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Strophanthus hispidus DC.

Protologue
Bull. Sci. Soc. Philom. Paris 3: 123, t. 8 (1802).
Family
Apocynaceae
Chromosome number
2n = 18
Vernacular names
Poison arrow vine, brown strophanthus, hairy strophanthus (En).
Origin and geographic distribution
Strophanthus hispidus occurs from Senegal east to the Central African Republic, DR Congo, Uganda and western Tanzania and south to northern Angola.
Uses
In the savanna zone of West Africa the latex and seeds of Strophanthus hispidus have been used mostly to make arrow poison; the plant has locally been cultivated for this purpose and for trade, and remnants of small plantations still exist. The seeds are usually pounded together with other poisonous plant or animal parts and the liquid evaporated to obtain a sticky mass. Because of their great toxicity, the seeds are not used in traditional medicine. Decoctions of the roots or sometimes of the pulped root bark, stem bark or leaves are used externally to treat skin diseases, leprosy and ulcers, and internally to treat parasites, malaria, dysentery and gonorrhoea. A decoction of the bark or leaf sap is taken against the effects of snakebites. In Guinea the sap from crushed leaves or young shoots is applied to kill head-lice and other parasites. A decoction of the bark is dripped into the eye to treat conjunctivitis. In Nigeria and Ghana a leaf and stem decoction is taken as a laxative or to treat fever, and is externally applied to sores. A root decoction is taken to treat rheumatic afflictions. In Togo beer with root bark macerate and potassium carbonate, sometimes mixed with other plants, is taken to treat oedema.
Nowadays, the glycosides extracted from the seeds (‘Semen strophanthi’) are used in a number of medicines in several European countries, the United States, Argentina and Chili as a rapid cardiac and vascular stimulant.
In south-western Burkina Faso the young leaves are made into a tasty sauce, which is also restorative. The stems stripped from their bark are used in Nigeria for the end pieces of reed screens, and for cotton-carding bows.
Production and international trade
Strophanthus seeds are exported to Europe and the United States. In Germany the seeds of Strophanthus hispidus are preferred because their purity can be tested easily. The British, French and Swiss officially favour Strophanthus kombe Oliv., while the United States Pharmacopoeia recognizes both.
Properties
A large number of cardiac glycosides (cardenolides) have been isolated from Strophanthus hispidus. These glycosides, collectively called strophanthins, are most abundant in the seed and are responsible for the activity in arrow poison as well as cardiac and vascular stimulant. In comparison with Digitalis cardenolides, they are characterized by highly oxygenated aglycones.
The seeds of Strophanthus hispidus contain 4–8% of a glycoside mixture, mainly with strophanthidin as aglycone: cymarin (k-strophanthin-α) and k-strophanthoside (k-strophanthin-γ). Minor components have as aglycones strophanthidol and periplogenin. Used as arrow poison, these glycosides cause the heart to arrest in systole. The sole official use of Strophanthus drugs in medicine is for their influence on the circulation, especially in cases of chronic heart weakness. As the action is similar to that of Digitalis glycosides, although more likely to cause digestive disturbances and diarrhoea, Strophanthus drugs are often useful as an alternative or adjuvant. Some believe that Strophanthus glycosides have a direct stimulating effect upon the kidney and are superior to Digitalis glycosides as a diuretic, but the evidence in favour of this view is far from convincing. While they possess some local anaesthetic powers, they are so highly irritant that it is not practical to use it for this effect.
An aqueous leaf extract showed a dose-related delay of blood clotting due to the venom of the saw-scaled viper (Echis carinatus), thus inhibiting the effect of its bite. This venom causes rapid intra-arterial clotting of blood, resulting in death in small animals, while death in larger animals and in man occurs due to depletion of fibrinogen reserves and internal haemorrhage. Extracts of Strophanthus hispidus showed significant anti-inflammatory activity against acute inflammation.
