Datura metel (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Vegetable
Stimulant
Dye / tannin
Medicinal
Timber
Ornamental
Food security

Datura metel L.

Protologue: Sp. pl. 1: 179 (1753).

Family: Solanaceae

Chromosome number: 2n = 24, 48

• Datura fastuosa L. (1759).

• Downy thorn apple, metel thorn apple, metel (En).
• Métel, stramoine métel, concombre diable, concombre à chien, trompette de la mort (Fr).
• Cornucopia, trombetão-roxo, trombeta do juízo, burbiaca (Po).
• Mnanaha, mnawha, mnaraha, mranaha, mvundovundo wa chamboni, muranha (Sw).

Datura metel is native to the Americas and has been introduced from there throughout the tropics and subtropics. It is probably grown throughout tropical Africa as an ornamental. It is documented as a naturalized weed in many African countries but is probably seriously under-reported.

Datura metel and Datura stramonium L. have largely similar medicinal uses throughout the world. In tropical Africa as well as in Asia the most widely documented use of Datura metel is for relieving asthma, cough, tuberculosis and bronchitis by smoking the dried leaves, roots or flowers as a cigarette or in a pipe. These ‘asthma cigarettes’ have been shown to be very effective in some cases, but in other cases they had little or no effect. Cigarettes made with the leaves are also used to treat Parkinson’s disease. Widespread is also the use of different plant parts in various preparations for sedating patients with mental disorders. In Africa other traditional uses of the leaves include the treatment of haemorrhoids, boils, sores, skin diseases, rheumatism, headache, toothache, cholera, parasites such as ringworm and guinea worm, and as an abortifacient and anaesthetic. In Senegal, Guinea, Ghana and Nigeria crushed leaves are applied as poultices on inflammatory swellings and rheumatic joints. In Ghana a decoction of the leaves is used as eye drops to cure conjunctivitis and other eye complaints. In Nigeria dried leaves are mixed with salt and pepper and burnt to treat asthma. In Ethiopia the seed oil is used for massaging painful body parts. In Asia Datura metel has similar medicinal applications, and it is used additionally to treat hydrophobia, epilepsy, convulsion, syphilis, inflammation of the breasts, smallpox, mumps and leprosy.

Datura metel is also widely used as a pesticide. Seeds mixed with sorghum flour are used as poison bait for rats. Plant extracts have been used successfully against caterpillar pests in forestry, cotton pathogens and domestic vermin such as fleas and jigger, and to reduce insect damage in stored wheat and maize. They are useful to control the root knot nematode, Meloidogyne javanica. In Tanzania an extract made from the roots is sprinkled in houses to repel snakes.

In Africa Datura metel has ritual uses in many countries, e.g. in initiation rites in Nigeria and Mozambique. Most commonly the leaves are smoked, or they are boiled and eaten; seeds are similarly used. Roots, seeds or leaves are added to alcoholic drinks to increase the intoxicating effect. Side effects include dry mouth and throat, eye pain, blurred vision, restlessness, dizziness, cardiac arrythmia, flushing and faintness. An overdose will cause headache, nausea, vomiting and affect the central nervous system causing symptoms including disorientation, hallucinations, euphoria, inappropriate affect, short-term memory loss and coma. The seeds are also used for criminal purposes. Hospital admissions and fatalities, most often of adolescents, are not uncommon. It is for this reason that several countries including France removed datura cigarettes from the Pharmacopoeia in 1992.

Datura metel is commonly cultivated as an ornamental, particularly types with double flowers and purple flowers. In East Africa the leaves are used to dye cloth green. In Ethiopia the seed oil is rubbed into fresh hides as a first step in the curing process.

No trade statistics are available for Datura metel, although it is occasionally used for industrial extraction of tropane alkaloids. At the beginning of the 1980s the market prices of scopolamine hydrobromide and hyoscyamine sulphate were approximately US$ 850/kg and US$ 470/kg, respectively.

