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Okoubaka aubrevillei Pellegr. & Normand

Protologue
Bull. Soc. Bot. France 93: 139 (1946).
Family
Santalaceae
Origin and geographic distribution
Okoubaka aubrevillei occurs from Sierra Leone east to Cameroon and DR Congo.
Uses
In West Africa Okoubaka aubrevillei bark is widely used as a medicine. Skin problems, including those caused by syphilis and leprosy, are treated by washing with, or bathing in a macerate or infusion of the bark in water. External application of bark preparations is also practised to counteract poisoning. Bark macerate is drunk to cure tachycardia and is taken as a vapour bath or as nose drops to cure oedema. In a compress it is used to disperse haematomas.
In the Western world the bark is used in phytotherapeutic medicine. Its main applications are for stomach upsets caused by poisoning and to boost the system in cases of tiredness, depression and allergies. The bark is used as a fish poison. In southern Nigeria Okoubaka aubrevillei is an important tree in religious ceremonies.
The wood is sometimes used for construction or as firewood.
Production and international trade
The bark of Okoubaka aubrevillei is traded throughout the coastal countries of West Africa. In local markets it was sold in 2005 for about US$ 20 per kg. In view of the widespread use in the Western world, international trade must be considerable, but statistics are lacking.
Properties
From the bark, 6 different catechins have been isolated, including (+)-catechin and (+)-gallocatechin, as well as β-sitosterol and stigmasterol. The bark has antimicrobial and immunostimulating properties that are attributed to phenolic compounds.
Description
Monoecious, deciduous, medium-sized tree up to 30 m tall; bole cylindrical, straight, up to 80 cm in diameter; bark surface coarse, greyish brown to reddish brown; branches horizontal, branchlets slightly grooved, densely hairy. Leaves alternate to almost opposite, simple and entire; stipules absent; petiole 3–15 mm long, 2-ribbed; blade ovate to oblong, 7.5–15 cm × 3.5–6 cm, base rounded to slightly cordate, apex acuminate, dark green, with 3–5 pairs of lateral veins, densely hairy when young. Inflorescence a panicle on older branches, up to 20 cm long. Flowers unisexual, 5-merous, regular, sessile, green; male flowers with triangular petals, c. 2.5 mm × 2.5 mm, short-hairy, stamens c. 0.5 mm long, disk cup-shaped, lobed, ovary with abortive ovules, style c. 1 mm long, stigma 4-pointed; female flowers slightly larger than male flowers, stamens sterile, disk cup-shaped, prominently lobed, hairy on upper margin, ovary superior, 4-celled, style c. 1 mm long, stigma 4-lobed. Fruit an ellipsoid drupe up to 9 cm long, glabrous, green turning yellow, 1-seeded. Seed ellipsoid, c. 7 cm × 4.5 cm, longitudinally ridged. Seedling with hypogeal germination.
Other botanical information
Okoubaka comprises 2 species and is restricted to tropical Africa. It is now generally accepted that it belongs to Santalaceae, but it was formerly placed in the families Octoknemaceae and Olacaceae. Two varieties are distinguished in Okoubaka aubrevillei: var. aubrevillei and var. glabrescentifolia J.Léonard, the latter known from DR Congo, where it is rare. Okoubaka michelsonii J.Léonard & Troupin also occurs in DR Congo and is poorly known. It is distinguished from Okoubaka aubrevillei by its glabrous branchlets and disk, shorter inflorescence and smaller fruits. The bark is taken as a febrifuge and tonic.
Growth and development
Okoubaka aubrevillei is a hemi-parasite. Within 6 months after germination, when nutrient reserves in the seed become depleted, the roots attach themselves to those of nearby plants by means of haustoria. However, one year after germination no differences were found in growth and foliar nutrient concentrations between plants grown with and without hosts. The hosts, however, showed increased mortality or reduced growth. Hence, the apparent benefit which Okoubaka aubrevillei gains from the parasitic association is killing potential competitors for water, light and nutrients. The only tree species surviving close to Okoubaka aubrevillei are Myrianthus arboreus P.Beauv. and Musanga cecropioides R.Br. Tree development is in accordance with Mangenot’s architectural model: the trunk is formed by superposition of renewal shoots from lateral buds; the new shoot is initially orthotropic but later becomes plagiotropic; the phyllotaxy is spiral in the orthotropic parts, distichous in the plagiotropic parts. This architecture is often found in climbing forest species, but is extremely rare in tree species.
Ecology
Okoubaka aubrevillei is usually found in forest on rocky hills. It is usually solitary but there are reports from Côte d’Ivoire and Ghana that it is found in pure stands.
Propagation and planting
Multiplication of Okoubaka aubrevillei is best done by seed. Germination rates of 60–100% have been recorded. Natural regeneration is poor as fruits and seeds are eaten by porcupines.
Management
In DR Congo attempts have been made to cultivate Okoubaka aubrevillei. After germination, seedlings were transplanted in rows 4 m apart, at a distance of 2 m within the row. Between the rows Millettia laurentii De Wild. was planted. After about 10 years 54% of the plants had survived and had reached an average height of 4.2 m and a maximum height of 8.6 m. Millettia laurentii did perform well for the first 6 years, but then started dying.
Harvesting
