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Euphorbia grantii Oliv.

Protologue
Trans. Linn. Soc. London 29: 144 (1875).
Family
Euphorbiaceae
Vernacular names
African milkbush (En).
Origin and geographic distribution
Euphorbia grantii occurs from eastern DR Congo, Uganda and Kenya south to Tanzania and northern Zambia.
Uses
The milky latex of Euphorbia grantii is used medicinally, despite its toxicity. The latex may cause rupturing of the cornea if it comes into contact with the eyes, and poisoning in people and animals if ingested. In East Africa the latex is applied to wounds to promote blood clotting and tissue healing. The latex is warmed by placing a section of the stem in hot ash, and applied as ear drops to treat earache. In Rwanda and Burundi the diluted latex is drunk to treat infections of tapeworm and other intestinal worms. Stem ash is applied to sores caused by leprosy. In Rwanda a leaf decoction, roasted leaves or leaf sap mixed with beer is taken to treat gonorrhoea.
The roots are a strong purgative and are given to children to chew to treat stomach complaints, whereas adults chew the roots as an emetic to treat epilepsy, poisoning and snakebites. Ground roots are eaten in porridge to treat constipation. The Maasai people use the stems in a tonic that is mixed with soup and given to new mothers after labour. The leaves, bark and roots are boiled and given to cattle, to prevent infection of the uterus when the placenta is expelled.
In Rwanda and Tanzania the latex is added to Acokanthera schimperi (A.DC.) Schweinf. arrow poison.
The stems are taken as a recreational stimulating drug by the Maasai people. Euphorbia grantii is sometimes planted as a hedge.
Properties
Euphorbia grantii, like many related species, has severely irritant effects on the skin and mucosa. The principle toxic constituents in Euphorbia species are diterpenes present in the milky latex. The rubber content of latex from Euphorbia grantii is low (2.5–6.9% of dry latex). From the stem 3-O-methylquercetin and several other 3-methoxyflavones were isolated, exhibiting potent antiviral activity against picornaviruses such as polio-, coxsackie- and rhino-viruses, and against vesicular stomatitis virus at low concentrations (0.01 μg/ml) and with minimal cytotoxicity. Biochemical studies on the mechanism of action of these compounds on poliovirus replication suggested that these 3-methoxyflavones are able to protect the host cells from a virus-induced shutdown of cellular protein synthesis. Naturally occurring and synthetic 3-O-methylquercetin are equally effective. Strikingly, other natural compounds structurally related to 3-O-methylquercetin such as quercetin, catechin, kaempferol, myricetin and rutin do not block poliovirus replication.
In-vivo bioassays have shown that 3-O-methylquercetin has anti-inflammatory activity, with up to 55% and 31% inhibition of acute and chronic inflammation, respectively. Due to its multiple bioactivities, and the absence of ciliotoxicity towards nasal cilia, 3-O-methylquercetin has shown potential as a nasal antirhinoviral drug to treat the common cold.
Botany
A few-stemmed shrub or sparingly branched small tree up to 9 m tall; bark smooth, grey, horizontally grooved; branches semi-succulent, with large prominent closely-set leaf scars and abundant latex. Leaves alternate, simple and entire, sessile, glabrous; stipules glandular, minute, soon falling; blade linear to linear-lanceolate, up to 30 cm ื 3 cm, base rounded, apex acuminate, midrib prominent on the lower surface, pale green. Inflorescence a short-hairy, 3-branched umbel, consisting of clusters of flowers, each cluster called a ‘cyathium’; peduncle up to 10(–15) cm long; branches up to 5(–7) cm long, each forking up to 8 times; bracts sessile, deltoid, c. 4 cm ื 4 cm, base slightly cordate, apex long-acuminate; cyathia c. 1 cm ื 3 cm, with a barrel-shaped involucre, lobes c. 3 mm ื 5 mm, rounded, margin sharply toothed, all parts short-hairy, glands 4, spreading, c. 4 mm ื 8 mm, transversely elliptical, outer margin with 6–10 finger-like processes c. 8 mm long, branching several times at the tips and terminating in minute knobs, the glands yellowish green, with reddish processes; each involucre containing 1 female flower surrounded by many male flowers. Flowers unisexual; male flowers with many fan-shaped, deeply divided, feathery bracteoles, stamen c. 15 mm long; female flowers with curved pedicel up to 1.5 cm long in fruit, perianth with lobes c. 1.5 mm long, ovary superior, short-hairy, 3-celled, styles c. 1 cm long, fused to nearly halfway, with shortly 2-fid thickened stigma. Fruit an almost globose capsule c. 13 mm ื 17 mm, glabrous when mature, tinged purplish, 3-seeded. Seeds almost globose, c. 6 mm ื 5 mm, slightly compressed laterally and obscurely 3-angled, surface minutely rough, greyish brown.
