Vitamin Expert

Devils Claw root Facts

Latin name: Harpagophytum procumbens

Pharmacopoeial name: Harpaophyti radix

Other names; grapple plant, wood spider

About Devils Claw

Harpagophytum procumbens is a weedy, perennial tuberous plant with visually striking fruits. The fruits have numerous characteristically long protrusions with sharp, grapple-like hooks, as well as two straight thorns on the upper surface, leading to the colloquial name of Devil’s Claw. Flowers are a deep mauve-pink colour with a yellow and white throat while the leaves are blue-green and usually irregularly divided into several lobes. The creeping stems, sprout annually from the persistent primary tubers which can extend up to 2m deep. The stems give rise to several secondary storage tubers and it is these secondary tubers that are harvested for their medicinal properties. The species name Harpagophytum is derived from the Greek ‘harpago’ which translates to ‘the grappling hook’.

Harpagophytum procumbens is an important traditional medicinal plant growing in the Kalahari region of southern Africa. The use of H. procumbens was prominent amongst the indigenous San and Khoi people of South Africa; its use was further adopted by Bantu-speakers. Recent scientific studies show that extracts of the secondary tubers of H. procumbens are effective in the treatment of degenerative rheumatoid arthritis, osteoarthritis, tendonitis, kidney inflammation, heart disease, dyspepsia and loss of appetite (1).
Compounds include; iridoids; harpagoquinones,aminoacids,flavonoids, phytosterols and carbohydrates (2).


Anti-inflammatory activity

In 1957,it was shown that subcutaneous injection and oral ingestion of an infusion of H. procumbens caused significant reduction in the swelling of arthritic joints. It was concluded that H. procumbens contained a potent anti-inflammatory or anti-rheumatic substance and subsequent tests were undertaken to determine whether the isolated constituent, harpagoside, yielded the same results. The results were positive but the whole plant extract showed better activity (3).

Since then numerous studies have been undertaken to prove in vitro and in vivo inflammatory activity for H. procumbens extracts and/or isolated compounds. It is postulated that the efficacy of H. procumbens in reducing pain and inflammation associated with rheumatoid arthritis and osteoarthritis can be explained by its ability to block the production of inflammatory mediators such as PGE2 (4). However, some reports on the anti- inflammatory effect of H. procumbens extracts are inconsistent, and differences had widely been attributed to the extraction procedure, geographical source of the crude drug and the fractions of constituents (5).

Several clinical studies have been performed to determine the effectiveness of H. procumbens for its use as anti-inflammatory, general analgesic (commonly for lower back pain) and anti-rheumatic agent. Moussard et al.(1992) investigated the effect on arachidonic acid metabolism after daily administration 2.0 g powder (500mg/capsule) containing 3% total glucoiridoids to healthy volunteers for21 days (6).They concluded that H. procumbens does not have a similar effect as NSAIDs in healthy humans as statistically significant changes in the biochemical parameters monitored were not noted.

To determine the effectiveness on lower back pain, Harpagophytum extract was administered in two daily doses of 600 and 1200mg containing 50mg and 100 mg of harpagoside, respectively, and compared to placebo. This randomised double-blind study took place over 4 weeks and subjects with chronic susceptibility to back pain and current exacerbations with intense pain were included. Out of 183 subjects that completed the trial, six in the 600mg and 10 in the 1200mg were reported ‘pain-free’ without using Tramadol (rescue pain medication). However, data analyses suggested that the 600mg group reaped more benefit where less severe pain and no radiation or neurological deficit was present. The patients with more severe pain tended to use more Tramadol but not to the maximum permitted dose (7).

A single group, open, 8-wk clinical study was conducted in the United Kingdom on 259 patients suffering from arthritis and other rheumatic conditions (AORC) where pain (rated 2–7 out of 10) was present at least 2 days per week in the affected area during the previous 8 weeks. Tablets containing 480mg of H. procumbens dried extract were self-administered every morning and evening (960mg/d) with meals and the effectiveness assessed in 207 patients. From baseline to week 4 and 8, a significant reduction was noted in the global mean scores for pain, stiffness and function. From baseline to week 8, mean scores for pain in the back, hip, knee, hand, wrist and elbow were significantly reduced. A rating of good or excellent was recorded by 54% of patients and perceived in 53% of patients by investigators. The dosage form was well tolerated and only 4.2% discontinued treatment due to adverse events, mainly gastrointestinal complaints. Concomitant analgesic use was assessed in 154 patients: 44.8% reduced their dosage, 26.0% stopped taking analgesics, 16.9% took the same dosage and 9.1% increased their dosage (8).

A review of the clinical trial literature from 1966 to 2006 on the efficacy of H. procumbens in the treatment of osteoarthritis was reported by Brien et al (9), who identified 14 relevant studies: eight observational studies; two comparator trials (one open, the other randomised);and four double-blinded, placebo- controlled, randomised controlled trials. The authors found that while many of the published trials did not conform to important methodological quality criteria, the data from the higher quality studies indicated that Devil’s Claw appeared effective in the reduction of the main clinical symptom of pain. The assessment of clinical evidence for safety was limited by the small populations included in the clinical studies.

#A Cochrane Review of herbal medicine used to treat lower back pain found two high-quality clinical trials utilising H. procumbens. Strong evidence for short-term improvements in pain for daily doses of H. procumbens standardised to 50mg or 100mg harpagoside was found. Another high-quality trial demonstrated relative equivalence of the H. procumbens product to 12.5mg/d of the pharmaceutical anti-inflammatory rofecoxib (10).

Anti-oxidant activity

The anti-oxidant activity of H. procumbens was determined using the Trolox equivalent anti-oxidant capacity (TEAC) assay. The results showed that H. procumbens extract was particularly rich in water-soluble anti-oxidants, but harpagoside did not contribute significantly to its anti-oxidant activity (11).

Anti-diabetic activity

It is reported that H. procumbens secondary tuber is used in some communities to treat adult-onset, type-2 diabetes (12).

Antifungal activity

There are reports that supercritical carbon dioxide extracts of H. procumbens inhibits Candida. However, harpagoside alone was not effective , suggesting the existence of synergy between the biologically active constituents (13).

Antimalarial activity

Clarkson et al. studied the effect of two diterpenes isolated from H. procumbens extract to determine the selectivity of their antiplasmodial activity. Both displayed significant in vitro antiplasmodial activity against both chloroquine-resistant and chloroquine-sensitive strains of P. falciparum (14).

Cardiovascular activity

One study suggests that crude H.procumbens methanol extract exhibited protective effects in some experimental arrhythmias (15). Harpagophytum procumbens decreases heart rate and arterial blood pressure in rats. It has been suggested that it may cause QT prolongation and abnormal heart rhythms as well as influence calcium currents (verapamil-like effect). Therefore, patients treated for cardiovascular disorders should be warned about possible side- effects, though cardiovascular effects seem unlikely based on current data (16).


Excessive doses may interfere with existing treatments for cardiac disorders. It should not be taken in pregnancy.

Keywords: Anti-inflammatory activity, antioxidant. Antidiabetic; antifungal; antimalarial; cardiovascular


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16. EMEA (European Medicines Agency), 2009/