Inhibitory Effect of the root of Polygala tenuifolia on Bradykinin and COX 2-Mediated Pain and Inflammatory Activity

Purpose: To gain insight into the mechanisms of analgesic and anti-inflammatory activities of the root extract of Polygala tenuifolia. Methods: Polygala tenuifolia was extracted with 70 % methanol and tested for analgesic and antiinflammatory activities (0.1, 1, 10 and 100 mg/kg) using the following models: acetic acid-induced writhing, rat paw edema, bradykinin inhibtion with rat ileum, and prostaglandin assay. Results: Administration of the Polygala tenuifolia extract at 100 mg/kg dose produced significant analgesic effect on acetic acid-induced writhing (97 % inhibition) but its effect in the tail-flick test was not significant (p < 0.05). In addition, the extract exerted significant anti-inflammatory effect in the rat paw edema model (8 to 33 % inhibition) at doses ranging from 0.1 100.0 mg/kg). A significant inhibitory action (53%) on the bradykinin-mediated contractions of rat ileum was also observed. Furthermore, the extract significantly (p < 0.05) inhibited the production of lipopolysaccharides-induced 6-keto-PGF1 by 28% in macrophage cultures. Conclusion: These results provide evidence that the Polygala tenuifolia root extract exerts analgesic and anti-inflammatory effects via its significant inhibitory effect on acetic acid writhing test, bradykinin-mediated actions as well as on 6-keto-PGF1 induction.