RESUMO
The hydroalcoholic extract of Equisetum arvense (HAE) tested at the doses of 200 and 400 mg/kg showed a significant activity on the open-field, enhanced the number of falls in the rota-rod reducing the time of permanence in the bar and increased the sleeping time (46% and 74%) in the barbiturate-induced sleeping time. In the pentylenetetrazole-seizure, it increased the first convulsion latency, diminished the severity of convulsions, reduced the percentage of animals which developed convulsion (50% and 25%) and protected animals from death. On the contrary, in the elevated plus maze, the doses 50, 100 and 150 mg/kg did not affect the evaluated parameters. Thus, HAE presented anticonvulsant and sedative effects. Phytochemical analysis detected the presence of tannins, saponins, sterols and flavonoids.
Assuntos
Anticonvulsivantes/farmacologia , Equisetum , Hipnóticos e Sedativos/farmacologia , Aprendizagem em Labirinto/efeitos dos fármacos , Fitoterapia , Extratos Vegetais/farmacologia , Convulsões/prevenção & controle , Sono/efeitos dos fármacos , Animais , Anticonvulsivantes/administração & dosagem , Anticonvulsivantes/uso terapêutico , Relação Dose-Resposta a Droga , Feminino , Hipnóticos e Sedativos/administração & dosagem , Hipnóticos e Sedativos/uso terapêutico , Masculino , Pentilenotetrazol , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , Caules de Planta , Ratos , Ratos Wistar , Convulsões/induzido quimicamenteRESUMO
The stratum corneum (SC) protein dynamics in the sulfhydryl group regions was studied by electron paramagnetic resonance (EPR) spectroscopy of a covalently attached maleimide derivative spin label. A two-state model for the nitroxide described the coexistence of two spectral components in the EPR spectra. The so-called strongly immobilized component arises from a spin-label fraction with the nitroxide moiety hydrogen-bonded to protein (rigid structure) and the weakly immobilized component is provided by the spin labels with higher mobility (approximately 10 times greater) exposed to the aqueous environment. The relative populations between these two states are in thermodynamic equilibrium. The apparent energetic gain for the nitroxide to form a hydrogen bond with the backbone rather than to be dissolved in the local environment was approximately 10 kcal/mol in the temperature range of 2-30 degrees C and approximately 6 kcal/mol in the range of 30-70 degrees C. Urea treatment caused a drastic increase in the segmental motion of the polypeptide chains that was completely reversible by its removal. Our analyses also indicated that the urea induced unfolding of the SC proteins opening the thiol group cavities. This work can also be useful to improve the spectral analysis of site-directed spin-labeling, especially for a more quantitative description of the nitroxide side chain mobility.