RESUMO
Investigation of the endophytic fungi Nigrospora sphaerica, Nigrospora oryzae, and Pseudofusicoccum stromaticum MeOH fractions isolated from the leaves of Vochysia divergens, a medicinal species from the Brazilian Pantanal, led to the identification of five compounds, namely a new compound (1E,8Z)-10,11-dihydroxy-5,5,8-trimethyl-4-oxocycloundeca-1,8-diene-1-carbaldehyde (1) and four known compounds: 5-methylmellein (2), sclerone (3), daldinone A (4), and lasiodiplodin (5). All compounds were identified using spectroscopic methods, and 1 was corroborated with mass spectrometry, while the known compounds were compared with data in the literature. The relative configuration of compound 1 was determined based on theoretical conformational studies as well as the J experimental values between the hydroxymethyne hydrogens. The antimicrobial activity of the compounds was evaluated. Promising results were obtained for compounds 2, 4, and 5 since they inhibited the bacterium Pseudomonas aeruginosa, an opportunistic pathogen, suggesting the potential of these microorganisms as a source of new antibacterial agents.
Assuntos
Anti-Infecciosos , Anti-Infecciosos/química , Fungos/metabolismo , Antibacterianos/farmacologia , Antibacterianos/metabolismo , Folhas de Planta/microbiologia , Brasil , Endófitos/metabolismoRESUMO
Chemical investigation of the stems of Dulacia egleri resulted in the isolation of eglerisine (1: ), a compound with a rare sesquiterpenoid tropolone skeleton. Its structure was determined by analysis of spectrometric and spectroscopic data, including HRESIMS, 1D, and 2D NMR. The antiproliferative effects of eglerisine were tested in human leukemia lineages. In the Kasumi-1 lineage, an acute myeloid leukemia cell line, eglerisine reduced cell metabolism, as determined by the resazurin assay. Eglerisine did not induce cell death by either apoptotic or necrotic mechanisms. However, a reduction of the absolute number of cells was observed. Eglerisine induced cell cycle arrest after 72 h of treatment by phosphorylation of H2AX histone, reducing the S phase and increasing the G2 phase of the cell cycle.
Assuntos
Antineoplásicos Fitogênicos/isolamento & purificação , Proliferação de Células/efeitos dos fármacos , Olacaceae/química , Extratos Vegetais/farmacologia , Sesquiterpenos/isolamento & purificação , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Histonas/metabolismo , Humanos , Leucemia Mieloide Aguda , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Sesquiterpenos/química , Sesquiterpenos/farmacologiaRESUMO
In this study, a quantum approach is presented to explain microwave-enhanced reaction rates by considering the tunneling effects in chemical reactions. In the Arrhenius equation, the part of the Hamiltonian relative to the interaction energy during tunneling, between the particle that tunnels and the electrical field defined in the medium, whose spatial component is specified by its rms value, is taken into account. An approximate evaluation of the interaction energy leads to a linear dependence of the effective activation energy on the applied field. The evaluation of the rms value of the field for pure liquids and reaction mixtures, through their known dielectric properties, leads to an appreciable reduction in the activation energies for the proton transfer process in these liquids. The results indicate the need to move toward the use of more refined methods of modern quantum chemistry to calculate more accurately field-induced reaction rates and effective activation energies.
RESUMO
The study about Eugenia dysenterica led to the isolation of 3-acetyl-urs-12-en-28-oic (1), 3-acetyl-olean-12-en-28-oic acid (2) and isoquercetin (3) from the stem barks, and of 3-O-ß-glucopyranosyl-ß-sitosterol (4), methyl 3-hydroxy-4-methoxybenzoate (5), methyl 4-hydroxyphenyl propionate (6), E-methyl-4-hydroxycinnamate (7), quercetin-3-O-(6êê-O-galloyl)-ß-d-glucopyranoside (8) and quercetin-3-O-ß-d-galactopyranoside (9) from the leaves. The structures 1-9 were set through the analysis of their NMR spectroscopic data. Compounds 2, 3 and 5-8 were reported for the first time in the Eugenia genus. Compound 8 reduced cell viability and presented IC50 values 40.3 and 36.7 µM, for the CCRF-CEM and the Kasumi-1 cells, respectively.
Assuntos
Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Eugenia/química , Leucemia/tratamento farmacológico , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Flavonoides/química , Flavonoides/farmacologia , Galactosídeos/química , Galactosídeos/farmacologia , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Ácido Oleanólico/química , Casca de Planta/química , Extratos Vegetais/química , Folhas de Planta/química , Quercetina/análogos & derivados , Quercetina/química , Quercetina/farmacologiaRESUMO
A new orbitide named [1-8-NαC]-zanriorb A1 (1) was isolated and characterized from the leaves of Zanthoxylum riedelianum using NMR and mass spectrometry. The absolute configuration of the amino acids was determined using Marfey's method on the acid hydrolysates. Compound 1 induced cell death by apoptosis in Jurkat leukemia T cells (IC50 218 nM).
Assuntos
Apoptose/efeitos dos fármacos , Peptídeos Cíclicos/isolamento & purificação , Folhas de Planta/química , Zanthoxylum/química , Brasil , DNA/análise , Humanos , Células Jurkat , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologiaRESUMO
Microwave heating technology is dependent on the dielectric properties of the materials being processed. The dielectric properties of H2SO4, H3PO4, ClSO3H, and H3CSO3H were investigated in this study using a vector network analyzer in an open-ended coaxial probe method at various temperatures. Phosphoric and sulfuric acids presented higher loss tangents in the frequency range 0.3-13 GHz, reflecting greater mobility of the ions and counterions. The acids were employed as catalysts in microwave-assisted homogeneous transesterification reactions for the production of methylic and ethylic biodiesel. The effects of catalyst concentration, alcohol to oil molar ratio, and irradiation time on biodiesel conversions were investigated. The results showed a significant reduction in the reaction time for microwave-assisted transesterification reactions as compared to times for conventional heating. Also, despite its higher loss tangent, it was observed that H3PO4 leads to lower conversion to biodiesel, which can be explained by its lower carbonyl protonation capacity.