in other cellular locations in the cell, particularly the cell surface. Overall, PDI contributes to ER and global cell redox homeostasis and signaling. The knowledge about PDI structure and function progressed substantially based on in vitro studies using recombinant PDI and chimeric proteins. In these experimental scenarios, PDI reductase and chaperone activities are readily approachable. In contrast, assays to measure PDI isomerase activity, the hallmark of PDI family, are more complex. Assessment of PDI roles in cells and tissues mainly relies on gain- or loss-of-function studies. However, there is limited information regarding correlation of experimental readouts with the distinct types of PDI activities. In this mini-review, we evaluate the main methods described for measuring the different kinds of PDI activity: thiol reductase, thiol oxidase, thiol isomerase and chaperone. We emphasize the need to use appropriate controls and the role of critical interferents (e.g., detergent, presence of reducing agents). We also discuss the translation of results from in vitro studies with purified recombinant PDI to cellular and tissue samples, with critical comments on the interpretation of results.
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Herein we report the synthesis of the 6-(hydroxymethyl)pyridine-2-carboxaldehyde[2-methyl-pyrimidine-4,6-diyl]bis-hydrazone by a condensation reaction between 6-(hydroxymethyl)picolinaldehyde with 4,6-(bis-hydrazino)-2-methylpyrimidine. This bis-hydrazone can be visualized as a two-arm system which exhibits photochemical induced [E,E]/[E,Z]/[Z,Z’] isomerizations and double coordination to metal centers. Configurational changes, upon UV light irradiation, were followed over time by ¹H NMR, establishing that isomerization, in both arms, is a consecutive reaction that follows first-order kinetics (k1= 4.06 x 10-4 s-1 and k2= 2.80 x 10-4 s-1). Furthermore, the synthesis of bis-hydrazone metal complexes with La and Sm (III) ions was achieved; subsequently, the absorption and emission properties of these complexes were studied, determining the fluorescence quantum yields, ΦLa= 0.2024 and ΦSm= 0.1413. Electrochemical studies of the complexes were conducted by square wave voltammetry, demonstrating that the bis-hydrazone and its complexes are electroactive species between +1.5 and -2.5 V.
Se reporta la síntesis de la 6-(hidroximetil)piridin-2-carboxaldehído[2-metilpirimidina-4,6-diil]bishidrazona mediante la reacción de condensación entre el 6-(hidroximetil)piconaldehído con la 4,6-(bishidracino)-2-metilpirimidina. Esta bishidrazona puede ser visualizada como un sistema de dos brazos los cuales exhiben isomerizaciones [E,E]/[E,Z]/[Z,Z’] fotoquímicamente inducidas y coordinación a centros metálicos. Los cambios configuracionales, después de irradiación UV, fueron seguidos en el tiempo mediante RMN ¹H estableciendo que la isomerización, en ambos brazos del sistema, corresponde a una reacción consecutiva que sigue una cinética de primer orden (k1= 4,06 x 10-4 s-1 and k2= 2,80 x 10-4 s-1). Además se prepararon complejos metálicos de La y Sm(III), seguidamente, las propiedades de absorción y emisión de dichos complejos fueron estudiadas calculando rendimientos cuánticos de fluorescencia de ΦLa= 0,2024 y ΦSm= 0,1413. Estudios electroquímicos de los complejos se llevaron a cabo a través de voltametría de onda cuadrada indicando que los compuestos preparados poseen potenciales redox dentro del rango de trabajo del solvente.
Reporta-se a síntese da 6-(hidroximetil)piridin-2-carboxaldeído[2-metilpirimidina-4,6-diil]bis-hidrazona mediante a reação de condensação entre o 6-(hidroximetil)piconaldeído e a 4,6-(bis-hidrazino)-2-metilpirimidina. Esta bis-hidrazona pode ser visualizada como um sistema de dois braços os quais exibem isomerizações [E,E]/[E,Z]/[Z,Z’] fotoquimicamente induzidas e coordenação com íons metálicos (dupla coordenação a íons metálicos). Após a irradiação UV, as mudanças configuracionais foram monitoradas com o tempo por RMN 1H. Essas medidas estabeleceram que a isomerização em ambos braços do sistema corresponde a uma reação consecutiva apresentando uma cinética de primeira ordem (k1= 4.06 x 10-4 s-1 e k2= 2.80 x 10-4 s-1). Além disso, os complexos metálicos de La e Sm(III) foram preparados e suas propriedades de absorção e de emissão foram estudadas, calculando os rendimentos quânticos de fluorescência de ΦLa= 0.2024 e de ΦSm= 0.1413. Estudos eletroquímicos dos complexos foram feitos através de voltametria de onda quadrada indicando que os compostos preparados possuem potenciais redox dentro da faixa de trabalho do solvente.
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Conformational rearrangements in antibody·antigen recognition are essential events where kinetic discrimination of isomers expands the universe of combinations. We investigated the interaction mechanism of a monoclonal antibody, M1, raised against E7 from human papillomavirus, a prototypic viral oncoprotein and a model intrinsically disordered protein. The mapped 12-amino acid immunodominant epitope lies within a "hinge" region between the N-terminal intrinsically disordered and the C-terminal globular domains. Kinetic experiments show that despite being within an intrinsically disordered region, the hinge E7 epitope has at least two populations separated by a high energy barrier. Nuclear magnetic resonance traced the origin of this barrier to a very slow (t(1/2)â¼4 min) trans-cis prolyl isomerization event involving changes in secondary structure. The less populated (10%) cis isomer is the binding-competent species, thus requiring the 90% of molecules in the trans configuration to isomerize before binding. The association rate for the cis isomer approaches 6 × 10(7) M(-1) s(-1), a ceiling for antigen-antibody interactions. Mutagenesis experiments showed that Pro-41 in E7Ep was required for both binding and isomerization. After a slow postbinding unimolecular rearrangement, a consolidated complex with K(D) = 1.2 × 10(-7) M is reached. Our results suggest that presentation of this viral epitope by the antigen-presenting cells would have to be "locked" in the cis conformation, in opposition to the most populated trans isomer, in order to select the specific antibody clone that goes through affinity and kinetic maturation.
