EVALUATION OF CNS DEPRESSANT AND ANALGESIC ACTIVITIES OF THE METHANOL EXTRACT OF PIPER LONGUM LINN. LEAVES

Present study reports CNS depressant and analgesic activities of methanol extract obtained from the leaves of Piper longum L (MEPL). CNS depressant activity was evaluated by using open field and hole cross tests at doses of 250 and 500 mg/kg body weight while peripheral analgesic activity was evaluated by using acetic acid induced writhing method and formalin test respectively in rat model at 100 and 200 mg/kg body weight. The results of the statistical analysis showed that the plant extract had significant (p<0.01) dose dependent CNS depressant and analgesic activities. Locomotor activity and exploratory behavior of rats in hole cross and open field test were decreased in the test group comparing the control group indicating CNS depressant effect of the extract which was comparable with the standard drug diazepam. The extract also showed better analgesic effects at both doses characterized by reduction in the number of writhes in the acetic acid-induced writhing model and reduction of licking time in the formalin test when compared to the control group. The extract, at the dose of 200 mg/kg, exerted a maximum of 57.58% inhibition of writhing response and 58.8% inhibition was observed for reference drug Indomethacin. So, the present results suggest that the methanol extract of P. longum leaves possesses remarkable CNS depressant and analgesic activities.