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Strychnos icaja Baill.

Adansonia 12: 368 (1879).
Chromosome number
2n = 44
Vernacular names
Curare, strychnos, icaja (En).
Origin and geographic distribution
Strychnos icaja occurs from Guinea east to the Central African Republic and south to Angola.
Because of its toxicity Strychnos icaja is usually administered under the supervision of a traditional medicine man, mainly in the treatment of skin diseases and chronic and persistent malaria. In Ghana an alcoholic extract of stem bark is taken to treat haemorrhoids. In the Central African Republic the body is rubbed with a root bark maceration as a snake repellent. A very small dose of root bark maceration is taken as an abortifacient and as an anthelmintic. In Gabon a root decoction is taken as a diuretic or as an intoxicating drink. In Congo a cold infusion of the root in palm wine is taken to treat gastrointestinal complaints and hernia. In DR Congo ground root bark mixed with palm oil is applied to treat skin diseases and itch. The ash of burnt twigs or roots is rubbed into scarifications of the forehead to treat insanity and malaria. A maceration of ground roots is used as a rectal wash to treat sterility. Throughout Central Africa a root or root bark infusion, or more rarely a stem bark extract, has been used as ordeal poison. Often roots of young plants were used, which seem to have a lower toxicity than those of mature plants. The root bark is an ingredient in arrow poison. In Côte d’Ivoire, Nigeria and DR Congo whole plants, root bark and fruits are used as a fish poison.
The root, stem and leaves contain a mixture of tertiary indole alkaloids of which strychnine and pseudostrychnine (12-hydroxystrychnine) are the principal active substances. The roots contain dimeric tertiary alkaloids such as bisnordihydrotoxiferine and sungucine. They also contain quaternary alkaloids, such as N-strychninium. Strychnine is also the main alkaloid component of the fruits and seeds. Strychnine activity enhances epinephrine levels and increases blood pressure. The most direct symptoms caused by strychnine are violent convulsions. It is applied in medicine as a stimulator of the nervous system and as a reliable anaesthetic. It is slightly soluble in water, but more soluble in alcohol. Strychnos icaja could be used as a local source either of an extract or of a partially purified mixture of strychnine, 12-hydroxystrychnine, and other tertiary alkaloids. Sungucine and isosungucine exhibit antiplasmodial activities but also show cytotoxic effects against human cancer cells. Pharmacological experiments have shown that the quaternary alkaloid fraction has pronounced muscle-relaxant activity. Moreover, this fraction has a powerful cardiotoxic action ending in irreversible cardiac arrest.
Other alkaloids of the leaves are the monomers protostrychnine, genostrychnine and pseudostrychnine, the bisindolic alkaloid strychnogucine, and the trimeric indolomonoterpenic alkaloid strychnohexamine, which has antiplasmodial activity against Plasmodium falciparum.
Strychnogucine and strychnohexamine were also isolated from the root bark.
Saponins, iridoids and phenolic compounds are also present in Strychnos icaja, but they probably have little activity compared to the alkaloids.
In-vitro production of strychnine and some other Strychnos alkaloids is possible.
Adulterations and substitutes
Several other tropical African plant species such as Strophanthus spp. are used as substitutes for Strychnos icaja to produce arrow poison.
Large liana up to 100 m long, climbing with solitary tendrils; stem up to 15 cm in diameter; branchlets dark green, glabrous. Leaves opposite, simple and entire; stipules absent; petiole 4–12 mm long, glabrous; blade ovate to elliptical, 5–15(–21) cm × 2–7(–10) cm, base cuneate to rounded, apex acuminate, glabrous, 3-veined from the base. Inflorescence an axillary lax thyrse 3–7 cm long, few- to many-flowered. Flowers bisexual, regular, 4-merous; sepals fused at base, broadly ovate to almost orbicular, up to 1 mm long; corolla tube up to 1.5 mm long, lobes oblong to ovate or triangular, 1.5–2 mm long, acute, spreading, glabrous or hairy inside at base, greenish yellow or yellowish white; stamens inserted at the mouth of the corolla tube, exserted; ovary superior, globose, c. 0.5 mm in diameter, glabrous, 2-celled, style 0.5–1 mm long, stigma small, head-shaped. Fruit an ellipsoid or globose berry c. 2.5 cm × 3 cm, soft, dark yellow when ripe, 1-seeded. Seed ellipsoid, 16–21 mm × 15–20 mm × 9–15 mm, woolly hairy.