The leaves of Datura metel contain 0.2–0.6% tropane alkaloids, the flowers 0.1–1.0% and the seeds 0.2–0.5%. In tetraploid plants alkaloid content is almost double that of diploid plants. Scopolamine (= hyoscine) is the major constituent in mature leaves (up to 75% of the total alkaloid content). Other alkaloids are hyoscyamine (= (–)-hyoscyamine or (–)-atropine), norhyoscyamine, norscopolamine, hydroxy-6-hyoscyamine and meteloidine. Although atropine (= (+)-atropine or (+)-hyoscyamine) has often been reported to be present in Datura spp., it is unclear whether it is really a natural product or an artefact obtained during isolation. Scopolamine and hyoscyamine are anticholinergics. They act by competitively and reversibly inhibiting the neuro-transmitter acetylcholine from binding to its muscarinic receptors and this antagonism leads to sympathomimetic-like effects in the organs. They increase the heart rate, induce relaxation and motor inhibition in smooth muscles, decrease secretions, and induce dilation of the pupils of the eyes. Although at low doses their action tends to be depressant and sedative, at high doses they cause substantial excitation: agitation, disorientation, exaggerated reflexes, hallucinations, delirium, mental confusion and insomnia. Hyoscyamine is used to provide symptomatic relief of various gastrointestinal disorders including spasms, peptic ulcers, irritable bowel syndrome, pancreatitis, colic and inflammation of the bladder. It has also been used to relieve some heart problems, to reduce excess saliva production and control some of the symptoms of Parkinson’s disease. Scopolamine is used in ophthalmology to dilate pupils, as an analgesic and to prevent motion sickness.

In-vitro production of scopolamine and hyoscyamine is feasible, though uneconomical. Cultures of hairy roots of Datura metel are the most productive. The growth and production of hyoscyamine and scopolamine in in-vitro root cultures was encouraged by using Gamborg’s B5 liquid medium with half-strength salts. In this medium the excretion of scopolamine rose from 8.7% to 70%. Biomass and alkaloid production also increased when the permeabilizing agent Tween 20 was added for 24 hours after 2 and 4 weeks of culture. After 4 weeks, biomass yield was 2.3 mg/l per day and scopolamine yield 0.84 mg/l per day.

Several withanolides have been identified from the flowers and aerial parts of Datura metel, some of these with cytotoxic activity.

The seed of Datura metel contains about 16% oil with an approximate fatty acid composition of palmitic acid 14%, oleic acid 30% and linoleic acid 52%. The oil also contains considerable quantities of sterols (about 13.4 g/kg) and tocopherols (about 3.4 g/kg) which are considered to be of medicinal interest.

Tropane alkaloids similar to those found in Datura are known from several other Solanaceae (e.g. hyoscyamine and scopolamine in Atropa belladonna L. and Hyoscyamus spp.). Scopolamine is found in high quantity in Duboisia spp., which are used for industrial production in Australia.

Annual or short-lived perennial erect herb up to 2 m tall, often much-branched; stem short-hairy to glabrous. Leaves alternate, simple; stipules absent; petiole up to 16 cm long; blade ovate to often slightly angular, 4–25 cm × 2–20 cm, base cuneate, rounded or truncate, apex acute to acuminate or obtuse, margin entire to coarsely toothed, with or without prickles and stellate hairs, pinnately veined. Flowers axillary, solitary, rarely paired, bisexual, regular, 5-merous; pedicel 5–11 mm long, up to 20 mm long in fruit; calyx tubular, 4–7.5 cm long, lobes almost equal, 0.5–2.5 cm long; corolla trumpet-shaped to tubular, 12–19 cm long, white, yellow, violet or purplish; stamens inserted above the middle of the corolla tube, alternate with corolla lobes, included, filaments short and thick, anthers yellow; ovary superior, 2–6-celled, style slender, up to 13(–17) cm long, stigma small, 2-lobed. Fruit an upright or nodding, ovoid or almost globose capsule up to 4 cm × 3.5 cm, reddish brown to purplish, spines few to many, stout, conical, usually many-seeded. Seeds almost D-shaped, flattened, 4–6 mm × 4–5 mm × c. 1.5 mm, white, yellowish brown or brown. Seedling with epigeal germination; cotyledons thin, leafy.

Datura comprises about 10 species, which all originated in the New World; most species have been introduced throughout the world. Datura metel belongs to section Dutra and is easily confused with other Datura spp., especially Datura inoxia Mill., but the latter species is characterized by the long, soft spines on the fruit and the short-hairy stem and leaves. It is practically impossible to separate ethnobotanical records on the 2 species, also in Africa, and they probably have similar medicinal uses. Brugmansia is considered here as a separate genus, although it is often treated as a section of Datura (section Brugmansia). It mainly differs in its habit (a woody, comparatively long-lived shrub or small tree), its mode of growth (reproducing vegetatively by root suckers), its pendulous or inclined flowers open throughout anthesis for 4–6 days with spathe-like, not circumscissile calyx and long pedicel, and its fruit being a usually indehiscent, unarmed berry. Chemically, Datura and Brugmansia are similar, and consequently they have similar medicinal applications. However, the primary use of the Brugmansia species is ornamental.

