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Solanum erianthum D.Don

Protologue
Prodr. fl. nepal.: 96 (1825).
Family
Solanaceae
Chromosome number
2n = 24
Synonyms
Solanum verbascifolium auct. non L.
Vernacular names
Potato tree, tobacco tree, tropillo (En). Amourette marron (Fr). Maria mole amarga (Po).
Origin and geographic distribution
Solanum erianthum originates from the West Indies, Central America and Mexico, but is now a widespread weed in the tropics, although hardly penetrating South America. It was probably introduced from the Caribbean into West Africa at the time of the slave trade and it is believed to have been introduced into the Philippines by the Spanish in the 16th century, from where it has spread throughout the South-East Asian archipelago and to mainland Asia and Australia as a weed.
Uses
In West Africa a leaf decoction of Solanum erianthum is taken for its diuretic and purgative properties to cure malaria, leprosy and venereal diseases and it is also taken to stimulate the liver functions.
In tropical Asia the leaves are considered a potent medicine for expelling all impurities through the urine, in particular to treat leucorrhoea, and also as an abortifacient. Pounded leaves are applied as a poultice to treat haemorrhoids and scrofula. Heated leaves are applied to the forehead against headache. A decoction of the leaves is drunk to treat vertigo. A decoction of the roots is applied to treat violent body pains or to relieve digestive troubles; it is also given to treat dysentery, diarrhoea and fever. The root bark is used as an antiphlogistic and to treat arthritis. The fruits are an ingredient of arrow poison.
Although the fruits are considered poisonous, causing nausea, headache and cramps, in South-East Asia they are sometimes eaten when cooked. In southern India the fruits are prepared as a curry. In the Philippines the velvety leaves are used to remove grease from dishes. Solanum erianthum is considered suitable as a shade plant for coffee, but in Ghana it is considered an undesirable shade plant. In the Caribbean Solanum erianthum is planted as an ornamental.
Properties
Solanum erianthum contains steroidal saponins and free genins as well as steroidal alkaloids of the spirosolane group. The spirosolanes are structurally similar to saponins of the diosgenin type. Important spirosolane alkaloids include solasodine and tomatidine, which are both found in Solanum erianthum. The total alkaloid content of air dry leaves and fruits is about 0.4%. The solasodine content in fruits from Indian samples was 0.01–0.70%. Leaf samples from Vietnam contained 0.26% solasodine and 0.05% tomatidine.
Steroidal alkaloids such as tomatine, solanine and chaconine inhibit growth and development of a large number of fungi. A flavonoid-rich extract of the leaves of Solanum erianthum possesses antibacterial and antifungal activity against gram-positive bacteria and the fungi Aspergillus flavus and Candida albicans. Steroidal alkaloids from Solanum erianthum are useful in industry as steroid precursors. Solasodine is a nitrogen-containing analogue of diosgenin, a compound often used as raw material for the production of medicinal steroids. The synthetic steroids have three main applications in medicine: as anti-inflammatory corticosteroids, as contraceptive steroids and as anabolic steroids. An aqueous extract of the leaves given orally to mice was effective as a prophylactic against malaria, but when administered 5 days after infection, it failed to suppress the malaria parasites.
Active compounds can be produced in vitro, although only in low amounts. Both diosgenin and solasodine have been isolated from 6-month-old callus, established from sterilized seeds on Murashige and Skoog’s revised medium. Blue light stimulated solasodine synthesis and green light stimulated diosgenin synthesis.
Adulterations and substitutes
Steroidal alkaloids (e.g. diosgenin and tigogenin) are also found in Dioscorea and Smilax species; these are also used as starting material for steroid hormone semisynthesis.
Description
Shrub up to 4(–10) m tall; stem up to 20 cm in diameter, unarmed, densely woolly hairy with soft stellate hairs. Leaves alternate, simple; stipules absent; petiole 2–3(–4) cm long; blade elliptical-ovate, 10–20(–30) cm Χ 3.5–15 cm, base rounded to cuneate, apex acute to acuminate, margin entire or slightly wavy, densely woolly hairy. Inflorescence a terminal or axillary compound cyme, 15–25-flowered. Flowers bisexual, regular, 5-merous; calyx campanulate, c. 5 mm long, lobes ovate; corolla stellate, c. 1.5 cm in diameter, white; stamens alternate with corolla lobes, filaments 1.5 mm long, glabrous, anthers oblong, c. 4 mm long, opening with apical pores; ovary superior, almost glabrous, style glabrous. Fruit a globose berry 8–12 mm in diameter, short-hairy, dull yellow to orange when ripe, many-seeded. Seeds ovoid, compressed, 1–2 mm in diameter. Seedling with epigeal germination; cotyledons thin, leafy.
Other botanical information
Solanum comprises about 1000 species and has a cosmopolitan distribution, except in boreal, alpine and aquatic habitats. About 110 species are found in tropical Africa. The principal centre of diversity is located in Central and South America, with secondary centres in Africa and Australia. Solanum has been subdivided into 7 subgenera and numerous sections and series. Solanum erianthum belongs to subgenus Brevantherum, which has another introduced species present as a weed and ornamental in tropical Africa: Solanum mauritianum Scop.
Ecology
Solanum erianthum occurs in sunny localities, in brushwood and roadsides, on waste ground and in edges of fields and forests. It is also a weed of gardens and fields at low to medium altitudes and prefers a well-drained soil. In Ghana it is frequently encountered as one of the pioneer species of degraded mining sites.
