Prota 11(1): Medicinal plants/Plantes médicinales 1
Bull. Jard. Bot. Etat 31: 180 (1961).
Origin and geographic distribution
Microdesmis keayana occurs from Senegal east to south-western Nigeria.
The stem bark, leaves and roots have numerous medicinal uses throughout the distribution area of Microdesmis keayana; they are similar to the uses of the closely related species Microdesmis puberula Hook.f. ex Planch. Leaf sap or crushed and burnt twigs or roots are applied to snakebites or to wounds to stop bleeding and to heal them. Leaf sap, sometimes together with twig sap, is commonly taken orally or applied as an enema to treat diarrhoea.
In Sierra Leone a paste made from pounded leaves together with those of Desmodium adscendens (Sw.) DC. is mixed with white clay and applied to scabies. The leaves, cooked with chicken, are given to treat palpitations. In Liberia a leaf infusion is taken to induce menstruation and as an abortifacient. In Côte d’Ivoire crushed leaves together with those of Mareya micrantha (Benth.) Müll.Arg. are used as a local massage to treat general body pain, painful kidneys or ribs, or overall fatigue. The Gouro people use the leafy twigs as a major component of a medicinal wash used for the daily care of newborn babies in order to prevent dermatological and intestinal affections and excessive weight loss. Ground leaves, sometimes with Capsicum fruits, or a leaf decoction are rubbed on the abdomen or taken orally to treat colic, chest complaints, fatigue, pain in the side, kidney pain and feverish stiffness. A decoction made from the leaves or leafy twigs or ground young leaves is used as a steam bath or wash to treat rheumatism or migraine. The leaf sap is applied as nose drops to treat epilepsy and convulsions. A decoction of the whole plant is taken as an emmenagogue and to treat dysentery. In Côte d’Ivoire and Ghana ground twig bark is rubbed on the body and a macerate of leafy twigs and roots is applied in the form of an enema as an aphrodisiac. A root infusion or decoction of the whole plant taken orally is also considered to be an aphrodisiac. The leaves are an ingredient of poison antidotes. In Ghana a root decoction is drunk to treat venereal diseases. Leaf and bark pulp are applied to sprains and burns. Boiled fruits are applied to tumours. The fruit is chewed to prevent ulcers. Root bark scrapings with leaves of Piper guineense Schumach. & Thonn. in water are applied to the breasts to treat mastitis. In Togo mental disorders are treated with a decoction of leaves and roots of Microdesmis keayana and Newbouldia laevis Seem. ex Bureau orally and by bathing. In Sierra Leone the leaves are one of the ingredients of an embrocation used to heal bone fractures in cattle.
The stems are used to make fishing gear and spring traps because of their strength and resilience, and the wood to make handles and implements. The plant is commonly browsed by goats and cattle. In Ghana and Nigeria the twigs are used as chew sticks. The thin flexible branches are used as ties for fastening roof thatch. In Côte d’Ivoire coastal villages grow Microdesmis keayana as a shade tree and for making village palisades. The fruits are sometimes eaten in Sierra Leone.
Three trihydroxycinnamoylspermidines were isolated from a methanolic root extract of Microdesmis keayana (collected near Abidjan, Côte d’Ivoire) and were named keayanidines A, B and C. Two other compounds were isolated from a hydromethanolic root extract: xanthoquininamide (6-hydroxyquinoline-4-carboxamide) and keayanine, a spermine derivative.
The aqueous and methanolic root extracts have hypotensive and vasorelaxing properties in tests when using normotensive rabbits in vivo and aorta strips of guinea pigs in vitro, respectively. Both extracts also showed strong anti-oxidant activity. A dichloromethane extract from the leaves showed significant antiplasmodial activity in vitro against a chloroquine-resistant strain of Plasmodium falciparum. Different plant extracts did not show significant antitrypanosomal or anthelmintic activities in vitro.
The wood is brown, hard, flexible, of fine structure and is easily worked, taking a lustrous polish.
Dioecious shrub up to 3(–6) m tall; twigs densely short-hairy. Leaves alternate, distichous, simple; stipules linear, persistent; petiole 4–12 mm long; blade elliptical-oblong to ovate-lanceolate or ovate, 5–12(–18) cm × 2–5(–7) cm, base asymmetrical, cuneate to rounded, apex acute to acuminate, margin finely toothed, shiny above, short-hairy on the midrib above. Inflorescence an axillary fascicle, male fascicle 5–many-flowered, female fascicle 1–3(–5)-flowered; bracts minute. Flowers unisexual, 5-merous, regular; calyx c. 2 mm long, lobes ovate, c. 1.5 mm long, short-hairy, green; petals almost circular to ovate-oblong, c. 3 mm × 2–2.5 mm, spreading, short-hairy in upper half, pink to orange; male flowers with pedicel 3–4 mm long, filaments c. 1 mm long, fleshy, fused to the pistillode, reddish orange, pistillode 2–2.5 mm long, reddish orange; female flower with pedicel 3–4 mm long, enlarging to 5–10 mm in fruit, short-hairy, ovary superior, ellipsoid, c. 1 mm long, (2–)3-celled, densely short-hairy, styles 2–3, c. 1 mm long, white. Fruit an ovoid drupe 4.5–6 mm × 5–8 mm, smooth when fresh, later wrinkled, hard, shiny, red, (1–)2–3-seeded. Seeds broadly ovate, flattened, curved. Seedling with epigeal germination.
Microdesmis comprises about 11 species, 2 of which occur in Asia and the others in tropical Africa. Microdesmis keayana and Microdesmis puberula are morphologically nearly similar, their medicinal uses are largely overlapping and they might well belong to the same species. The distribution area of Microdesmis puberula links up with that of Microdesmis keayana, from Nigeria east to Central Africa and Uganda.
Microdesmis keayana is common in the undergrowth of damp secondary forest, and also occurs on firm soil in primary rainforest. It is tolerant to bush fire.
Genetic resources and breeding
Microdesmis keayana is a common undergrowth species, and therefore not at risk of genetic erosion.
Several spermidine derivatives have been isolated from Microdesmis keayana; they deserve further pharmacological analysis. As Microdesmis keayana and Microdesmis puberula resemble each other morphologically and in their medicinal uses, taxonomical studies are warranted.
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Correct citation of this article:
Alvarez Cruz, N.S., 2008. Microdesmis keayana J.Léonard. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.