Scientific name : Harpagophytum procumbens DeCandolle

Common name : Devils' claw, grapple plant

Botany

Devil's claw grows naturally in the Kalahari desert and Namibian steppes of southwest Africa. The secondary roots are used in decoctions and teas.

History

Devil's claw has been used by native Africans as a folk remedy for diseases ranging from liver and kidney disorders to allergies, headaches and, most commonly, rheumatisms. This drug, however, is more widely used in South Africa, expecially by Bushmen, Hottentots and Bantu. Devil's claw is marketed in Canada and Europe as a home remedy for the relief of arthritic disease.

Chemistry

The major chemical component, which has been thought to be responsible for the anti-inflammatory activity of devil's claw, is harpagoside, a monoterpenic glucoside. Harpagide has also been shown to be one of the active principles of devil's claw. Harpagoside is found primarily in the roots; secondary tubers contain twice as much glucoside as the primary roots. Flowers, stems and ripe fruits are essentially devoid of the compound while traces have been isolated from the leaves. Harpagoside can be progressively hydrolyzed to harpagid and harpagogenin.5 Commercial sources of devil's claw extract contain 1.4% to 2% harpagoside.

The plant also contains procombide, a diasterio-isomer of antirrhinoside7,8 and a variety of other glycosides, the pharmacologic significance of which is unknown.

Pharmacology

Studies of the crude methanolic extract of the secondary roots of Harpagophytum procumbens indicate that its effect on smooth muscles is due to a complex interaction of the different active principles of the drug at the cholinergic receptors? The dried crude methanolic extract, harpagoside, causes significant dosedependent reduction in blood pressure, decreased heart rate and anti-arrhythmic activity on isolated rabbit heart and on intact rats.1O The extract has shown that harpagoside interferes with the mechanisms that regulate the influx of calcium in cells of smooth muscles? The methanolic extract also causes a mild decrease in the heart rate with a concomitant and positive inotropic effect at higher doses. The coronary flow decreases at higher doses only.

The negative chronotropic and positive inotropic effects of harpagoside are comparatively higher with respect to that of the extract, whereas harpagide has only \ chronotropic effect and a considerable ne one.11 In experiments on intact rats and or heart, the H. procumbens extract has d protective action with regard to arrhythmi aconitine, and particularly to those provok chloride and epinephrine chloroform.

Aqueous extract of H. procumbens signific the carrageenan-induced edema at 400 an hours after carrageenan injection. Orally extracts are inefficient, which could be aUI time in transition in the stomach, where the causing a decrease in activity of the extract The results of a German clinical study indicat claw has anti-inflammatory activity comparal phenylbutazone. Analgesia was observed, c reduction in abnormally high lJric acid and levels.

The suggestion that devil's claw possesses abortive properties has been largely disprove,

Interactions

For potential interactions, I "Potential Herb-Drug Interactions" appendix.

Toxicology

Harpagoside has been founG low toxicity with an LD 50 of greater than 13.5 g/k Although no chronic toxicity studies have been rats given oral doses of 7.5 g/kg/day harpagosidl no clinical, hematologic or gross pathologic Adverse effects in human trials have been rare, ! consisting of headache, tinnitus or anorexia.

Summary

Devil's claw extracts contain harp and harpagide which possess anti-inflammatory the ability to reduce blood pressure, decrease and slow anti-arrhythmic activities in animal: These extracts appear to be free of significant tc when given for short periods of time to animo humans; little is known about their long-term tax potential for interactions with other commonly use inflammatory agents. Additional human clinical need to be conducted before the true efficacy of claw can be stated.