Prota 11(1): Medicinal plants/Plantes mιdicinales 1
Bot. Jahrb. Syst. 15: 376 (1892).
Strophanthus intermedius Pax (1892).
Origin and geographic distribution
Strophanthus amboensis occurs from western DR Congo to Angola and Namibia.
In Angola a decoction of the roots or leaves of Strophanthus amboensis is taken against rheumatism. The Luvale people use an enema of the root to treat venereal diseases. The Luchazi people mix the pounded root with oil and apply the ointment to treat scabies. In Namibia the seeds are used in the preparation of arrow poison.
From the seeds about 10 cardiac glycosides (cardenolides) have been isolated of which the most important are based on the aglycone sarverogenin: mainly intermedioside and panstroside, and traces of amboside, leptoside, kwangoside and sarveroside. These glycosides are highly toxic. The aglycones sarverogenin and sarmentogenin have also been isolated. Sarverogenin has also been isolated from the root and bark after hydrolysis. Leptoside has a weak cardio-stimulant action.
Cell suspension cultures from the leaves, to which digitoxigenin was added, produced 6 transformation products, e.g. periplogenin.
Deciduous shrub up to 4 m tall or liana up to 20 m long, with clear or white exudate, all parts glabrous to hairy; stem up to 20 cm in diameter; bark pale grey; branches with few to many lenticels, pale brown or purple brown. Leaves decussately opposite, simple and entire; stipules absent; petiole 29 mm long; blade ovate to broadly ovate, 212.5 cm Χ 16.5 cm, base cuneate, rounded to slightly cordate, apex rounded or acuminate, papery or thinly leathery, with translucent dots. Inflorescence a terminal dichasial cyme, on long or short branches or in the forks, lax or congested, 112-flowered; peduncle 01 cm long; bracts ovate, narrowly ovate or narrowly triangular, 26 mm long, deciduous. Flowers bisexual, regular, 5-merous; pedicel 0.52 cm long; sepals free, slightly unequal, ovate or obovate, 311 mm long, obtuse or acute; corolla tube 1527 mm long, widening at 1535% of its length into a cylindrical upper part, at the mouth 613 mm wide, short-hairy, orange-yellow turning purple via dark red, white-streaked inside, corona lobes tongue-shaped, 2.57.5 mm long, obtuse, fleshy, minutely hairy, pink or violet, corolla lobes ovate, gradually narrowing into a narrow, spreading tail, lobes including the tail 2575 mm long, hairy, reddish violet on the right outer side and whitish yellow on the left outer side, yellow on the inner side; stamens inserted at 57.5 mm from the base of the corolla tube, included; ovary half-inferior, 2-celled, style 57.5 mm long, ending in a ringlike pistil head surrounding the stigma. Fruit consisting of 2 ellipsoid follicles 1227 cm Χ 1.52.5 cm, tapering into a broad and obtuse apex, 2-valved, divergent at 180270°, wall thick and hard, many-seeded. Seeds spindle-shaped, slightly flattened, 816 mm Χ 24.5 mm, densely pubescent, at apex with a long beak up to 10 cm long, glabrous in lower half, upper half with long hairs up to 7 cm long.
Strophanthus comprises 38 species, of which 30 occur in continental Africa, 1 in Madagascar and 7 in Asia, from India to South-East Asia. Strophanthus amboensis is a variable species. It flowers towards the end of the dry and the beginning of the rainy season; flowers appear before or with the leaves. Fruits mature at the beginning of the dry season.
Strophanthus amboensis occurs in forest margins, woodland and thorn scrub, often in rock fissures, at 4502000 m altitude.
Genetic resources and breeding
Strophanthus amboensis is rather widespread and not in danger of genetic erosion.
Medicinal use of Strophanthus amboensis will be limited to local use in its area of distribution, unless further studies on the chemical constituents reveal new possibilities. Strophanthus amboensis has unusual and beautiful flowers, which makes it an interesting ornamental plant.
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Correct citation of this article:
de Ruijter, A., 2006. Strophanthus amboensis (Schinz) Engl. & Pax. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes mιdicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.