Prota 11(1): Medicinal plants/Plantes médicinales 1
Journ. Bot. 58: 271 (1920).
Euphorbiaceae (APG: Putranjivaceae)
Drypetes amoracia Pax & K.Hoffm. (1922).
Horseradish tree, okhuaba, akot (En). Bossmé, yungu, youngou (Fr).
Origin and geographic distribution
Drypetes gossweileri occurs from Nigeria east to the Central African Republic and south to DR Congo.
The bark has a pungent taste, and has many medicinal uses. A bark decoction or maceration is widely drunk as a purgative to expel intestinal worms and treat diarrhoea; it is also applied as an enema. The ground stem bark mixed with palm oil is rubbed in to treat headache, toothache, intercostal pain, kidney pain, rheumatism and bronchitis.
In Cameroon and Congo stem bark powder is eaten to treat sexual asthenia and to treat venereal diseases. In Congo the bark powder cooked with banana is taken as an aphrodisiac. In the Central African Republic a bark decoction is drunk as a tonic after childbirth, and to treat bronchitis, cough and other lung problems. A bark decoction is rubbed onto scabies and is also used for bathing children to treat fever. A paste of stem bark scrapings in water is applied to injuries, ulcers and swellings. In DR Congo a leaf decoction is used as a wash and is drunk as a treatment for asthma in children. The bark powder is taken by women to induce abortion.
The stem bark, leaves and fruits are used to stupefy fish to catch them more easily. In Cameroon the cooked seeds are eaten by the Baka pygmies. The wood is used for planks and carpentry, but the sawdust can cause dermatitis, ocular and respiratory problems. In Gabon the fruit husks are used in ritual dances, attached to the limbs and clothing. In Congo the strong-smelling roots are placed on the roof or a root decoction is sprinkled around the house to repel snakes.
Production and international trade
Drypetes gossweileri is only traded locally as a medicinal plant. The dried stem bark is sold in the local markets of Cameroon for the treatment of typhoid diarrhoea; in 2002 the bark was sold at about US$ 0.20 per g.
All parts of the tree when bruised or cut emit a pungent smell, resembling that of horseradish or mustard. The essential oil of the stem bark obtained from samples from the Central African Republic and Gabon contained mainly benzyl isothiocyanate (56–94%), accompanied by benzyl cyanide and benzaldehyde. The main component in a sample from Cameroon was benzyl cyanide (19.4–73.7%). Minor compounds are the triterpenes friedelin, friedelane-3,7-dione and derivatives, methyl putranjate, stearic acid, stigmasterol stearate and β-sitosterol stearate. The bark also contains the alkaloid drypetesgenine and the podocarpane diterpenoid gossweilone.
Crude aqueous and ethanol extracts of the stem bark inhibited the growth of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella sp. and Proteus sp., with the ethanol extracts exhibiting the highest inhibitory activity. The acetone extract of the stem bark showed a strong purgative effect in mice. The LD50 of the methanol stem bark extract in the brine shrimp test was low. The extract showed significant phytotoxic activity against Lemna minor L. as well as antifungal activity against Microsporum canis and Trichophyton longiformis. The antioxidant and antiradical activities of the essential oil were found to be low.
The wood is pale yellow or whitish with fine texture and moderately heavy, with a density of 760–800 kg/m³ at 12% moisture content. It is moderately hard, elastic and often has a bad smell.
Adulterations and substitutes
The pungent smell and medicinal uses of the stem bark of Drypetes gossweileri are similar to those of the roots of Pentadiplandra brazzeana Baill. And the two species are often used indiscriminately.
Medium-sized dioecious tree up to 30(–42) m tall; bole straight, up to 120 cm in diameter, often irregularly fluted; bark greyish green to yellowish green, with many lenticels, strong-smelling when cut. Leaves alternate, simple; stipules small; petiole up to 2 cm long; blade oblong, 10–24 cm × 3–9 cm, base cuneate to rounded, asymmetrical, apex acuminate, margins toothed or sometimes entire, leathery, glabrous. Inflorescence an axillary fascicle, female one few-flowered. Flowers unisexual, regular; pedicel up to 2 cm long; sepals 5, ovate, 12–16 mm long, densely short-hairy, brownish green; petals absent; male flowers with c. 30 stamens, disk cup-shaped; female flowers with superior ovary, short-hairy, styles 2. Fruit an apple-shaped drupe 8–10 cm × 5–6 cm, greenish brown or yellow, velvety brown-hairy, pulp yellow, 3– 7-seeded. Seeds compressed ovoid, pale brown.
Other botanical information
Drypetes comprises about 210 species and is distributed throughout the tropics and subtropics. About 60 species occur in continental Africa and about 15 in the Indian Ocean islands. Several other Drypetes spp. are medicinally used in Central Africa. Drypetes capillipes (Pax) Pax & K.Hoffm. occurs throughout Central Africa. In Cameroon pulverized root bark is applied to furuncles to ripen them. In Congo a bark decoction is used as a mouthwash to treat toothache and as a wash to treat kidney pain. The neck is massaged with the leaves to treat a stiff neck. Drypetes klainei Pierre ex Pax occurs in Côte d’Ivoire and Gabon, and in Gabon a maceration or decoction of fresh stem bark is rubbed in to treat rheumatism. An extract of the stem bark together with dried unripe fruits of hot pepper is drunk to expel worms. A decoction of the stem bark and leaves of Drypetes natalensis (Harv.) Hutch., occurring in eastern and southern Africa, is taken to reduce fever in patients with malaria. The wood is used for firewood, charcoal, wooden spoons, tool handles and beds.
Growth and development
Drypetes gossweileri flowers from May to December and fruits mainly in June. In Cameroon it was found that it forms an association with vesicular-arbuscular mycorrhizae (VAM).
Drypetes gossweileri occurs in semi-deciduous humid forest, including secondary forest, at low altitudes.
Handling after harvest
The harvested stem bark is used fresh or can be dried for later use.
There are no signs that Drypetes gossweileri is threatened by genetic erosion.
Drypetes gossweileri does not seem to be of particular interest to researchers, which is possibly due to the cyanide-containing compounds in the stem bark. The stem bark is expected to remain important in traditional medicine though.
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Correct citation of this article:
Tchinda, A.T. & Sob, V.S.T., 2008. Drypetes gossweileri S.Moore. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
fruit and seed