Evaluation of antipyretic, sedative and hypnotic activities of methanol extract of Tabebuia hypoleuca (C. Wright ex Sauvalle) Urb. stems

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.