A methanolic extract of Harpagophytum procumbens as well as harpagoside and harpagide were tested
as direct inhibitors of cyclooxygenase-2 enzyme (COX-2). The H. procumbens extract demonstrated
direct inhibition (68%) of COX-2 enzyme. The concentration of harpagoside and harpagide equivalent to
that found in the extract (3 and 1% respectively) contributed 1.5 and 13% to this inhibition. Results
indicated direct COX-2 enzyme inhibition by the H. procumbens extract due to possible synergistic
activity of active components in the extract, which include harpagide and harpagoside.