The current work compared the relative efficacies of six commercial formulations of H. procumbens. Each formulation was assayed for the content of harpagoside (1), harpagide (2), verbascoside (3) and 8-O-p-coumaroyl harpagide (4) and, based on the recommended dosages, the total daily amounts were determined and used to establish anti-/proinflammatory (A/P) factors. The formulations were compared using ex vivo porcine skin for their activities towards COX-2 by Western blotting. The results showed great variation in the amounts of compounds 1-4 within the six formulations examined. The relative proportions of 1-4 also varied widely between the products and this inconsistency was reflected in the A/P factors, which correlated with the COX-2 expression (R(2) = 0.9496). Although the data support the beneficial antiinflammatory effects from the use of some of the brands tested, others would appear potentially to exacerbate inflammation. To conclude, a ratio based upon the amount and relative proportions of anti- and proinflammatory compounds can be used to predict relative antiinflammatory properties. Also, with access to a diversity of ostensibly similar commercial products, the patient may experience varying therapeutic responses. Finally, current pharmacopoeia monographs, which are generally concerned with a minimum harpagoside content, are inadequate for ensuring the quality of products based on H. procumbens.

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