Other botanical information
Strychnos comprises about 200 species: about 60 species in Asia, 65 in America and 75 in Africa. Strychnos icaja belongs to the section Breviflorae.
Strychnos icaja occurs in rainforest and secondary forest on lateritic sandy clay soils, from sea-level up to 800 m altitude.
Propagation and planting
Strychnos icaja regenerates from seed and suckers.
The roots are dug up and the bark is removed before the root dries out. Harvesting the stem bark or the leaves is a more sustainable activity.
Handling after harvest
After drying and grinding, the material can be subjected to a conventional alkaloid extraction procedure.
Genetic resources
There are no indications that Strychnos icaja is in danger of genetic erosion.
Because of its alkaloid content Strychnos icaja is widely used for medicinal purposes. In order to promote its sustainable use, research should be done on domestication and improving its productivity for industrial production with respect to local and international trade. Research on the antimalarial properties of some of the alkaloids seems promising.
Major references
• Bisset, N.G., 1970. The African species of Strychnos. Part I. The ethnobotany. Lloydia 33(2): 201–243.
• Bisset, N.G. & Leeuwenberg, A.J.M., 1968. The use of Strychnos species in Central African ordeal and arrow poisons. Lloydia 31: 208–222.
• Bisset, N.G. & Phillipson, J.D., 1971. The African species of Strychnos. Part 2. The alkaloids. Lloydia 34(1): 1–60.
• Bohlin, L., 1978. Some Strychnos alkaloids: their occurrence, structure and biological activity. Acta Universitatis Upsaliensis 32, Uppsala, Sweden. 68 pp.
• FAO, 1986. Some medicinal forest plants of Africa and Latin America. FAO Forestry Paper 67. Rome, Italy. 252 pp.
• Iwu, M.M., 1993. Handbook of African medicinal plants. CRC Press, Boca Raton, Florida, United States. 464 pp.
• Leeuwenberg, A.J.M., 1969. The Loganiaceae of Africa 8. Strychnos 3. Revision of the African species with notes on the extra-African. Mededelingen Landbouwhogeschool Wageningen 69–1. Wageningen, Netherlands. 316 pp.
• Mshana, N.R., Abbiw, D.K., Addore-Mensah, I., Ekpere, J.A., Enow-Orock, E.G., Gbile, Z.O., Noamessi, G.K., Odei, M.A., Odunlami, H., Oteng-Yeboah, A.A., Sarpong, K., Sofowora, A. & Tackie, A.N., 2000. Traditional medicine and pharmacopoeia. Contribution to the revision of ethnobotanical and floristic studies in Ghana. Organisation of African Unity / Scientific, Technical and Research Commission. 920 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Ohiri, F.C., Verpoorte, R. & Baerheim Svendsen, A., 1983. The African Strychnos species and their alkaloids: a review. Journal of Ethnopharmacology 9(2–3): 167–223.
Other references
• Adjanohoun, E.J., Ahyi, A.M.R., Aké Assi, L., Baniakina, J., Chibon, P., Cusset, G., Doulou, V., Enzanza, A., Eymé, J., Goudoté, E., Keita, A., Mbemba, C., Mollet, J., Moutsamboté, J.-M., Mpati, J. & Sita, P. (Editors), 1988. Médecine traditionnelle et pharmacopée - Contribution aux études ethnobotaniques et floristiques en République Populaire du Congo. Agence de Coopération Culturelle et Technique, Paris, France. 606 pp.
