Radix Harpagophyti consists of the dried, tuberous, secondary roots of Harpagophytum procumbens DC. ex Meiss. (Pedaliaceae).
Harpagophytum burcherllii Decne.
Selected vernacular names
Afrikanische Teufelskralle, beesdubbeltjie, devil’s claw, duiwelsklou, grapple plant, grapple vine, harpagophytum, kanako, khams, khuripe, legatapitse, sengaparele, Teufelskralle, Trampelklette, wood spider xwate.
Prostrate perennial mat-forming herb, up to 1.5 m across.
Tuber up to 6 cm in diameter, bark yellowish-brown, longitudinally striated.
Leaves pinnately lobed and clothed with glandular hairs, the underside densely pubescent.
Flowers bright red, solitary, rising abruptly from the leaf axils; corolla pentamerous, tubular, pink-purple, up to 7 cm long; androecium of four stamens with one staminodium.
Fruits characteristically large, hooked, claw-like, tardily dehiscent two-locular capsules, fl attened at right angles to the septum, the edges bearing two rows of woody arms up to 8 cm long with recurved spines.
Irregular thick, fan-shaped or rounded slices or roughly crushed discs of tuber, 2–4 cm and sometimes up to 6 cm in diameter, 2–5 mm thick, greyish-brown to dark brown.
Darker outer surface traversed by tortuous longitudinal wrinkles.
Paler cut surface shows a dark cambial zone and xylem bundles distinctly aligned in radial rows.
Central cylinder shows fi ne concentric striations.
Seen under a lens, the cut surface presents yellow to brownish-red granules, longitudinally wrinkled; transverse surface yellowish-brown to brown, central region raised, fracture short.
Several rows of large, thin-walled cork cells frequently with yellowish-brown contents; parenchymatous cortex with very occasional sclereids with reddish-brown contents, xylem arranged in concentric rings; reticulately thickened vessels, some with rounded perforations in the end walls (tracheidal vessels); abundant lignifi ed parenchymatous cells associated with the vessels and in the small central pith.
Powdered plant material
Brownish-yellow with fragments of cork layer consisting of yellowish-brown,
thin-walled cells; fragments of cortical parenchyma consisting of large, thin-walled cells, sometimes containing reddish-brown granular inclusions and isolated yellow droplets; fragments of reticulately thickened vessels and tracheidal vessels with associated lignifi ed parenchyma from the central cylinder; small needles and crystals of calcium oxalate present in the parenchyma.
May show rectangular or polygonal pitted sclereids with dark reddish-brown contents. Parenchyma turns green when treated with a solution of phloroglucinol in hydrochloric acid.
Uses supported by clinical data
Treatment of pain associated with rheumatic conditions.
Uses described in pharmacopoeias and well established documents
Treatment of loss of appetite and dyspeptic complaints; supportive treatment of degenerative rheumatism, painful arthrosis and tendonitis .
Uses described in traditional medicine
Treatment of allergies, boils, diabetes, liver disorders and sores.
Anti-infl ammatory and analgesic activity
A 60% ethanol extract of Radix Harpagophyti, 100.0 μg/ml, standardized to contain 2.9% harpagoside, inhibited the release of tumour necrosis factor- α (TNF-α) induced by the treatment of human monocytes with lipopolysaccharide (LPS) in vitro. However, treatment of the monocytes with harpagoside and harpagide, 10.0 μg/ml, isolated from the roots, had no effect on LPS-induced TNF-α release.
Harpagoside, 10.0–100.0 μmol/ l, reduced the synthesis of thromboxane B2 in cells treated with calcium ionophore A23187.
The results of studies assessing the anti-infl ammatory activity of Radix
Harpagophyti in animal models are confl icting. Intragastric administration of 20.0 mg/kg body weight (bw) of an aqueous or methanol extract of the root to rats inhibited oedema and infl ammation in the granuloma pouch and carrageenan-induced footpad oedema tests.
Intragastric administration of 20 mg/kg bw of a methanol extract of the root inhibited erythema induced by ultraviolet light in rats.
Intragastric administration of 20.0 mg/kg bw of the same methanol extract to mice exhibited analgesic activity in the hot-plate test, but did not inhibit benzoquinoneinduced writhing.
Intraperitoneal pretreatment of rats with an aqueous extract of the roots reduced carrageenan-induced footpad oedema in a dose-dependent manner.
Doses of 400 mg/kg bw and 1200 mg/kg bw reduced oedema by 43% and 64%, respectively, 3 hours after administration.
The effi cacy of the higher dose was similar to that of indometacin, 10 mg/kg bw.
Intraperitoneal administration of 400.0 mg/kg bw of achloroform extract of the roots to mice with carrageenan-induced footpad oedema and infl ammation reduced infl ammation by 60.3% 5 hours after treatment.
Intraperitoneal administration of 200–400 mg/kg bw of an aqueous extract of the roots reduced carrageenan-induced footpad oedema in rats, but did not increase the reaction time of mice in the tail-fl ick hot-plate test.
The anti-infl ammatory activity of the highest dose was more effi cient in rats than indometacin, 10.0 mg/kg bw.
Treatment of the aqueous extract with 0.1 mol/l hydrochloric acid dramatically decreased the activity, suggesting that oral dosage forms should be enteric coated to protect the active principles from stomach acid. In the same study, harpagoside did not appear to be involved in the anti-infl ammatory activity.