The Anticonvulsant Effect of Hydroethanolic Leaf Extract of Calotropis procera (Ait) R. Br. (Apocynaceae)

Abstract

A number of currently used drugs have been obtained from medicinal plants which are a major source of drugs. These drugs are either used in their pure form or modified to a semisynthetic drug. Drug discovery through natural product research has been fruitful over the years. Traditionally, Calotropis procera is used extensively in the management of epilepsy. This study is conducted to explore the anticonvulsant effect of a hydroethanolic leaf extract of Calotropis procera (CPE) in murine models. This effect was evaluated using picrotoxin-induced convulsions, strychnine-induced convulsions, and isoniazid- and pilocarpine-induced status epilepticus in mice of both sexes. The results showed that CPE (100-300 mg/kg) exhibited an anticonvulsant effect against strychnine-induced clonic seizures by significantly reducing the duration (p = 0.0068) and frequency (p = 0.0016) of convulsions. The extract (100-300 mg/kg) caused a profound dose-dependent delay in the onset of clonic convulsions induced by picrotoxin (p < 0.0001) and tonic convulsions (p < 0.0001) in mice. The duration of convulsions was reduced significantly also for both clonic and tonic (p < 0.0001) seizures as well. CPE (100-300 mg/kg), showed a profound anticonvulsant effect and reduced mortality in the pilocarpine-induced convulsions. ED₅₀ (~0.1007) determined demonstrated that the extract was less potent than diazepam in reducing the duration and onset of convulsions but had comparable efficacies. Flumazenil-a GABA_A receptor antagonist-did not reverse the onset or duration of convulsions produced by the extract in the picrotoxin-induced seizure model. In isoniazid-induced seizure, CPE (300 mg kg¹, p.o.) significantly (p < 0.001) delayed the onset of seizure in mice and prolonged latency to death in animals. Overall, the hydroethanolic leaf extract of Calotropis procera possesses anticonvulsant properties.

Figure 1

HPLC chromatogram of the 70% hydroethanolic extract of C. procera leaves.

Figure 2

Effect of CPE (30-300 mg/kg, p.o.) and diazepam (0.1-1.0 mg/kg, i.p.) on the duration of strychnine-induced clonic seizures in mice. Data are expressed as mean ± S.E.M. (n = 7). ^∗∗p < 0.01 and ^∗p < 0.05 (one-way ANOVA followed by Tukey's post hoc test).

Figure 3

Effect of CPE (30-300 mg/kg, p.o.) and diazepam (0.1-1.0 mg/kg, i.p.) on frequency (a) and latency (b) of strychnine-induced clonic seizures in mice. Data are expressed as mean ± S.E.M. (n = 7). ^∗∗p < 0.01 and ^∗p < 0.05 (one-way ANOVA followed by Dunnett's post hoc test).

Figure 4

Effect of CPE (30-100 mg/kg, p.o.) and diazepam (0.1-1 mg/kg, i.p.) on the latency to (a) clonic and (b) tonic convulsions in the pilocarpine-induced status epilepticus in mice. Data is presented as mean ± S.E.M. (n = 7); ^∗∗∗p < 0.001; ^∗∗p < 0.01, and ^∗p < 0.05 compared to the vehicle-treated group (one-way ANOVA followed by Dunnett's post hoc test).

Figure 5

Percentage survival of mice for extract (30-300 mg/kg) and diazepam (0.1-1 mg/kg, i.p.). Each point is the mean ± S.E.M. of 7 animals.

Figure 6

Dose-response curve for the anticonvulsant activity induced by the administration of CPE (30-100 mg/kg, p.o.) and diazepam (0.1-1 mg/kg, i.p.) in the pilocarpine-induced seizure test in mice.

Figure 7

Effect of extract (CPE 30-300 mg/kg, p.o.) and diazepam (DZP 0.1-1.0 mgkg⁻¹, i.p.) on the latency to convulsion and survival time curve of isoniazid-induced epilepsy in mice. Data is presented as mean ± S.E.M. (n = 7); ^∗∗∗p < 0.001; ^∗∗p < 0.01 compared to the vehicle-treated group (one-way ANOVA followed by Dunnett's post hoc test).

Figure 8

Effect of CPE (30-300 mg/kg, p.o.) on the latency to (a) clonic convulsion and (b) tonic convulsions in the picrotoxin-induced seizure test in mice. Data are presented as mean ± S.E.M. (n = 7); ^∗∗∗p < 0.001; ^∗∗p < 0.01; compared to the control group (one-way ANOVA followed by Dunnett's post hoc test).

Figure 9

Effect of CPE (30-300 mg/kg, p.o.) on the duration of convulsions in the picrotoxin-induced seizure test in mice. Data are presented as mean ± S.E.M. (n = 7); ^∗∗∗p < 0.001; ^∗∗p < 0.01; ^∗p < 0.05 compared to the control group (one-way ANOVA followed by Dunnett's post hoc test).

Figure 10

Effect of CPE (30-300 mg/kg, p.o.) on the frequency of convulsions in the picrotoxin-induced seizure test in mice. Data are presented as mean ± S.E.M. (n = 7); ^∗∗∗p < 0.001 and ^∗∗p < 0.01 compared to the control group (one-way ANOVA followed by Dunnett's post hoc test).

Figure 11

Effect of flumazenil on the anticonvulsant effect (latency to convulsion) of CPE (100 mg/kg, p.o.). (a) Latency to clonic and (b) latency to tonic convulsion in the picrotoxin-induced seizure test in mice. Data are presented as mean ± S.E.M. (n = 7); ^∗∗∗∗p < 0.0001; ^∗∗∗p < 0.001, and ^∗∗p < 0.01; compared to the vehicle-treated group (One-way ANOVA followed by Dunnett's post hoc test). ^###p < 0.001 compared to the diazepam-treated group.

Figure 12

Evaluation of GABAergic involvement on the duration of (a) clonic and (b) tonic seizures in the picrotoxin-induced seizure test in mice treated with CPE (100 mg/kg, p.o.). Data are presented as mean ± S.E.M. (n = 7); ^∗∗∗∗p < 0.0001; ^∗∗∗p < 0.001, compared to the vehicle-treated group (one-way ANOVA followed by Dunnett's post hoc test). ^###p < 0.001 compared to the diazepam-treated group.

Figure 13

Evaluation of GABAergic involvement on the frequency of (a) clonic and (b) tonic seizures in the picrotoxin-induced seizure test in mice treated with CPE (100 mg/kg, p.o.). Data are presented as mean ± S.E.M. (n = 7); ^∗∗∗∗p < 0.0001; ^∗∗∗p < 0.001; compared to the vehicle-treated group (one-way ANOVA followed by Dunnett's post hoc test). ^###p < 0.001 compared to the diazepam-treated group.