Neuropharmacological activity of Hydroethanol Leaf Extract of Carica papaya Linn in Swiss Albino Mice

Abstract

Background: One of new medicinal plants that have gained popularity in neurological disorders is Carica papaya. In Nigeria, the leaf extract of C. papaya, either as water decoction or soaked in ethanol, is claimed to be effective in convulsions, sleep disturbances and other neurological conditions. This study investigated the anticonvulsant, anxiolytic, antidepressant, muscle relaxant and sedative activities of the hydroethanol leaf extract of Carica papaya (HELC).

Methods: Different groups of mice received HECL (100 or 200 mg/kg, p.o.), diazepam (3 mg/kg, i.m.) or phenobarbitone (40 mg/kg, i.p.) 30 min. before seizure induction with strychnine (4 mg/kg, i.m.) or picrotoxin (4 mg/kg, i.p.), and seizure latency and duration were measured. For each of Y-maze, chimney, traction, forced swimming and thiopentone-induced sleeping time or forced swimming tests, mice received oral HECL (100 and 200 mg/kg, p.o.) or diazepam (1 mg/kg, i.p.) 30 min. before subjecting them to the test. Data were analysed via one-way ANOVA, with significance at P < 0.05.

Results: HECL significantly and dose-dependently increased latency to strychnine- and picrotoxin-induced seizures, with the 200 mg/kg dose achieving efficacy comparable to diazepam (P < 0.05). HECL, like diazepam caused significant effect on Y-maze performance and chimney tests, whereas there were significant effects in the traction and forced swimming tests. Moreover, HECL did not cause a potentiation of thiopentone-induced sleeping time compared to control. 

Conclusion: Hydroethanol leaf extract of C. papaya demonstrated promise as a potent anticonvulsant at GABAergic and glycinergic inhibitory pathways. By the prolongation of seizure onset, with corresponding reduction in seizure duration, as well as its lack of sedative effect it suggests favorable neurosafety potential. Its effect on muscle tone was minimal on general locomotor; with indication for possible antidepressant effect. These support the traditional use and highlighting its potential as a novel neuroprotective agent.