Evaluation of anticonvulsant, sedative and anxiolytic actions of jatropha curcasand allium sativum in Mice.
This study investigated the anticonvulsant, anxiolytic and hypnotic effects of the methanolic extracts of Jatropha curcas Linn (Euphorbiaceae) leaf and Allium sativum Linn (Liliaceae) bulb in mice. It also determined the most active fraction of the two extracts. This was with a view to providing scientific information for their ethnomedicinal claims. The cold methanolic extracts were obtained by maceration. The LD50 of the extracts were determined using Lorke’s method. Doses of (J. curcas: 500, 1000, 1500 mg/kg, per oral (p.o.) and 50, 100, 150 mg/kg, intraperitoneal (i.p.) and A. sativum 500, 1000, 2000 mg/kg, p.o., and 200, 400, 800 mg/kg, i.p.) were screened for anxiolytic, hypnotic and anticonvulsant activities. The anxiolytic effect was evaluated in Open Field Test (OFT), Elevated-Plus Maze (EPM) and Holeboard (HB), the hypnotic effect of the extracts was determined in pentobarbital - induced sleep model where the sleep latency and total sleeping time were assessed, while the anticonvulsant test was carried out using strychnine (STR), pentylenetetrazole (PTZ), picrotoxin (PTX), pilocarpine (PILO) and maximum electroshock (MES) - induced convulsion models. J. curcas extract with most potent anticonvulsant effect was separated into n-hexane, ethylacetate and butanol fractions. Each fraction (n-hexane 10, 15, 20 mg/kg, i.p., ethylacetate 10, 20 40 mg/kg, i.p. and butanol 100, 200 300 mg/kg, i.p.). Each fraction was evaluated for anxiolytic, hypnotic and anticonvulsant effects (PTZ, PTX and PILO - the models with highest anticonvulsant protection from the earlier models). The mechanism of action of the ethylacetate fraction that showed the highest anticonvulsant activity to pentylenetetrazole - induced convulsion was evaluated using appropriate antagonist, flumazenil. The results were analysed using one-way ANOVA followed by the Student- Newman keul-test. The oral LD50 of J. curcas and A. sativum were 3808 and ≥ 5000 mg/kg, respectively, and interperitoneally 346 and 2154 mg/kg, respectively in mice. The LD50 of n-hexane, ethylacetate and butanol fractions of J. curcas also gave 49, 89 and 775 mg/kg, i.p. respectively in mice. The effect of the extracts in the OFT significantly (p<0.05) decreased locomotor, rearing and grooming activities and in HB there was a significant (p<0.05) decrease in number of head dips suggesting that the extracts possessed central nervous system depressant activity. The extracts also reduced sleep latency and prolonged sleeping time. The results showed that the extract of J. curcas gave a better anticonvulsant protection than A. sativum in PTX and PTZ – induced convulsion and significantly (p < 0.05) prolonged onset of clonic tonic seizures and death latency. In the PILO-induced convulsion the duration of seizure was significantly (p < 0.05) reduced and death latency was significantly prolonged. The three fractions of J. curcas that were evaluated showed varying degrees of anxiolytic, hypnotic and anticonvulsant effects. The ethylacetate fraction was found to be the most potent compared to the n-hexane and butanol fractions. The mechanism of action of the ethylacetate fraction is due to its interaction with GABA – benzodiazepine receptors. The study concluded that J. curcas and A. sativum possessed anxiolytic, hypnotic and anticonvulsant activities. The anticonvulsant activity of J. curcas was higher than that of A. sativum, thus providing scientific evidence in support of the traditional use of the plant in the management of epilepsy.