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Asteranthe asterias (S.Moore) Engl. & Diels

Protologue
Engl., Monogr. afrik. Pflanzen-Fam. 6: 30, t. 8B (1901).
Family
Annonaceae
Vernacular names
Msaluti (Sw).
Origin and geographic distribution
The distribution of Asteranthe asterias is limited to coastal regions of Kenya and Tanzania.
Uses
The stems are used as building poles. In Kenya the aromatic bark and leaves are used locally for flavouring food. A paste made of pounded roots is applied to swellings.
Properties
The bark of stems and roots showed in-vitro activity against Plasmodium falciparum and Trypanosoma brucei rhodesiense, the parasites that cause malaria and sleeping sickness, respectively. Two diprenylated indoles, 2’,3’-epoxyasteranthine and 2’, 3’-dihydroxyasteranthine, were isolated from the stem bark and root bark. These compounds exhibited remarkable antifungal activity against Saprolegnia and Rhizoctonia spp., comparable with that of the standard antimycotic agent naftifine.
Botany
Evergreen shrub or small tree up to 8 m tall; bole up to 20 cm in diameter; bark surface finely striped, grey-brown to blackish; twigs with lenticels, velvety hairy. Leaves alternate, simple and entire; stipules absent; petiole 2–7 mm long; blade obovate to oblong, (1–)4–18 cm × (0.5–)2–6 cm, rounded to slightly cordate at base, acuminate at apex, papery, glabrous or hairy below, pinnately veined. Flowers 1–2 together outside the leaf axils, bisexual, regular, 3-merous, pendulous, scented; pedicel 3–8 mm long; sepals free, triangular, 0.5–1 cm long, densely hairy; petals 6, united at base, linear-oblong to linear-lanceolate, 2.5–6 cm long, finely hairy, creamy white with red-purple marking, base thickened and yellowish; stamens numerous, 1.5–2.5 mm long, with very short filaments; carpels 10–22, free, 2–2.5 mm long, densely hairy. Fruit consisting of up to 6 indehiscent follicles 2–4 cm × c. 1 cm, velvety brown hairy, slightly constricted between the seeds, each follicle 3–10-seeded. Seeds ellipsoid, 7–8 mm × 4–5 mm, yellow-brown, with ruminate endosperm.
It has been suggested that the flowers are pollinated by beetles. In Kenya fruits can be found in October–November. African civet (Civettictis civetta) may disperse the seeds.
Asteranthe comprises only 2 species. It is related to Hexalobus and Uvariastrum. Asteranthe lutea Vollesen is a shrub or small tree up to 10 m tall from eastern Tanzania. It differs from Asteranthe asterias in its large bracteoles and in its flowers having yellowish, fleshy petals with a dark red, not thickened base.
Two subspecies have been distinguished in Asteranthe asterias. Subsp. triangularis Verdc. differs from subsp. asterias in its usually smaller leaves persistently hairy below and its narrowly triangular, often slightly shorter petals; it is endemic to north-eastern Tanzania.
Ecology
Asteranthe asterias occurs in lowland evergreen forest and bushland up to 650 m altitude. It is locally common, and sometimes dominant in the shrub layer. It is commonly found along streams and on limestone soils.
Genetic resources and breeding
Although both Asteranthe species have limited distribution areas and occur in habitat types that are under much pressure by human activities, there are no signs that they are threatened yet. Exploitation for timber or medicinal purposes seems to be on a small scale only, but some monitoring of the populations is recommended.
Prospects
The use of the wood for construction of local houses will remain of limited importance. The medicinal properties of the bark deserve more attention, particularly the antimalarial, antitripanosomal and antifungal activities.
Major references
• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• Nkunya, M.H.H., Jonker, S.A., Mdee, L.K., Waibel, R. & Achenbach, H., 1996. New diprenylated indoles from Asteranthe asterias (Annonaceae). Natural Product Letters 9: 71–78.
• Verdcourt, B., 1971. Annonaceae. In: Milne-Redhead, E. & Polhill, R.M. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 131 pp.
Other references
• Couvreur, T.L.P., 2008. Revealing the secrets of African Annonaceae. Systematics, evolution and biogeography of the syncarpous genera Isolona and Monodora. PhD thesis Wageningen University, Netherlands. 296 pp.
• Engel, T.R., 2000. Seed dispersal and forest regeneration in a tropical lowland biocoenosis (Shimba Hills, Kenya). PhD thesis, Faculty of Biology, Chemistry and Geosciences, University of Bayreuth, Germany. Logos Verlag, Berlin, Germany. 345 pp.
• Freiburghaus, F., Jonker, S.A., Nkunya, M.H.H., Mwasumbi, L.B. & Brun, R., 1997. In vitro trypanocidal activity of some rare Tanzanian medicinal plants. Acta Tropica 67: 181–185.
• Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
• Vollesen, K., 1980. Notes on Annonaceae from Tanzania. Botaniska Notiser 133(1): 53–62.
Author(s)
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article:
Lemmens, R.H.M.J., 2009. Asteranthe asterias (S.Moore) Engl. & Diels. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.