ABSTRACT
Species of the genus Tabebuia are used in traditional medicine and are reported in the literature for their properties against various diseases. The objective of this study was to evaluate the antipyretic, sedative and hypnotic activities of methanol extract of Tabebuia hypoleuca stems (THME) using the Brewer's yeast induced pyrexia, Open field and Sodium thiopental-induced sleeping time tests, respectively. In the Brewer's yeast induced pyrexia test, THME at 500 mg/kg produced a significant (p<0.001) decrease of the fever as from the first hour after administration and was sustained for 4 h. In the Open-field test, THME did not cause any significant change in the number of crossings, rearing, preening and defecation, and either in the time of immobility. Moreover, THME did not produce changes in neither the sleeping latency nor the sleeping time induced by sodium thiopental. These results showed that THME administered orally at 500 mg/kg exerts antipyretic activity, probably mediated by the inhibition of the enzyme cyclooxygenase-2. This study also showed that THME does not exert sedative and hypnotic effects at the doses tested.
Especies del geÌnero Tabebuia se utilizan en la medicina tradicional y se reportan en la literatura por sus propiedades contra diversas enfermedades. El objetivo de este estudio fue evaluar la actividad antipireÌtica, sedante e hipnoÌtica del extracto metanoÌlico de los tallos de Tabebuia hypoleuca (THME) utilizando las pruebas de pirexia inducida por levadura de cerveza, campo abierto y tiempo de suenÌo inducido por tiopental soÌdico respectivamente. En el ensayo de pirexia inducida por levadura de cerveza, THME a 500 mg/kg produjo una reduccioÌn significativa (p<0.001) de la fiebre a partir de la primera hora despueÌs de la administracioÌn y se mantuvo durante cuatro horas. En el ensayo de campo abierto, THME no causoÌ ninguÌn cambio significativo en el nuÌmero de cruces, levantamientos, acicalamientos y defecacioÌn, ni en el tiempo de inmovilidad. AdemaÌs, THME no produjo cambios ni en la latencia de suenÌo, ni en el tiempo de suenÌo inducido por tiopental soÌdico. Estos resultados mostraron que THME administrado oralmente en dosis de 500 mg/kg posee actividad antipireÌtica, mediado probablemente a la inhibicioÌn de la enzima ciclooxigenasa-2. Este estudio tambieÌn demostroÌ que THME no posee actividad sedante e hipnoÌtica en las dosis ensayadas.
Subject(s)
Animals , Male , Rats , Antipyretics/pharmacology , Hypnotics and Sedatives/pharmacology , Plant Extracts/pharmacology , Tabebuia/chemistry , Methanol , Rats, Sprague-DawleyABSTRACT
OBJECTIVE: The aim of this study was to evaluate the antinociceptive activity of the methanol extract of Tabebuia hypoleuca stems (THME). MATERIALS AND METHODS: The animals were divided into 5 groups of 8 mice for each test (negative controls, positive controls, and 3 groups treated with THME at doses of 150, 300, and 500 mg/kg, p.o.). The antinociceptive effect of THME was evaluated using the writhing, formalin, tail flick, and hot plate models in mice. RESULTS: In the writhing test, THME (150, 300, and 500 mg/kg) produced significantly (p < 0.001) fewer writhes induced by acetic acid than in the control group. In the formalin test, the licking time for THME at doses of 300 and 500 mg/kg was signiï¬cantly shorter (p < 0.001) compared to the control group in the first phase of the formalin test, whereas in the second phase only the dose of 500 mg/kg showed an antinociceptive effect. In addition, THME at doses of 300 and 500 mg/kg significantly increased the latency time in the tail flick test (p < 0.05 and p < 0.001, respectively) and in the hot plate test (p < 0.01 and p < 0.001, respectively) compared to the control group. CONCLUSIONS: These results show that THME had antinociceptive activity using several models of nociception, and they suggest that the effect is mediated by the participation of both peripheral and central antinociceptive mechanisms.