Central Nervous System Depressant, Analgesic and Antidiarrheal Effects of the Seed Extracts of Dimocarpus longan Lour in Rats

Purpose: To assess the central nervous system (CNS) depressant, analgesic and antidiarrheal activities of the dried seed crude extracts of Dimocarpus longan Lour in rodents.Methods: Selected pharmacological effects of the ethanol (ENLS), petroleum ether (PELS), chloroform (CHLS) and ethyl acetate (EALS) extracts of D. longan fruit seeds were investigated. CNS depressant activity was evaluated by open field and hole cross tests; analgesic activity by acetic acid-induced writhing test and formalin-induced licking test; and anti-diarrheal activity was assessed in castor oil and magnesium-induced diarrhea rat model. The extracts were given orally in a rat model at doses of 200 and 300 mg/kg body weight. Normal saline served as control in all experiment. In CNS depressant test, diazepam (1 mg/kg) was used as reference drug while indomethacin (10 mg/kg) and loperamide(2 mg/kg) were used as standard drugs in analgesic and antidiarrheal tests, respectively.Results: In hole cross method, EALS showed the most effective depressant effect, viz, 1.17±0.17 for 200 mg/kg dose and 0.83±0.31 number of movements for 300 mg/kg dose after 120 min (p < 0.01), whereas in the open field test, all the extracts exhibited significant (p < 0.01) depressant effect in relation to positive control, diazepam. In acetic acid-induced pain test, PELS gave the lowest number of writhing (2.83±0.307) and the highest inhibition (88.45 %, 300 mg/kg dose) which was statistically significant. All the extracts also significantly (p < 0.01) suppressed licking activity in both phases of the formalin-induced licking test, in contrast to indomethacin. In the antidiarrheal tests, diarrheal suppression was highest at 300 mg/kg dose for all the extracts, compared with loperamide in both castor oil and magnesium sulphate induced diarrhea model.Conclusion: The extracts of Dimocarpus longan tested demonstrated significant CNS depressant, analgesic and antidiarrheal activities in a rodent model.Keywords: Dimocarpus longan Lour, CNS depressant, Analgesic, Anti-diarrheal