Prota 11(1): Medicinal plants/Plantes médicinales 1
Hook., Niger Fl.: 508 (1849).
Origin and geographic distribution
Pycnocoma macrophylla is native from Sierra Leone and Liberia eastwards to Gabon and DR Congo.
All parts of Pycnocoma macrophylla are strongly purgative. Root bark, the most widely used plant part throughout West Africa, is not administered to children in Côte d’Ivoire because of its strong purgative action. In Ghana the stem bark is ground, mixed with water and lemon juice and drunk as an emetic. It is also used as a fish poison.
Highly active protein kinase C-agonizing compounds were isolated from the leaves and identified as esters of the diterpenoid 11,18-dehydro-phorbol and of 4,12-dideoxy-16-hydroxy-phorbol. These phorbol derivatives stimulated the central nervous system by markedly inhibiting amphetamine-induced locomotor activity in mice. A root extract exhibited antitumour activity in the P388 lymphocytic leukaemia test; scopoletin was found to be partly responsible for this effect.
Monoecious shrub up to 3 m tall; stems glabrous. Leaves alternate, clustered towards end of branches, simple; stipules falling early; petiole up to 1 cm long, glabrous; blade oblanceolate, 25–60 cm × 5–14 cm, base rounded to cordate, apex acuminate, margins entire, toothed or rarely lobed, glabrous, with 16–22 pairs of lateral veins, small pustules below and paired glands at lower surface towards the base. Inflorescence an axillary, solitary raceme 11–20 cm long with flowers in clusters of usually 3 male flowers and 1 terminal female flower; peduncle glabrous to densely short-hairy; bracts ovate, 4–8 mm long. Flowers unisexual, regular, with strong, repellent smell; petals absent; male flowers with pedicel 1.5–2.5 cm long, calyx lobes c. 6 mm long, stamens many, free, anthers small; female flowers with pedicel 2–7 mm long, calyx lobes 6–9 mm long, ovary superior, 2–3 mm in diameter, slightly 3-lobed, densely short-hairy, 3-celled, styles 3, fused below. Fruit a 3-lobed, 6-horned capsule c. 2 cm in diameter, glabrous to densely short-hairy, 3-seeded. Seeds globose, c. 13 mm in diameter, smooth, brown.
The growth of Pycnocoma macrophylla follows Corner’s architectural model implying that vegetative growth of a single meristem produces a single unbranched axis with lateral inflorescences.
Pycnocoma comprises about 18 species, all in tropical Africa. About 10 occur in DR Congo, several with a very localized distribution.
Pycnocoma angustifolia Prain occurs in Sierra Leone, Liberia, Côte d’Ivoire, Ghana and Nigeria and Pycnocoma cornuta Müll.Arg. occurs in Ghana and Nigeria. In Ghana intermediates between Pycnocoma macrophylla and these two species occur, indicating that they could well belong to a single species. Their medicinal uses are similar to those of Pycnocoma macrophylla.
Pycnocoma chevalieri Beille occurs in gallery forest in the Central African Republic, northern DR Congo, Sudan and Uganda. In DR Congo ground roots are added to wine and the mixture is drunk as an emetic. They are also eaten with palm nuts or rice as a purgative. In the Central African Republic the leaves are used as a cure for diabetes. Pycnocoma littoralis Pax is a vulnerable species restricted to the coastal belt of southern Kenya and northern Tanzania. In Tanzania a root decoction is drunk to expel a retained placenta. Pycnocoma minor Müll.Arg. occurs in Equatorial Guinea and Gabon. In Gabon the macerated roots are added to wine and the mixture is drunk as a diuretic. A root extract of Pycnocoma thonneri Pax, endemic to DR Congo, is drunk as an abortifacient, purgative and anthelmintic. Root scrapings are eaten to cure stomach-ache and to kill internal parasites. Root powder or leaf sap is applied as eye drops to stop convulsions in children. Root scrapings are applied as a dressing to counteract inflammation in the knee.
Pycnocoma macrophylla occurs in the undergrowth of forests. In DR Congo it is restricted to 500–750 m altitude.
Genetic resources and breeding
Pycnocoma macrophylla is widespread and not under serious threat.
More chemical and pharmacological research is needed to evaluate the potential of Pycnocoma macrophylla.
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Correct citation of this article:
Bosch, C.H., 2008. Pycnocoma macrophylla Benth. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.