Propagation and planting
Solanum erianthum is easily raised from seed and can also be propagated from shoot cuttings and by division of rooted shoots.
Diseases and pests
Many Solanum spp., including Solanum erianthum, are hosts of diseases and pests that attack economically important Solanaceae.
Yield
In many Solanum species the steroidal alkaloid content and sapogenin content decline as the fruit ripens. Leaf alkaloid and sapogenin contents also decline with age. In India a method has been developed to estimate solasodine content in the leaves 3 months after sowing by estimating their N content. At that stage a top dressing or foliar sprays may be applied to increase the solasodine yield. In related species a yield of 45–50 kg of solasodine per ha is considered reasonable.
Handling after harvest
The leaves and roots can be used fresh or dried and stored in airtight containers for later use.
Genetic resources
In its native range in Central America Solanum erianthum is locally under serious pressure. In view of its weedy nature and wide distribution throughout the tropics however, the risk of genetic erosion seems to be rather limited.
Breeding
The large variation in alkaloid content within Solanum erianthum offers possibilities for selection. However, the alkaloid content also varies substantially as a result of ecological conditions, drying and storage.
Prospects
Solanum erianthum has potential for use in reclamation of degraded sites, and has medicinal and ornamental value. The possibility of its cultivation for extraction of steroidal saponins needs further research. However, introduction in areas where it does not yet occur, should be discouraged as it may become a noxious weed.
Major references
• Blomqvist, M.M., 1997. Taxonomy and uses of medicinally important species in the genera Datura L. and Solanum L. (Solanaceae) in South East Asia. Unpublished MSc. thesis, Department of Plant Taxonomy, Wageningen Agricultural University, the Netherlands. 132 pp.
• Blomqvist, M.M. & Nguyen Tien Ban, 1999. Solanum 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. 453–460.
• 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.
• Makinde, J.M., Obih, P.O. & Jimoh, A., 1987. Effect of Solanum erianthum aqueous leaf extract on Plasmodium berghei berghei in mice. African Journal of Medicine and Medical Sciences 16(4): 193–196.
• Roe, K.E., 1972. A revision of Solanum Section Brevantherum (Solanaceae). Brittonia 24(3): 239–278.
Other references
• Abbiw, D.K., 1990. Useful plants of Ghana: West African uses of wild and cultivated plants. Intermediate Technology Publications, London and Royal Botanic Gardens, Kew, Richmond, United Kingdom. 337 pp.
• Adam, G., Huong, H.T. & Khoi, N.H., 1979. The constituents of the Vietnamese drug plant Solanum verbascifolium L. Planta Medica 36: 238–239.
• Ajasa, A.M.O., Bello, M.O., Ibrahim, A.O., Ogunwande, I.A. & Olawore, N.O., 2004. Heavy trace metals and macronutrients status in herbal plants of Nigeria. Food Chemistry 85(1): 67–71.
• Barnabas, C.G.G. & Nagarajan, S., 1988. Antimicrobial activity of flavonoids of some medicinal plants. Fitoterapia 59(6): 508–510.
• Everitt, J.H., 1977. Native potato tree (Solanum erianthum D.Don) grown as an ornamental. Journal of the Rio Grande Valley Horticultural Society 31: 145–146.
• Garland, T. & Barr, C. (Editors), 1998. Toxic plants and other natural toxicants. CAB International, Wallingford, United Kingdom. 585 pp.
• Jain, S.C., Sahoo, S.L. & Vijvergia, R., 1995. Influence of light on growth and production of steroids and glycoalkaloids in Solanum species in vivo and in vitro. Indian Journal of Pharmaceutical Sciences 57(3): 100–101.
• Karikari, R., 2006. Natural regeneration of indigenous tree species on reclaimed mined land: a case study of Anglogold Company Limited, Obuasi. B.Sc. Thesis, Natural Resources Management, Department of Silviculture and Forest Management, Faculty of Renewable Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. 20 pp.
• Kaul, B.L. & Zutshi, U., 1982. Cultivation of Solanum khasianum Clarke for steroids. In: Atal, C.K. & Kapur, B.M. (Editors). Cultivation and utilization of medicinal plants. Regional Research Laboratory Jammu-Tawi, New Delhi, India. pp. 98–106.
• Nasir, Y.J., 1985. Solanaceae. In: Nasir, E. & Ali, S.I. (Editors). Flora of Pakistan No 168. National Herbarium, Pakistan Agricultural Research Council, Islamabad and Department of Botany, University of Karachi, Pakistan. 62 pp.
• Neser, S., Zimmermann, H.G., Erb, H.E. & Hoffmann, J.H., 1990. Progress and prospects for the biological control of two Solanum weeds in South Africa. In: Proceedings of the 8th international symposium on biological control of weeds. pp. 371–381.
• Roe, K.E., 1967. A revision of Solanum Sect. Brevantherum (Solanaceae) in North and Central America. Brittonia 19(4): 353–373.
• Roe, K.E., 1968. Solanum verbascifolium L., misidentification and misapplication. Taxon 17(2): 176–179.
Sources of illustration
• Blomqvist, M.M. & Nguyen Tien Ban, 1999. Solanum 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. 453–460.
Author(s)
• D.M. Modise
University of South Africa, P.O. Box 392, Pretoria 0003, South Africa
• K.K. Mogotsi
Botswana College of Agriculture, Private Bag 0027, Gaborone, Botswana
Based on PROSEA 12(1): ‘Medicinal and poisonous plants 1’.

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, Rιduit, 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:
Modise, D.M. & Mogotsi, K.K., 2008. Solanum erianthum D.Don. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes mιdicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map naturalized


1, flowering branch; 2, flower; 3, infructescence.
Source: PROSEA



young infructescence
obtained from
Calphotos


infructescence
obtained from
Calphotos