Analgesic and Antioxidant Activity of the Hydromethanolic Extract of Mikania scandens (L.) Willd. Leaves

Problem statement: Mikania scandens (L.) Willd., a medicinal plant, is popularly used as herbal remedy for various ailments in Bangladesh. But the scientific basis for its medicinal use especially in pain and inflammation remains unknown. Therefore, the present study was designed to evaluate analgesic and antioxidant potential of the hydromethanol extract of the leaves of the plant. Approach: The analgesic activity was determined for its central and peripheral pharmacological actions using hotplate and tail immersion method and acetic acid-induced writhing test in mice respectively. The hydromethanol extract was also investigated for its antioxidant action using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, Nitric Oxide (NO) scavenging and reducing power assays. Results: The extract, at the dose of 250 and 500 mg kg^-1, produced a significant (p<0.05) increase in pain threshold in hotplate and tail immersion methods in a dose dependent manner. In acetic acid-induced writhing test, the extract (500 mg kg^-1) produced a maximum of 53.73% inhibition (p<0.001) of writhing reaction compared to the reference drug Diclofenac-Na (76%). A dose dependent scavenging of DPPH radical and NO was observed with good reducing power with the extract. In DPPH radical scavenging assay, the IC₅₀ value of the extract was 375.40 μg mL^-1 while the IC₅₀ value for the reference ascorbic acid was 55.89 μg mL^-1. The IC50 values of the extract and ascorbic acid were 220.43 and 125.10 μg mL^-1, respectively in NO scavenging assay. Conclusion: The findings of the study suggested that the extract from Mikania scandens has strong analgesic and antioxidant effects.