Investigations on the pharmacokinetic properties of <i>Harpagophytum</i> extracts and their effects on eicosanoid biosynthesis in vitro and ex vivo

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.

Section: Resultsmentioning

confidence: 98%

Estimation of the relative antiinflammatory efficacies of six commercial preparations of Harpagophytum procumbens (Devil's Claw)

Ouitas

Heard

2009

“…In vitro studies demonstrated that Hp extracts were able to suppress the biosynthesis of cysteinyl-leukotrienes (Cys-LT; LTC 4 , LTD 4 and LTE 4 ) and TXB 2 when whole blood was stimulated with the calcium ionophore, A23187 (Tippler et al, 1997;Loew et al, 2001). Of further interest was that although the entire extract proved more effective than pure harpagoside alone, the extent of eicosanoid inhibition was found to be as a direct function of the harpagoside concentration, indicating that harpagoside may be the most pharmacologically active component.…”

Section: Preclinical Research (In Vitro and Ex Vivo)mentioning

confidence: 99%

A review of the biological and potential therapeutic actions of Harpagophytum procumbens

Grant

McBean

Fyfe

et al. 2007

Harpagophytum procumbens (Hp), commonly known as Devil's Claw is a perennial plant which thrives in arid conditions. For centuries, it has been used as a traditional treatment for a variety of illnesses, including fevers, skin complaints, arthritis and diseases of the digestive tract as well as an appetite stimulant. Since its introduction to Europe in the early twentieth century, it has become a popular antiinflammatory and analgesic preparation amongst herbalists for supportive or adjuvant treatment of degenerative joint diseases, tendonitis, headache, backache and menstrual pain. The validity of Hp as an effective antiinflammatory and analgesic preparation, particularly in the relief of arthritic symptoms, has been investigated in numerous animal, clinical and in vitro studies. Although some contradictory evidence exists, the majority of animal studies appear to indicate Hp as an effective antiinflammatory and analgesic preparation in the treatment of acute and subacute inflammation. Clinical trials support Hp as a beneficial treatment for the alleviation of pain and improvement of mobility in a variety of musculoskeletal conditions. Analysis of the in vitro and ex vivo studies that currently exist, indicate that Hp has significant effects on numerous proinflammatory markers. However, the exact mechanism(s) by which Hp may reduce inflammation remain to be elucidated.

“…A prerequisite for the analgesic and antiphlogistic effect is the inhibition of eicosanoid biosynthesis. In vitro studies showed that the inhibition of biosynthesis of cysteinyl-LT and thromboxane B 2 strongly depends on the extraction method, the extraction solvent and the harpagoside content (Loew et al, 2001). Extract fractions containing harpagoside had inhibitory effects on in vitro eicosanoid biosynthesis, whereas fractions without harpagoside had no effects or even stimulated cysteinyl-LT biosynthesis.…”

Section: Bioequivalence Of Herbal Products 707mentioning

confidence: 99%

Approaching the problem of bioequivalence of herbal medicinal products

Loew

Kaszkin

2002

100

Herbal medicinal products (HMP) contain exclusively herbal drugs or herbal drug preparations (HDP) and are a complex mixture of different compounds, which may act in an agonistic, synergistic, complementary, antagonistic or toxic way. A specific scientific challenge is for methods to prone the bioequivalence of herbal drug preparations (HDP). Depending on the type of herbal drug preparations, different approaches are possible. If the constituents responsible for therapeutic activity are known, the concept of essential similarity used with chemically defined substances can be fully applied. For extracts with unknown active markers, data on defined chemical constituents are useful for control purposes (charge conformity), but not sufficient to prove bioequivalence. In this case bioassays or pharmacological studies, which measure therapeutically relevant activity, should be used. A phytogeneric is only comparable to the innovator preparation under the following conditions: (i) pharmaceutical equivalence (standardization), (ii) biopharmaceutical equivalence (in vitro dissolution), (iii) bioequivalence with different endpoints (in vitro model, animal model) or (iv) clinical study. An uncritical substitution of herbal drug preparations without considering these scientific criteria should be avoided.