Assuntos
Anticorpos Monoclonais Murinos/química , Anticorpos Antivirais/química , Especificidade de Anticorpos , Papillomavirus Humano 16/química , Proteínas E7 de Papillomavirus/química , Animais , Anticorpos Monoclonais Murinos/imunologia , Anticorpos Antivirais/imunologia , Epitopos , Papillomavirus Humano 16/genética , Papillomavirus Humano 16/imunologia , Humanos , Camundongos , Ressonância Magnética Nuclear Biomolecular , Proteínas E7 de Papillomavirus/genética , Proteínas E7 de Papillomavirus/imunologia , Estrutura Secundária de ProteínaRESUMO
O óleo essencial de pimenta longa (Piper hispidinervum C. DC) é rico em safrol, tornando-o suscetível à reação de isomerização para a obtenção de cis, trans-isosafrol. O presente artigo apresenta a etapa de eletroxidação dos isômeros cis, trans-isosafrol advindos da isomerização direta do óleo essencial de pimenta longa, apresentando 99,7 por cento de conversão em isosafrol glicol, o qual é sujeito à oxidação com conversão de 99 por cento em piperonal, este apresentando 84,9 por cento de pureza.
The essential oil of long-pepper (Piper hispidinervum C. DC) is rich in safrole, then susceptible to isomerization reaction to obtain cis, trans-isosafrole. In this paper it is presented the eletroxidation of cis, trans-isosafrole from direct isomerization of essential oil of long-pepper, with 99,7 percent of convertion to isosafrole glicol, that it is react by oxidation to convert 99 percent into piperonal with 84,9 percent purity.
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PiperRESUMO
O óleo essencial de pimenta longa (Piper hispidinervum C. DC) é rico em safrol, tornando-o suscetível à reação de isomerização para a obtenção de cis, trans-isosafrol. O presente artigo apresenta a etapa de eletroxidação dos isômeros cis, trans-isosafrol advindos da isomerização direta do óleo essencial de pimenta longa, apresentando 99,7 por cento de conversão em isosafrol glicol, o qual é sujeito à oxidação com conversão de 99 por cento em piperonal, este apresentando 84,9 por cento de pureza.(AU)
The essential oil of long-pepper (Piper hispidinervum C. DC) is rich in safrole, then susceptible to isomerization reaction to obtain cis, trans-isosafrole. In this paper it is presented the eletroxidation of cis, trans-isosafrole from direct isomerization of essential oil of long-pepper, with 99,7 percent of convertion to isosafrole glicol, that it is react by oxidation to convert 99 percent into piperonal with 84,9 percent purity.(AU)
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Técnicas de Química Sintética , Pimenta/químicaRESUMO
As piperáceas brasileiras apresentam propriedades para serem utilizadas, entre outras aplicações, como inseticidas e antifúngicos. Dentre as piperáceas, pode-se citar a Piper hispidinervum C. DC. De suas folhas e dos talos finos extrai-se um óleo essencial rico em safrol, que é utilizado pela indústria como matéria-prima na manufatura, por exemplo, do piperonal. A sequência natural do processo para a obtenção do piperonal é o de submeter o safrol obtido da concentração do óleo essencial à isomerização para seu correspondente isômero estável chamado isosafrol. Apresenta-se neste artigo, por sua vez, a síntese do isosafrol diretamente do óleo essencial de pimenta-longa (Piper hispidinervium C. DC). Este óleo essencial apresenta o safrol como constituinte majoritário, possibilitando a sua isomerização para a produção de isosafrol, que é empregado nas indústrias farmacêuticas e de fragrâncias. O objetivo deste trabalho é o de apresentar a obtenção do isosafrol sem a necessidade da etapa de separação do safrol do óleo essencial de pimenta-longa. Para tanto, foram realizados ensaios de isomerização do óleo essencial, obtendo-se uma solução contendo 79,4 % da mistura cis, trans-isosafrol. Ressalte-se que o óleo essencial continha 86,4 % de safrol, resultando em alto rendimento na sua conversão a cis, trans-isosafrol de 97,1 %.
The Brazilian peppers present proprieties that can be used in fragrance and pharmaceutical industries, for example. One these pepper is long pepper (Piper hispidinervium C. DC.), who its essential oil is rich in safrole. Safrole is an important compound with application in several industries, such as pharmaceutics, cosmetics. After its chemical conversion, for example, it is possible to obtain heliotropin, a fixative agent for fragrances. The sequence to obtain the heliotropin is by safrole isomerization, that, initially, produce isosafrole. In this work, however, presents the synthesis of isosafrole directly from essential oil of Piper hispidinervium C. DC. In this case, the isomerization of essential oil was done getting 79,4 % of cis, trans-isosafrole mixture. The essential oil presented 86,4 % of safrole, resulting in 97,1 % yield to cis, trans-isosafrole.