Gmelina arborea Roxb. (Verbenaceae) is greatly valued plant reported in Indian traditional system of medicine for various ailments. In this study, anticonvulsant and antioxidant activity of methanolic extract of stems (MES) of Gmelina arborea Roxb. was investigated. Protective effects were evaluated in pentylenetetrazole (PTZ) (60 mg/kg, s.c.) and strychnine (STR) (2 mg/kg, i.p.) induced seizure models in adult albino mice (250 mg/kg and 500 mg/kg) using diazepam as a standard.
Total phenolics and flavonoids content in MES were determined and antioxidant activity was evaluated by 1,1-diphenyl-2- picryl- hydrazyl (DPPH) radical scavenging activity, scavenging of hydrogen peroxide and through reducing power assay. The onset and duration of seizures (tonic-clonic convulsions), mortality rate and number of mice convulsing or not convulsing within the observation period were noted in PTZ and STR induced seizure models. MES showed good reductive capability and free radical scavenging effects with IC50 47.47 µg/ml for DPPH radical assay and 97.33 µg/ml for hydrogen peroxidescavenging in a dose dependent manner.MES at the dose of 500 mg/kg, exhibited maximum delay in onset of convulsions (8.188 min in PTZ and 11.81 min in STR induced seizures) in both the models with increased latency period.
The suppression of seizures by MES (500 mg/kg) might be observed due to enhanced gamma amino butyric acid neurotransmission in PTZ induced animals. The constituents of MES might also have glycine inhibitory potential to impart protection in STR induces seizures in our study. Further considerable presence of flavonoids and phenolic have provided good antioxidant activity as a supportive underlying mechanism for anticonvulsant effects. This study justifies the multilevel therapeutic uses of stem bark and heartwood of G. arborea in Indian system of medicine.
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