RESUMO
The central nervous system (CNS) depressant and anticonvulsant activities of iso-6-spectaline (SPEC) were investigated in animal models. The SPEC from Senna spectabilis var. excelsa (Schrad) (0.1, 0.5 and 1.0 mg/ kg) injected by oral route (p.o.) in mice caused a significant decrease in the motor activity up to 30 days after the administration and in the dose of 1.0 mg/kg significantly reduced the remaining time on the Rota-rod apparatus. Additionally, SPEC (0.1, 0.5 and 1.0 mg/kg, p.o.) was also capable of promoting increase of latency for development of convulsions induced by pentylenetetrazole. This SPEC was also capable of promoting an increase of latency for development of convulsions induced by picrotoxin at highest dose. In the same way, the anticonvulsant effect of SPEC was affected by pretreatment with flumazenil, a selective antagonist of the benzodiazepine site of the GABA(A) receptor. These results suggest possible CNS depressant and anticonvulsant activities in mice that needs further investigation.
RESUMO
True "timbós" from the Brazilian Amazon region, plants belonging to the genus Derris of the Leguminosae family, have there considerable importance, because they contain rotenoids which are toxic to fish and mammals. The aim of the study was to establish the lethal doses (LD50) for three phylogenetical different species of fish and also for the rat. The lethal dose for Collosoma macropomum (tambaqui) was 2.6 mg/ml, for Oreochromis niloticus (tilápia) 4.8 mg/ml, for Plecostomus sp (cascudo) 14.2 mg/ml and for Rattus norvegicus 100 mg/kg. The large differences between the lethal doses for the fish and the one for the rat are possibly due to different barrier tissues against the action of rotenoids in the mammal when given orally.
Os "timbós verdadeiros" (plantas do gênero Derris), originários da Amazônia Brasileira, tem demonstrado importância crescente por produzirem uma classe de compostos flavonoídicos relacionados à rotenona, que possuem atividade tóxica para peixes e mamíferos. Neste estudo foi determinado a dose letal 50% (DL50) do extrato alcoólico do pó de Derris spp para três espécies de peixes filogeneticamente diferentes e um mamífero roedor (rato). As DL50 de 2,6 microgramas/ml para Collosoma macropomum (tambaqui), 4,8 microgramas/ml para Oreochromis niloticus (tilápia), 14,2 microgramas/ml para Plecostomus sp (cascudo) e DL50 de 100,0 mg/kg para Rattus norvegicus (rato) denotam acentuadas diferenças entre os valores de DL50, principalmente entre os peixes e o rato. Isto possivelmente é devido a fatores farmaco-cinéticos que se relacionam com as diferentes barreiras teciduais encontradas pelos rotenóides quando administrados pela via oral em mamíferos.