Toxicological Evaluation of the Methanol Extract of Gmelina arborea Roxb. Bark in Mice and Rats.

Objective: The present study was designed to evaluate acute and repeated dose toxicity of the methanol extract (ME) of the Gmelina arborea stem bark. Materials and Methods: For the acute toxicity study, ME of G. arborea was orally administered to Swiss albino mice at a dose range of 300-5000 mg/kg. For the repeated dose toxicity study, the Wistar rats of either sex were orally administered with ME of G. arborea at the doses of 300, 1000, and 2000 mg/kg/day for a period of 28 days. The effects on body weight, food and water consumption, organ weight, hematology, clinical chemistry as well as histology were studied. Results: The administration of ME from the G. arborea bark at 300-5000 mg/kg did not produce mortality or significant changes in the clinical signs. The no-observed adverse effect level (NOAEL) of ME was 5000 mg/kg. There were no significant differences in the general condition, growth, organ weights, hematological parameters, clinical chemistry values, or gross and microscopic appearance of the organs from the treatment groups as compared to the control group. Conclusion: ME of G. arborea was found safe in acute and repeated dose toxicity studies when tested in mice and rats.