Prota 11(1): Medicinal plants/Plantes mιdicinales 1
Bull. Misc. Inform. Kew 1894: 24 (1894).
2n = 22
Conopharyngia elegans (Stapf) Stapf (1902).
Toad tree, low-veld toad tree (En). Mkuti, mbombo (Sw).
Origin and geographic distribution
Tabernaemontana elegans occurs in East Africa and southeastern Africa, from Somalia south to South Africa and Swaziland.
The seeds, stem bark and roots of Tabernaemontana elegans are used by the Wabondei and Wadigo people of Tanzania for treating heart diseases. The powdered root bark or fruits are used to treat cancer. In southern Africa the coagulated latex or pulverized root mixed with vaseline is applied as a styptic. A root decoction is applied as a wash for wounds and is taken as a remedy for pulmonary diseases and chest pains. A maceration of root ash is drunk to treat tuberculosis and stomach-ache. A root maceration acts as a purgative. Burnt root powder mixed with salt and water is used as a vaginal wash to treat menorrhagia, infertility and venereal diseases. In Zimbabwe a root decoction is taken as an aphrodisiac.
The wood is white and easy to work. It is used for firewood, and for making spoons, knife and sword handles, bows and arrows, building poles and pegs for animal traps. The latex is tapped for making birdlime or used as a glue for arrow heads. In Zimbabwe and Mozambique, the orange, slimy fruit pulp is relished by some people. Zulu people put the fruit into milk they wish to curdle fast. Tabernaemontana elegans is an unusual, but attractive garden tree with its sweet-smelling flowers and unusual fruits covered in brown warts, giving it the look of a toads skin.
The phytochemically important compounds of Tabernaemontana elegans root bark are the monomeric indole alkaloids dregamine and tabernaemontanine (corynanthean class), and the bisindole alkaloids conoduramine and tabernaelegantines (corynanthean-ibogan class). The tabernaelegantines are rare in other Tabernaemontana species, and are thus reliable chemotaxonomic markers for Tabernaemontana elegans. The main components of the aerial parts are dregamine, tabernaemontanine and vobasine (corynanthean class), followed by apparicine (pericalline, aspidospermatan class), and tabernaelegantine A and B. Minor components are dregaminol, tabernaemontanine (corynanthean class), tabernaemontaninol (vobasan), 3-hydroxyconodurine and tabernaelegantine C and D. The alkaloid content of callus cultures is similar to that of the whole plant, but the tabernaelegantines are absent. The main alkaloid in callus cultures is apparicine, followed by vobasine and tabernaemontanine. Minor components include 3-hydroxycoronaridine (ibogan class) and 3-hydroxyconodurine. 3-Hydroxyconodurine, 3-hydroxycoronaridine, conoduramine and apparicine show strong inhibitory activity against a range of gram-positive and gram-negative bacteria. Dregamine shows convulsant and respiration-stimulant activities. It also inhibits muscular fatigue in vitro and in vivo comparable to ibogaine from Tabernanthe iboga Baill. It has been used in treatments of muscular and nervous asthenia, respiratory depression and type III poliovirus (HPV-3). Apparicine has also shown strong activity against type III poliovirus, as well as significant cytotoxicity against P-388 lymphocytic leukaemia cell cultures. Apparicine has shown opioid activity in opiate receptor studies. Tabernaemontanine has a vasodilatory effect and can be used in humans in cases of arteriosclerosis, cerebral trauma and circular irregularities. It shows antibacterial activity against several human pathogenic bacterial strains, and is cytotoxic to human nasopharyngeal epidermoid carcinoma cells in vitro, but is inactive against P-388 lymphocytic leukaemia in mice. Vobasine exhibited little activity in general pharmacological screening tests.
Shrub or small tree up to 15 m tall, repeatedly dichotomously branched, trunk up to 30 cm in diameter, bark longitudinally fissured, corky. Leaves opposite, simple and entire; ocrea widened into stipules in axils of petioles; petiole 730 mm long; blade elliptical or narrowly elliptical, 623 cm Χ 28 cm, base cuneate or decurrent into the petiole, apex acuminate, acute or obtuse. Inflorescence a corymb 520 cm long, 2 together in the forks of the branches, many-flowered; peduncle 18.5 cm long, lax. Flowers bisexual, regular, 5-merous, sweet-scented; pedicel 26 mm long; sepals orbicular to broadly ovate, 12.5 mm long; corolla tube almost cylindrical, 57 mm long, lobes obliquely elliptical, slightly falcate, 815 mm long, entire, spreading, white, creamy or pale yellow; stamens inserted 22.5 mm above the corolla base, included, anthers sessile, narrowly triangular; ovary superior, almost globose, consisting of 2 free carpels, styles fused, slender, straight, pistil head composed of 2 rings, the upper one grading into the slender stigmoid apex. Fruit composed of 2 separate, obliquely ovoid or ellipsoid follicles 58 cm long, glaucous or green, with conspicuous brown warts, with 3 ridges, dehiscent, many-seeded. Seeds obliquely ellipsoid, 1415 mm long, with reticulate grooves, papillose, dark brown, aril orange. Seedling with epigeal germination; cotyledons almost orbicular, c. 6 mm long, base cordate, apex obtuse.
Tabernaemontana comprises about 110 species and is pantropical. About 18 species occur in mainland Africa and 15 in Madagascar.
Tabernaemontana elegans flowers in Kenya from October to May, in Mozambique from April to September, and fruits there from July to October. In South Africa it flowers from September to March with a peak in November, and fruits from February to August.
Tabernaemontana elegans occurs in bushland, forest on coastal dunes, gallery forest or woodland, usually associated with Brachystegia spp., up to 1000 m altitude. It is semi-frost resistant and can grow in full sun to half-shade. It requires a moderate amount of water. Because of its corky bark, it is fairly fire resistant.
Genetic resources and breeding
Tabernaemontana elegans is relatively widespread in eastern Africa and does not seem to be at risk of genetic erosion.
Tabernaemontana elegans contains many pharmacologically interesting indole alkaloids and deserves more attention from research.
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Correct citation of this article:
Schmelzer, G.H., 2006. Tabernaemontana elegans Stapf. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes mιdicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
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