The indigenous inhabitants of Southern Africa, mainly the San, have made use of the plant’s tubers for medicinal purposes for centuries. Ethno-medicinal uses have been recorded mostly for digestive disorders, fever, sores, ulcers and boils, and as an analgesic. Today, devil’s claw is widely used in rural communities, mostly as a general health tonic, an analgesic and a treatment for digestive disorders.
Although the plants were first collected and described by European scientists in 1822, the medicinal properties of devil’s claw were only ‘discovered’ in Namibia in 1907 by GH Mehnert, as a result of his access to the knowledge of the indigenous Khoi and San people. This early bio-prospector exported some dried devil’s claw tubers to Germany, where they were first studied by B. Zorn at the University of Jena in the 1950s,whereafter the medicinal value of devil’s claw for the treatment of rheumatism, arthritis and other ailments of this nature began to be recognised by ‘western medicine’. In 1962, the Namibian company Harpago (Pty) Ltd started exporting devil’s claw-tubers in larger quantities to the German company Erwin Hagen Naturheilmittel GmbH.
Devil’s claw products are registered as Herbal Medicines in France and Germany, and as Food Supplements in the United Kingdom, Netherlands, the USA and the Far East. Lending credibility to its efficacy, devil’s claw’s applications are listed in various references, amongst which the following are considered to be the most important:
- The European Pharmacopoeia. Published in 1964, sets out common standards for the composition and preparation of substances used in the manufacture of medicines, with the aim of guaranteeing their quality. The monographs listed have the force of law, replacing earlier national pharmacopoeias. It supplies manufacturers with a list of ‘reference samples’, enabling them to ascertain and ensure the quality and conformity of medicines produced and marketed in Europe, or exported from it. It is recognised as one of the main authorities on medicinal quality and safety, and its cooperation with the European Union has resulted in the setting-up of a scientific research programme to standardise biological medicines, and an official network of medicine control laboratories. This pooling of expertise helps to ensure that the same quality standards are applied throughout Europe.
- The German Commission E (the German equivalent of the Food and Drug Administration (FDA) in the United States), is a governmental regulatory agency that was established in 1978 to evaluate and approve traditional, folk and herbal medicaments and to publish monographs listing uses and side effects. Under one of these monographs, devil’s claw is indicated for the treatment of painful arthrosis, loss of appetite and dyspepsia, and as a supportive therapy for degenerative disorders of the locomotive system.
- The monographs of The European Scientific Cooperative on Phytotherapy (ESCOP), founded in June 1989, is as an umbrella organisation representing national phytotherapy associations across Europe with the aim of advancing the scientific status of phytomedicines and assisting with the harmonisation of their regulatory status at the European level. ESCOP recognises it for the treatment of painful arthrosis, tendonitis, loss of appetite and dyspepsia.
More recently, in 2004, the EU Directive on Traditional Herbal Medicinal Products 2004/24/EC came into force aimed at making the entry of traditionally used medicinal products into the EU simpler, while at the same time ensuring that quality and safety standards are met, thereby providing safe usage information and giving the public confidence in the use of these applications. A seven-year transitional phase was granted for unlicensed products on the market to become registered. A necessary requirement for registration was that the product should demonstrate at least 30 years of traditional use, of which 15 years must have been in the EU. By April 2011, all herbal medicinal products had to be registered under this directive to remain in the market. They could either be designated as ‘well established use’ or as ‘traditional use’. However, there seem to be differences in the interpretation of the above, for example, in Germany devil’s claw is approved under the ‘well established use’ category, while elsewhere it is approved under ‘traditional use’.
Clinical research has demonstrated the efficacy of devil’s claw as an analgesic, antirheumatic and antiinflammatory agent in the treatment of, for example, back pain. Its main commercial use today derives from an extract from the root tubers which is added to various proprietary joint-care products. Active ingredients that have been noted include iridoid glycosides such as harpagoside, procumbide and harpagide, phenols such as acetosid and isoacetoside, and other substances including harpagoquinones, amino acids, flavonoids and phytosterols. The relative presence of these complex molecules constitutes the main chemical difference between H. procumbens and H. zeyheri.
In general, the level of active ingredients, in particular that of harpagoside, is used to determine the quality of dried tubers supplied. Aqueous or ethanol-based technologies are most commonly used for the extraction of the active ingredients, although extraction can also be effected with liquid carbon dioxide and a cosolvent. Various patents regarding extraction technologies have been registered.
Broadly speaking there are presently three key market segments for devil’s claw:
- as an extract in herbal medicines – generally referred to as ‘traditional herbal remedies’ – sold over the counter as opposed to on prescription from a medical doctor. In Germany, the proportion of prescriptions from physicians for the treatment of poly-arthritis, and back and joint pains that included Harpagophytum had increased significantly from 40% in 2000 to 60% in 2001, accounting for approximately 74% of the treatments for rheumatism in that country. This, however, decreased when devil’s claw (and a number of other “natural products”) was removed from the list of claimable items on medical aid schemes in 2004. By mid-2004, the sales of herbal medicines in Germany (including devil’s claw) had decreased by approximately 50%.
- as a raw material for veterinary herbal remedies or animal food supplements, or an extract in a proprietary veterinary ‘cure’; and
- as a herbal tea with therapeutic qualities.
Of these traditional herbal medicines are estimated to have the biggest market share (92%), followed by veterinary medicine (5%), and then herbal tea (3%).