The present investigation was designed to evaluate the analgesic and central nervous system (CNS) depressant activities of the methanolic extract of Ziziphus rugosa Lam. in rat model. The analgesic activity of the extract was examined using acetic acid-induced writhing test (chemically induced pain) at the doses of 200 and 300 mg/kg body weight. Further, the CNS depressant activity of the plant extract was evaluated by open field and hole cross tests at the doses of 300 and 500 mg/kg body weight. In the analgesic activity test, the methanolic extract of Z. rugosa showed significant (p < 0.01) antinociceptive activity in a dose dependent manner. The extract at the dose of 300 mg/kg exhibited 51.87% inhibition of writhing response which was comparable to the reference drug Indomethacin (55.20%). On the other hand, the plant extract also demonstrated significant (p < 0.01) dose-dependent reduction of locomotor and exploratory activities in the open field and hole cross tests. This analgesic and CNS-depressant activity of the extract might be due to the presence of biologically important chemical compounds.
Key words: Central nervous system (CNS)-depressant, antinociceptive, hole cross tests, writhing, locomotor activity.