ABSTRACT
Abstract: INTRODUCTION: The inflorescences of Tilia americana var. mexicana are used as an infusion in Mexican traditional medicine due to their tranquilizing effects; however, pharmacological and phytochemical studies of the leaves are lacking. OBJECTIVE: In this research, the anxiolytic and sedative-like efficacy of the Tilia americana var. mexicana leaves was compared to that obtained with its inflorescences and flavonoids therein identified, as well as the possible mechanism of action. METHODS: The sorted and dried inflorescences and leaves were macerated subsequently in hexane, ethyl acetate and methanol. The methanol extracts were qualitative- and quantitative-analyzed by HPLC, using commercial flavonoids standards selected on the basis of their previously reported presence in Tilia species. The pharmacological activity was evaluated in CD-1 mice in the tests: open-field, elevated plus-maze, hole-board, and the sodium pentobarbital-induced sleep potentiation test. In regard to the mechanism of action, participation of benzodiazepine and 5-HT1A serotonin receptors was tested with the respective antagonists: flumazenil and WAY100635. RESULTS: The presence of quercetin, rutin and isoquercitrin was confirmed in the extracts of the inflorescences and leaves. The anxiolytic-like effects were the same between the two organs, which were inhibited in the presence of flumazenil and WAY100635. DISCUSSION AND CONCLUSION: Our results provide evidence that the extracts of the leaves of T. americana var. mexicana are as efficacious as the inflorescences to produce anxiolytic and sedative-like effects, where flavonoids like quercetin, rutin and isoquercitrin are partially responsible for these activities by the involvement of GABA/BDZ and 5HT1A serotonergic receptors.
Resumen: INTRODUCCIÓN: En la medicina tradicional mexicana, la infusión de inflorescencias de Tilia americana var. mexicana es utilizada por sus efectos tranquilizantes; sin embargo, los estudios farmacológicos y fitoquímicos de sus hojas son deficientes. OBJETIVO: En esta investigación, la eficacia ansiolítico-sedante de las hojas de T. americana var. mexicana se comparó con la obtenida con las inflorescencias y los flavonoides previamente identificados; se analizó además el posible mecanismo de acción. MÉTODOS: Inflorescencias y hojas separadas y secas se maceraron sucesivamente en hexano, acetato de etilo y metanol. Los extractos metanólicos se analizaron cualitativa y cuantitativamente por HPLC usando estándares comerciales de flavonoides previamente reportados en especies de Tilia. La actividad farmacológica se evaluó en ratones CD-1 en las pruebas de campo abierto, cruz elevada, tablero con orificios y la prueba de potenciación de hipnosis inducida por pentobarbital sódico. Respecto al mecanismo de acción, la participación de los receptores de benzodiazepinas y 5-HT1A de serotonina se examinó utilizando los antagonistas flumazenil y WAY100635, respectivamente. RESULTADOS: La presencia de quercetina, rutina e isoquercitrina se confirmó en los extractos de inflorescencias y hojas, donde se confirmó el efecto como ansiolítico, el cual fue inhibido en la presencia de flumazenil y WAY100635. DISCUSIÓN Y CONCLUSIÓN: Nuestros resultados dan evidencia de que las hojas de T. americana var. mexicana son tan eficaces como las inflorescencias para producir efectos ansiolítico-sedantes, donde los flavonoides quercetina, rutina e isoquercitrina son responsables parciales y se involucra la participación de los receptores GABA/BDZ y 5HT1A de serotonina.
ABSTRACT
The aim of this study is to develop a simple and specific HPLC method using vitexin as the internal standard to investigate the pharmacokinetics of isoquercitrin (ISOQ) after three different doses administrated intravenously to rats. The pharmacokinetic parameters were calculated by both compartmental and non-compartmental approaches. The results showed that ISOQ fitted a three-compartment open model. The values of AUC increased proportionally within the range of 5-10 mg·kg-1. Moreover, a half-life, b half-life, ªCL, MRT0-t and MRT0→∞ of ISOQ in rats showed significant differences between 20 mg·kg-1 and other doses, indicating that ISOQ presented dose-dependent pharmacokinetics in the range of 5-10 mg·kg-1 and non-linear pharmacokinetics at higher doses.
O objetivo deste estudo é desenvolver um método simples e específico de HPLC usando vitexina como padrão interno para investigar a farmacocinética do isoquercitrina (ISOQ) após três doses diferentes administradas por via intravenosa a ratos. Os parâmetros farmacocinéticos foram calculados pelas abordagens compartimental e não compartimental. Os resultados mostraram que ISOQ se encaixa no modelo de três compartimentos. Os valores de AUC aumentaram proporcionalmente na faixa de 5-10 mg·kg-1. Além disso, a meia-vida, b meia-vida, ªCL, MRT0-t and MRT0→∞ de ISOQ em ratos mostraram diferenças significativas entre 20 mg·kg-1 e outras doses, o que significa que ISOQ apresenta farmacocinética dose-dependente no intervalo de 5-10 mg·kg-1 e farmacocinética não linear em doses mais elevadas.