Only the basal part of the stem remains vegetative; flowering occurs on the branched part of the plant and branches do not resume vegetative growth after flowering and fruiting. The flowers are closed during the day and open in the evening, and are reported to be pollinated by hawk moths and to be largely self fertile.

In studies in India it was found that mature leaves of about the middle of the stems of Datura metel had the maximum alkaloid content, and that very young fruits possessed a higher content of alkaloids than older fruits. In Datura metel grown experimentally in Iran, the highest scopolamine concentrations were found in the stems (0.3%) and young leaves (0.25%) of 6-week-old plants and in the roots (0.2%) of 16-week-old plants.

Datura metel is locally abundant in waste places, roadsides, brushwood, open grassland, teak forest and on river banks, from sea-level up to 1000 m altitude. It tolerates various soil types but prefers clayey or loamy soils. Datura metel, often with a double and purplish corolla, is widely cultivated in gardens.

Datura metel is generally cultivated from seed sown either directly in the field or in a nursery bed. Soaking seed overnight improves germination. Per ha, 7–8 kg of seed is needed. Seed starts germinating after about 2 weeks, and germination is complete after one month. If the seed is sown in a nursery, seedlings are transplanted when 8–12 cm tall. Normal spacing is 70–100 cm.

Weeding and thinning of a direct sown crop should be done when the plants are about 10 cm tall; a second weeding is done one month later. Irrigation may be necessary and should be done at intervals of 10–15 days.

Datura metel is a host for many diseases and pests that affect solanaceous crops. It can be infected by wilt and root rot caused by the fungus Sclerotium rolfsii, root rot caused by the fungus Corticium solani (synonym: Thanatephorus cucumeris) and by several virus diseases that cause symptoms like leaf curl, retarded growth and yellowing of leaves. Alternaria crassa, a fungus that causes leaf spot and can kill Datura spp., has not yet been reported from tropical Africa.

When flowering starts, about 4 months after sowing, tender branches and leaves are harvested. Several more harvests are possible at intervals of 1–2 months. Fruits are harvested when ripe.

In Nigeria the total alkaloid content of Datura metel has been shown to peak in the hot and dry season, and it was lowest in the rainy season. In India, yields per ha of 10.5–14.5 t of fresh plant material and 750–1200 kg of seed of Datura metel have been reported.

The tender branches and leaves are dried in the shade. Fruits are dried in the sun till they dehisce. The seeds are separated by threshing and after further drying packed for transport.

Datura metel has an extremely wide geographical distribution, prefers anthropogenic habitats and is therefore not liable to genetic erosion.

In order to develop industrial plantations for alkaloid extraction, research should focus on breeding for a high alkaloid content, combined with the development of proper means of vegetative propagation. In India some improved cultivars have been released. Producing and selecting interspecific hybrids of Datura for high scopolamine production, succesfully done with Brugmansia in Ecuador, is promising.

Although the tropane alkaloids scopolamine, hyoscyamine and atropine can be prepared synthetically, it is more economical to extract them from plants such as Datura spp. However, Atropa, Duboisia and Hyoscyamus species are the major sources of raw materials. On the world market of pure tropane alkaloids, it will be difficult for African producers to compete with producers in China, India and Australia.

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• Sri Hartati, Imastini Dinuriah & Blomqvist, M.M., 1999. Datura L. In: de Padua, L.S., Bunyapraphatsara, N. & Lemmens, R.H.M.J. (Editors). Plant Resources of South-East Asia No 12(1). Medicinal and poisonous plants 1. Backhuys Publishers, Leiden, Netherlands. pp. 229–234.

• O.O. Nuga, Department of Forestry and Wildlife, Faculty of Agriculture, University of Port Harcourt, P.M.B. 5323, Port Harcourt, Nigeria

• M.P. Setshogo, Department of Biological Sciences, University of Botswana Herbarium, Private Bag UB00704, Gaborone, Botswana

Nuga, O.O. & Setshogo, M.P., 2008. Datura metel L. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 3 April 2025.

• See the Prota4U database.