RESUMO
The leaves of Mikania (Asteraceae) species are used in folk medicine as antispasmodic, antiulcerogenic and antirheumatic agents. Phytochemical screening of the crude hydroalcoholic 70% extract (CHE) of Mikania laevigata Shultz Bip. revealed coumarins, terpenes and organic acids. Antiulcerogenic activity of CHE was evaluated, employing different experimental models in rats, to discern the pharmacological mechanism of action. Both the antisecretory and the cytoprotection hypothesis were evaluated. The crude hydroalcoholic extract (1000 mg/kg body wt., vo) decreased the ulcerative lesion index produced by indomethacin, ethanol, stress and reserpine in rats by 85%, 93%, 82% and 50%, respectively. In the pyloric ligation model, a decrease of hydrogenionic concentration (53%) was observed, suggesting that the pharmacological mechanism has a relationship to antisecretory activity. The antisecretory mechanisms of CHE and the coumarin isolated from M. laevigata were confirmed by acid hypersecretion induced by histamine, pentagastrin and bethanechol. Duodenal administration of CHE (1000 mg/kg body wt.) and coumarin (100 mg/kg body wt.) inhibited only the gastric acid secretion produced by bethanecol. These results suggest that both CHE and coumarin may influence the secretion control mediated by the parasympathetic system.
Assuntos
Antiulcerosos/uso terapêutico , Úlcera Duodenal/prevenção & controle , Mikania , Fitoterapia , Extratos Vegetais/uso terapêutico , Animais , Antiulcerosos/administração & dosagem , Anticoagulantes/administração & dosagem , Anticoagulantes/uso terapêutico , Cumarínicos/administração & dosagem , Cumarínicos/uso terapêutico , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Úlcera Duodenal/induzido quimicamente , Etanol , Indometacina , Masculino , Extratos Vegetais/administração & dosagem , Folhas de Planta , Ratos , Ratos Wistar , Reserpina , Estresse FisiológicoRESUMO
The protective effect of a whey protein concentrate (WPC) was studied in three models of stomach ulcerative lesions induction: subcutaneous injection of indomethacin, and stress induced by either intraperitoneal injection of reserpine, or immobilization and holding in the cold (4 degrees C, 2 hours). Adult Wistar rats (300-400 g) were used for acute (single-dose), repetitive, or subchronic (10 days) administration of WPC prior to treatment with the ulcerogenic factors. The best protection was achieved in the indomethacin model for repetitive and subchronic experiments, reaching 50.1% and 44%, respectively, inhibition of the ulcerative lesions, which was significant at 1% probability (P <.01). For the immobilization and cold model, maximum inhibition by WPC was 22.1%, and that for the reserpine model was 23.8%. In both models the inhibition was not significant (P >.05) compared with saline (negative control).