RESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Dorstenia arifolia is a plant that has been used in the folk medicine to produce hypnotic, sedative and ansiolitic effects but the pharmacological properties have not yet been studied. In addition, the smoke of its rhizome is reputed to induce lethargic sensation. AIMS OF THE STUDY: The present study investigated possible activities of the methanol extract (ME) of Dorstenia arifolia rhizome on the central nervous system (CNS). MATERIALS AND METHODS: ME was tested for sedative, hypnotic and anticonsulsant effects using locomotor activity evaluation, pentobarbital-induced sleeping time and pentylenetetrazol (PTZ)-induced convulsion, respectively. RESULTS: Intraperitoneal administration of ME (10 and 50mg/kg) significantly decreased locomotor activity from 205.2+/-25.6 movements/min (DMSO) to 112.1+/-18.4 (P<0.05) and 114.9+/-16.9 (P<0.05), respectively. Flumazenil (10 mg/kg), an antagonist of GABA(A) receptor, prevented the ME-induced sedation. Treatment with ME (50mg/kg) significantly increased the duration of pentobarbital-induced sleeping time from 41.0+/-2.3 to 57.9+/-2.9 min (P<0.05). The latencies to seizures after intraperitoneal injection of PTZ was recorded and compared between groups. ME promoted a significant protection of PTZ-induced seizures and mortality in a dose-dependent manner. CONCLUSIONS: Our findings indicate that ME of Dorstenia arifolia rizhome has pronounced central effects, and that the sedative and anticonvulsant activities may be related to a facilitation of the GABAergic transmission.
