Evaluation of analgesic, anti-inflammatory and CNS depressant activities of methanolic extract of Lawsonia inermis barks in mice

Objectives: The study was carried out to assess the analgesic, anti-inflammatory, and CNS depressant activity of the methanolic extract of the Lawsonia inermis barks (MELIB). Materials and Methods: Anti-inflammatory effects of MEBLI were studied using carrageenan-induced inflammatory method at the dose of 300 and 500 mg/kg b.wt., p.o. Analgesic activity was measured using acetic acid-induced writhing model and formalin-induced licking and biting in mice. The CNS depressant activity was evaluated by observing the reduction of locomotor and exploratory activities in the open field and hole cross tests at a dose of 300 and 500 mg/kg body weight. Results: Statistical analysis showed that dose of 500 mg/kg exhibited higher analgesic activity against acetic acid-induced pain in mice than the standard drug diclofenac sodium. Furthermore, doses of 300 and 500 mg/kg caused higher percent of protection (91.16% and 95.03%, respectively) of licking and biting of formalin-induced mice than diclophenac sodium (70.72%). The Lawsonia inemis methanolic extract (300 and 500 mg/kg) also exhibited sustained inhibition (54.97% and 65.56%) of paw edema at the 4(th) hour compared with standard indomethacin (74.17%). Besides, the plant extract also had significant (p<0.05) dose-dependent CNS depressant activity. Conclusion: this study recommends that the methanolic extract of Lawsonia inermis barks has significant analgesic, anti-inflammatory, and CNS depressant properties.