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Prota 11(1): Medicinal plants/Plantes médicinales 1
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Strychnos myrtoides Gilg & Busse

Protologue
Bot. Jahrb. Syst. 32: 178 (1902).
Family
Loganiaceae
Origin and geographic distribution
Strychnos myrtoides occurs in south-eastern Tanzania, Mozambique and Madagascar.
Uses
In Madagascar an infusion or decoction of Strychnos myrtoides together with chloroquine is taken to treat malaria.
Properties
Two major indole alkaloids, strychnobrasiline and malagashanine, were isolated from the stem bark, as well as 4 minor alkaloids: malagashanol, 12-hydroxy-19-epi-malagashanine, myrtoidine and 11-demethoxymyrtoidine. These compounds showed no intrinsic antimalarial effect against a chloroquine-resistant strain of Plasmodium falciparum in vitro and in vivo, but significantly enhanced the effect of chloroquine. No cytotoxicity was observed. A crude stem-bark extract also showed no intrinsic antimalarial effects, but significantly enhanced the action of chloroquine both in vitro and in vivo against a chloroquine-resistant Plasmodium yoelii strain in mice.
Botany
Much-branched shrub or small tree up to 5 m tall, often dichotomously branched; branchlets hairy. Leaves opposite, simple and entire; stipules absent; petiole up to 2 mm long, hairy; blade ovate, narrowly ovate to narrowly elliptical, obovate or sometimes nearly orbicular, (0.5–)1–3.5 cm × 0.5–2 cm, base cuneate to rounded, apex rounded to acute or acuminate, glabrous or sparingly hairy on the veins on both sides or only beneath, 3-veined from the base. Inflorescence a terminal, lax thyrse 0.5–1.5(–2) cm long, few-flowered; peduncle short, brown hairy. Flowers bisexual, regular, (4–)5-merous; sepals fused at base, broadly ovate to orbicular, c. 1 cm long; corolla tube bell-shaped to nearly cylindrical, 1–2.5 mm long, lobes narrowly triangular, 1–2 cm long, acute, outside glabrous or minutely hairy, inside hairy at the base, white; stamens inserted at the middle of the corolla tube, included, anthers orbicular or oblong, hairy at the deeply cordate base; ovary superior, ovoid, c. 1 mm × 0.5 mm, 2-celled, style up to 0.5 mm long, stigma head-shaped. Fruit a globose or flattened berry 8–9 mm in diameter, soft, red or orange, 1-seeded. Seed elliptical, flattened, disk-like, 8 mm × 7 mm × 1.5 mm, rough, with thick, short hairs.
Strychnos comprises about 200 species: about 60 species in Asia, 65 in America and 75 in Africa. Strychnos myrtoides belongs to the section Penicillatae. Strychnos diplotricha Leeuwenb., which is endemic to Madagascar, also belongs to this section. It is used as an antimalarial in north-eastern Madagascar. The root bark of Strychnos diplotricha contains indole alkaloids that have also been isolated from the leaves or stem bark of Strychnos myrtoides.
Ecology
Strychnos myrtoides occurs in Brachystegia-woodlands and open forest, from sea-level up to 600 m altitude.
Genetic resources and breeding
Strychnos myrtoides does not seem to be in danger of genetic erosion.
Prospects
The importance of Strychnos myrtoides as traditional antimalarial medicine will probably increase because of its proven effect of enhancing the action of chloroquine in case of chloroquine-resistance. In view of the pharmacologically interesting compounds found in other Strychnos species, more research into the chemical composition and pharmacological activities of the indole alkaloids of Strychnos myrtoides seems warranted.
Major references
• 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.
• Rasoanaivo, P., Ratsimamanga-Urverg, S., Milijaona, R., Rafatro, H., Rakoto-Ratsimamanga, A., Galeffi, C. & Nicoletti, M., 1994. In vitro and in vivo chloroquine-potentiating action of Strychnos myrtoides alkaloids against chloroquine-resistant strains of Plasmodium malaria. Planta Medica 60(1): 13–16.
• Schwikkard, S. & van Heerden, F.R., 2002. Antimalarial activity of plant metabolites. Natural Product Reports 19: 675–692.
Other references
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Ramanitrahasimbola, D., Rasoanaivo, P., Ratsimamanga, S. & Vial, H., 2006. Malagashanine potentiates chloroquine antimalarial activity in drug resistant Plasmodium malaria by modifying both its efflux and influx. Molecular and Biochemical Parasitology 146(1): 58–67.
• Rasoanaivo, P., Palazzino, G., Nicoletti, M. & Galeffi, C., 2001. The co-occurrence of C(3) epimer Nb,C(21)-secocuran alkaloids in Strychnos diplotricha and Strychnos myrtoides. Phytochemistry 56: 863–867.
Author(s)

•	A. de Ruijter 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

Correct citation of this article:
de Ruijter, A., 2007. Strychnos myrtoides Gilg & Busse. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.