The extracts of both the roots and leaves showed in-vitro inhibition of the bacteria Escherichia coli, Klebsiella pneumoniae, Neisseria gonorrhoeae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes. Strains of the pathogens with laboratory induced resistance against certain antibiotics were also sensitive to the aqueous and ethanolic extracts of Strophanthus hispidus.
Adulterations and substitutes
The seeds of Strophanthus sarmentosus DC. are commonly used in the savanna zone of West Africa for arrow poison, but usually in regions where Strophanthus hispidus is rare or absent. In the forest regions, Strophanthus gratus (Wall. & Hook.) Franch. is preferred over Strophanthus hispidus, also because the last species grows very high into the trees, where the fruits are inaccessible. The Mongo people of DR Congo prefer the similarly highly cardiotoxic Periploca nigrescens Afzel. over Strophanthus spp., or use them together to make poison. The seeds of Strophanthus hispidus are sometimes adulterated with those of several other Strophanthus spp., e.g. Strophanthus thollonii Franch. or Strophanthus gratus.
Description
Deciduous shrub up to 5 m tall or large liana up to 100 m long, with clear, reddish or white exudate; stem up to 6 cm in diameter; bark dark grey; branches with few to many lenticels, dark brown or blackish. Leaves decussately opposite or rarely in whorls of three, simple and entire; stipules absent; petiole 1–5 mm long; blade ovate or elliptical to obovate, 3–15 cm Χ 1.5–8 cm, base rounded or slightly cordate, apex acuminate, sparsely to densely stiff-hairy. Inflorescence a terminal dichasial cyme, on long or short branches or in the forks, lax or congested, 1–70-flowered; peduncle 1–55 mm long; bracts narrowly ovate or elliptical, 0.5–3 cm long. Flowers bisexual, regular, 5-merous; pedicel 0.5–3 cm long; sepals free, unequal, ovate to linear, 13–35 mm long, acute; corolla tube 11–22 mm long, widening at 54–66% of its length into a cup-shaped upper part, at the mouth 7.5–17 mm wide, hairy on both sides except for the base, white and turning orange, suffused with red near the base, red- or purple-spotted inside, corona lobes tongue-shaped, 1–3 mm long, with rounded tip, fleshy, minutely hairy or scabrous, yellow, reddish or brown-spotted inside, corolla lobes ovate, rather abruptly narrowing into the 1 mm wide pendulous tails, lobes including tails 15–23 cm long, short hairy on both sides, creamy and turning orange on both sides, red- or brown- spotted inside, tails yellow, greenish yellow or reddish; stamens inserted at 7–13 mm from the base of the corolla tube, included; ovary half-inferior, 2-celled, style 7–12 mm long, ending in a ringlike pistil head surrounding the minute stigma. Fruit consisting of 2 ellipsoid follicles 25–50 cm Χ 1.5–2 cm, tapering into a narrow apex and ending in a large knob, 2-valved, divergent at 200–260°, wall thick and hard, grooved, hairy or glabrescent, many-seeded. Seeds spindle-shaped, 10–18 mm Χ 2–3 mm, densely pubescent, at apex with a long beak up to 8 cm long, in upper 2–4.5 cm with long hairs up to 8.5 cm long.
Other botanical information
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 hispidus is closely related to Strophanthus kombe Oliv. Strophanthus mortehanii De Wild. is chemically related to Strophanthus hispidus; it occurs from Cameroon to Gabon and northern DR Congo. In DR Congo the crushed seeds are mixed with the latex of Periploca nigrescens Afzel. and used as an arrow poison. Strophanthus parviflorus Franch. occurs in Gabon, Congo and northern DR Congo and the seeds are used in Congo to make arrow poison.
Growth and development
If pruned regularly, rooted branches will develop in a few years into a thick shrub or small tree, producing more fruits than wild plants. In Ghana Strophanthus hispidus is found flowering from February to April (rarely to July), and fruiting from January to July. In areas with distinct dry and rainy seasons, Strophanthus hispidus flowers towards the end of the dry season and the beginning of the rainy season; fruits are mature in the dry season.
Ecology
Strophanthus hispidus occurs in primary and secondary moist forest, or in woodland on rocky outcrops or in thickets, from sea-level up to 1600 m altitude.
Propagation and planting
