Antinociceptive and Antioxidant Activities of the Dillenia indica Bark

Dillenia indica Linn. (Dilleniaceae) is widely used as food and reputed in the folk medicine of Bangladesh and India in particular, to relieve pain associated with gastrointestinal disturbance. Methanolic extract of the bark of Dillenia indica Linn. (MDI) was subjected to evaluate for its analgesic and antioxidant properties. The analgesic activity of MDI (200 and 400 mg kg(-1) b.wt. p.o.) was determined for its central and peripheral pharmacological actions using hotplate as well as tail immersion method and acetic acid-induced writhing test with formalin induced pain in mice, respectively. To evaluate antioxidant potential of MDI, total antioxidant activity, scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical as well as total Reactive Oxygen Species (ROS) and assessment of reducing power were used. The extract, at the dose of 200 and 400 mg kg(-1), produced a significant (p<0.05) increase in pain threshold in hotplate and tail immersion methods whereas significantly (p<0.05) reduced the writhing caused by acetic acid and the number of licks induced by formalin in a dose dependent manner. In DPPH and total ROS scavenging method, MDI showed good antioxidant potentiality with the IC50 value of 12.32 +/- 0.16 and 34.72 +/- 0.48 mu g mL(-1), respectively with a good reducing power. The findings of the study suggested that MDI has strong analgesic and antioxidant effects, conforming the traditional use of this plant for pain alleviation to its antioxidant potentiality