In Nigeria special rituals are performed before the bark of Okoubaka aubrevillei is removed. A wooden tool is traditionally used for the removal of the bark and under no circumstances is a metal implement used.
Genetic resources
Okoubaka aubrevillei is considered vulnerable. It is apparently rare throughout its range and the high demand for bark justifies close monitoring of its exploitation. Its poor natural regeneration is a further reason for concern.
Prospects
Study of the genetic diversity and the population biology of Okoubaka aubrevillei could form the basis for measures to protect natural stands and appropriate management. Assessment of the extent of damage done to the tree by harvesting the bark is needed to be able to specify the need for management strategies and conservation measures.
Major references
• 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.
• Cunningham, A.B., 1993. African medicinal plants: setting priorities at the interface between conservation and primary healthcare. UNESCO People and Plants Working Paper 1, Paris, France. 53 pp.
• Hawthorne, W. & Jongkind, C., 2006. Woody plants of western African forests: a guide to the forest trees, shrubs and lianes from Senegal to Ghana. Kew Publishing, Royal Botanic Gardens, Kew, United Kingdom. 1023 pp.
• Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by R.W.J. Keay, C.F.A. Onochie and D.P. Stanfield. Clarendon Press, Oxford, United Kingdom. 476 pp.
• Léonard, J., 1947. Notulae systematicae I. (Moraceae, Opiliaceae, Olacaceae, Octoknemaceae que africanae). Bulletin du Jardin Botanique de l’Etat (Bruxelles) 18: 145–153.
• Veenendaal, E.M., Abebrese, I.K., Walsh, M.F. & Swaine, M.D., 1996. Root hemiparasitism in a West African rainforest tree Okoubaka aubrevillei (Santalaceae). New Phytologist 134(3): 487–493.
• Villiers, J.-F., 1973. Octoknemaceae. Flore du Cameroun. Volume 15. Muséum National d’Histoire Naturelle, Paris, France. pp. 181–192.
• Wagner, H., Kreutzkamp, B. & Jurcic, K., 1985. Inhaltsstoffe und Pharmakologie der Okoubaka aubrevillei-Rinde. Planta Medica 51: 404–407.
Other references
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome premier. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 369 pp.
• Bouquet, A. & Debray, M., 1974. Plantes médicinales de la Côte d’Ivoire. Travaux et Documents No 32. ORSTOM, Paris, France. 231 pp.
• FAO, 1986. Some medicinal forest plants of Africa and Latin America. FAO Forestry Paper 67. Rome, Italy. 252 pp.
• Hallé, N., 1987. Okoubaka Pellegrin & Normand is really a genus of Santalaceae. Bulletin du Muséum National d’Histoire Naturelle, 4e série. Section B, Adansonia, 4: 355–363.
• Hallé, F., Oldeman, R.A.A. & Tomlinson, P.B., 1978. Tropical trees and forests: an architectural analysis. Springer Verlag, Berlin, Germany. 441 pp.
• Kerharo, J. & Bouquet, A., 1950. Plantes médicinales et toxiques de la Côte d’Ivoire - Haute-Volta. Vigot Frères, Paris, France. 291 pp.
• Léonard, J. & Troupin, G., 1950. Observations sur le genre Okoubaka Pellegr. & Normand (Octoknemaceae). Bulletin du Jardin Botanique de l’Etat (Bruxelles) 20: 11–14.
• Louis, J. & Léonard, J., 1948. Octoknemaceae. In: Robyns, W., Staner, P., De Wildeman, E., Germain, R., Gilbert, G., Hauman, L., Homès, M., Lebrun, J., Louis, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 1. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 288–293.
• Maundu, P., Kariuki, P. & Eyog-Matig, O., 2004. Threats to medicinal plant species: an African perspective. In: Proceedings of the 3rd IUCN World Conservation Congress, held in Bangkok Thailand, 17–25 November 2004. [Internet] http://www.iucn.org. Accessed December 2007.
• NACGRAB, 2004. Preliminary investigations into vegetative multiplication of some forest trees of phytomedicinal importance in South-West Nigeria. In: Annual Report of the National Centre for Genetic Resources and Biotechnology, Ibadan, Nigeria. 85 pp.
• Normand, D., 1950. Atlas des bois de la Côte d’Ivoire. Tome 1. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 148 pp.
• Razali Yusuf, 1999. Santalum album L. In: Oyen, L.P.A. & Dung, N.X. (Editors). Plant Resources of South-East Asia No 19. Essential-oil plants. Backhuys Publishers, Leiden, Netherlands. pp. 161–167.
Sources of illustration
• Hallé, N., 1987. Okoubaka Pellegrin & Normand is really a genus of Santalaceae. Bulletin du Muséum National d’Histoire Naturelle, 4e série. Section B, Adansonia, 4: 355–363.
• Louis, J. & Léonard, J., 1948. Octoknemaceae. In: Robyns, W., Staner, P., De Wildeman, E., Germain, R., Gilbert, G., Hauman, L., Homès, M., Lebrun, J., Louis, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 1. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 288–293.
Author(s)
D.O. Ladipo
Centre for Environment, Renewable Natural Resources Management, Research and Development (CENRAD), 5 Akinola Maja Avenue, P.M.B. 5052, Jericho Hills, Ibadan, Nigeria
A.A. Adebisi
Centre for Environment, Renewable Natural Resources Management, Research and Development (CENRAD), P.M.B. 5052, Jericho Hills, Ibadan, Nigeria
C.H. Bosch
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


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, Réduit, 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:
Ladipo, D.O., Adebisi, A.A. & Bosch, C.H., 2008. Okoubaka aubrevillei Pellegr. & Normand. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map wild


1, leafy twig; 2, inflorescence; 3, seed.
Redrawn and adapted by Iskak Syamsudin



dried bark
obtained from
Gudjons