Strophanthus hispidus can be grown from seed or rooted branches. In northern Togo, 1-m-long branches are stuck in the ground; they root quickly.
Management
Young plants of Strophanthus hispidus need careful watering. Protection from insects and other animals is necessary.
Harvesting
Fruits of Strophanthus hispidus remain closed longer than those of Strophanthus sarmentosus, and thus can be harvested later, which is an advantage as only ripe seeds have maximum activity.
Handling after harvest
For arrow-poison use, almost mature fruits are kept in a pot until they open. The seeds are then cleaned by removing the tuft of hair by stirring or burning, and they are roasted to preserve their chemical properties by destroying the enzyme, which converts the glycosides into biologically inactive compounds when the seeds are stored for a long time or become damp.
Genetic resources
Because of its wide distribution and its habitat range Strophanthus hispidus is not threatened by genetic erosion. No concerted efforts to conserve genetic resources or breeding programmes are known.
Prospects
Strophanthus hispidus is a source of compounds that are useful in treating heart failure and blood circulation disorders. The biotransformation abilities of Strophanthus plant cell and tissue cultures may provide new, more effective and safer cardiac glycosides useful in the pharmaceutical industry. Because of its easy growth and beautiful flowers, Strophanthus hispidus would make an interesting ornamental plant.
Major references
• Beentje, H.J., 1982. A monograph on Strophanthus DC. (Apocynaceae). Mededelingen Landbouwhogeschool Wageningen 82–4. Wageningen, Netherlands. 191 pp.
• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 960 pp.
• Ebana, R.U.B., Madunagu, V.E. & Etok, C.A., 1993. Antimicrobial effect of Strophanthus hispidus and Secamone afzeli on some pathogenic bacteria and their drug resistant strains. Nigerian Journal of Botany 6: 27–31.
• Hendrian, R., 2001. Strophanthus DC. In: van Valkenburg, J.L.C.H. & Bunyapraphatsara, N. (Editors). Plant Resources of South-East Asia No 12(2): Medicinal and poisonous plants 2. Backhuys Publishers, Leiden, Netherlands. pp. 519–523.
• Neuwinger, H.D., 1996. African ethnobotany: poisons and drugs. Chapman & Hall, London, United Kingdom. 941 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
Other references
• Akah, P.A. & Nwambie, A.I., 1994. Evaluation of Nigerian traditional medicines 1: plants used for rheumatic (inflammatory) disorders. Journal of Ethnopharmacology 42(3): 179–182.
• Burkill, H.M., 2000. The useful plants of West Tropical Africa. 2nd Edition. Volume 5, Families S–Z, Addenda. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 686 pp.
• Githens, T.S., 1948. Drug plants of Africa. African Handbooks: 8. University of Pennsylvania Press, Lancaster Press, Lancaster, United States. 125 pp.
• Houghton, P.J. & Skari, K.P., 1994. The effect on blood clotting of some West African plants used against snakebite. Journal of Ethnopharmacology 44(2): 99–108.
Sources of illustration
• Beentje, H.J., 1982. A monograph on Strophanthus DC. (Apocynaceae). Mededelingen Landbouwhogeschool Wageningen 82–4. Wageningen, Netherlands. 191 pp.
Author(s)
• H.J. Beentje
Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, United Kingdom


Editors
• G.H. Schmelzer
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
• A. Gurib-Fakim
Faculty of Science, University of Mauritius, Rιduit, Mauritius
Associate editors
• C.H. Bosch
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
• M.S.J. Simmonds
Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, United Kingdom
• R. Arroo
Leicester School of Pharmacy, Natural Products Research, De Montfort University, The Gateway, Leicester LE1 9BH, United Kingdom
• A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
• R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
• L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Photo editor
• A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Beentje, H.J., 2006. Strophanthus hispidus DC. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes mιdicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map wild


1, flowering branch; 2, follicle with middle section removed; 3, seed.
Redrawn and adapted by Iskak Syamsudin



flowering branches


inflorescence