• Bisset, N.G. & Khalil, A.A., 1976. New alkaloids from Strychnos icaja. Phytochemistry 15: 1973–1976.
• Bisset, N.G., Das, B.C. & Parello, J., 1973. Alkaloids from the leaves of Strychnos icaja Baill. Tetrahedron 29: 4137–4148.
• Caniato, R. & Puricelli, L., 2003. Review: natural antimalarial agents (1995–2001). Critical Reviews in Plant Sciences 22(1): 79–105.
• Frédérich, M., Bentires-Ali, M., Tits, M., Angenot, L., Heinen, E. & De Pauw-Gillet, M.-C., 2003. Apoptosis induction in human cancer cells by sungucine from Strychnos icaja root. Naunyn-Schmiedeberg’s Archive of Pharmacology 367: 260–265.
• Frédérich, M., De Pauw, M.-C., Llabrès, G., Tits, M., Hayette, M.P., Brandt, V., Penelle, J., De Mol, P. & Angenot, L., 2000. New antimalarial and cytotoxic sungucine derivatives from Strychnos icaja roots. Planta Medica 66(3): 262–269.
• Frédérich, M., De Pauw, M.-C., Prosperi, C., Tits, M., Brandt, V., Penelle, J., Hayette, M.-P., De Mol, P. & Angenot, L., 2001. Strychnogucines A and B, two new antiplasmodial bisindole alkaloids from Strychnos icaja. Journal of Natural Products 64(1): 12–16.
• Frédérich, M., Tits, M. & Angenot, L., 2003. Indole alkaloids from Strychnos species and their antiplasmodial and cytotoxic activities. Chemistry of Natural Compounds 39(6): 513–519.
• Gassita, J.N., Nze Ekekang, L., De Vecchy, H., Louis, A.M., Koudogbo, B. & Ekomié, R. (Editors), 1982. Les plantes médicinales du Gabon. CENAREST, IPHAMETRA, mission ethnobotanique de l’ACCT au Gabon, 10–31 juillet 1982. 26 pp.
• Kambu, K., Coune, C. & Angenot, L., 1979. Nouveaux alcaloïdes des racines du Strychnos icaja. Planta Medica 37: 161–164.
• Lamotte, J., Dupont, L., Dideberg, O., Kambu, K. & Angenot, L., 1979. Isolation and structure of sungucine, a new type of bisindole alkaloid. Tetrahedon Letters 43: 4227–4228.
• Philippe, G., Angenot, L., Tits, M. & Frédérich, M., 2004. About the toxicity of some Strychnos species and their alkaloids. Toxicon 44(4): 405–416.
• Philippe, G., De Mol, P., Zeches-Hanrot, M., Nuzilland, J.M., Tits, M.H., Angenot, L. & Frédérich, M., 2003. Indoloterpenic alkaloids from Strychnos icaja roots. Phytochemistry 62(4): 623–629.
• Raponda-Walker, A. & Sillans, R., 1961. Les plantes utiles du Gabon. Paul Lechevalier, Paris, France. 614 pp.
Sources of illustration
• Leeuwenberg, A.J.M., 1969. The Loganiaceae of Africa 8. Strychnos 3. Revision of the African species with notes on the extra-African. Mededelingen Landbouwhogeschool Wageningen 69–1. Wageningen, Netherlands. 316 pp.
D.M. Mosango
c/o Laboratory of Natural Sciences, Lycée Français Jean Monnet de Bruxelles (LFB), Avenue du Lycée Français 9, 1180 Brussels, Belgium

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

Correct citation of this article:
Mosango, D.M., 2007. Strychnos icaja Baill. 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, flowering branch; 2, flower; 3, fruit.
Redrawn and adapted by Achmad Satiri Nurhaman