Euphorbia comprises about 2000 species and has a worldwide distribution, with at least 750 species occurring in continental Africa and about 150 species in Madagascar and the Indian Ocean islands. Euphorbia grantii belongs to section Trichadenia, a group of trees, shrubs or perennial herbs with a fleshy rootstock and usually fleshy stems, stipules absent or soon falling or modified into glands, large, terminal, umbel-like inflorescences, glands usually with slender lobes or appendages, relatively large fruits and seeds without a caruncle. Several other Euphorbia spp. of section Trichadenia are used in medicine in tropical Africa. Euphorbia noxia Pax occurs in Somalia and southern Yemen; in Somalia the latex is an ingredient of arrow poison. Euphorbia somalensis Pax occurs in Ethiopia and Somalia. In Somalia the latex is applied to bruised skin caused by mange; it is applied undiluted to the skin of camels and diluted to sheep and goats. The latex of Euphorbia transvaalensis Schltr. from southern Africa is used to treat warts. Euphorbia monteiri Hook.f. belongs to section Pseudeuphorbium which has many characteristics similar to those of section Trichadenia, but the fleshy, tuberous roots are lacking and the stem is succulent with prominent tubercles. Euphorbia monteiri occurs in Angola, Namibia, Botswana, Zimbabwe and South Africa. In Namibia the latex is applied to decaying teeth. An infusion of the crushed roots is drunk as a purgative. Sliced lateral roots are added to boiling milk, which is drunk as a blood purifier and tonic. Crushed roots are added to milk for better butter production. In Botswana a leaf and root decoction is taken to treat biliousness. In southern Zimbabwe the roots are taken as an emetic. Cooked aerial parts are given to aggressive dogs.
Ecology
Euphorbia grantii occurs in sandy or rocky soils, in open woodland, and on rocky hillsides, up to 1750 m altitude.
Genetic resources and breeding
Euphorbia grantii is fairly common throughout its extensive range and there are no signs of genetic erosion.
Prospects
The 3-methoxyflavones isolated from the stem of Euphorbia grantii show interesting antiviral activity and merit further research.
Major references
• Carter, S. & Leach, L.C., 2001. Euphorbiaceae, subfamily Euphorbioideae, tribe Euphorbieae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 5. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 339–465.
• De Meyer, N., Haemers, A., Mishra, L., Pandey, H.K., Pieters, L.A., Vanden Berghe, D.A. & Vlietinck, A.J., 1991. 4-Hydroxy-3-methoxyflavones with potent antipicornavirus activity. Journal of Medicinal Chemistry 34: 736–746.
• Dimova, S., Mugabowindekwe, R., Willems, T., Brewster, M.E., Noppe, M., Ludwig, A., Jorissen, M. & Augustijns, P., 2003. Safety-assessment of 3-methoxyquercitin as an antirhinoviral compound for nasal application: effect on ciliary beat frequency. Journal of Pharmaceutics 263: 95–103.
• Neuwinger, H.D., 1996. African ethnobotany: poisons and drugs. Chapman & Hall, London, United Kingdom. 941 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
Other references
• Catley, A. & Mohammed, A.A., 1996. Ethnoveterinary knowledge in Sanaag region, Somaliland (Part 11): notes on local methods of treating and preventing livestock disease. Nomadic Peoples 38: 1–12.
• Deng, B.-L., Lepoivre, J.A., Lemiere, G., Dommisse, R., Claeys, M., Boers, F. & De Groot, A., 1997. A practical synthesis of 3-methoxyflavones. Liebigs Annalen der Chemie 2169–2175.
• Ichikawa, M., 1987. A preliminary report on the ethnobotany of the Suiei Dorobo in northern Kenya. African Study Monographs, Supplement 7: 1–52.
• Middleton, E., Kandaswami, C. & Theoharides, T.C., 2000. The effects of plant flavonoids on mammalian cells: implications for inflammation, heart disease, and cancer. Pharmacological Reviews 52: 673–751.
• Minja, M.M.J., 1999. The Maasai Wonder Plants. Paper presented at the People & Plants training workshop. Tropical Pesticides Training Institute, 15–18 March, Arusha, Tanzania.
• SEPASAL, 2008. Euphorbia monteiri. [Internet] Survey of Economic Plants for Arid and Semi-Arid Lands (SEPASAL) database. Royal Botanic Gardens, Kew, Richmond, United Kingdom. http://www.kew.org/ ceb/sepasal/. Accessed March 2008.
• Uzabakiliho, B., Largeau, C. & Casadevall, E., 1987. Latex constituents of Euphorbia candelabrum, Euphorbia grantii, Euphorbia tirucalli and Synadenium grantii. Phytochemistry 26(1): 3041–3046.
• van Hoof, L., Vanden Berghe, D.A., Hatfield, G.M. & Vlietinck, A.J., 1984. Plant antiviral agents; V. 3-methoxyflavones as potent inhibitors of viral-induced block of cell synthesis. Planta Medica 50: 513–517.
• Vlietinck, A.J., van Hoof, L., Tott้, J., Lasure, A., Vanden Berghe, D.A., Rwangabo, P.C. & Mvukiyumwami, J., 1995. Screening of hundred Rwandese medicinal plants for antimicrobial and antiviral properties. Journal of Ethnopharmacology 46: 31–47.
• Vrijsen, R., Everaert, L., Van Hoof, L.M., Vlietinck, A.J., Vanden Berghe, D.A. & Boeye, A., 1987. The poliovirus-induced shut-off of cellular protein synthesis persists in the presence of 3-methylquercitin, a flavonoid which blocks viral protein and RNA synthesis. Antiviral Research 7: 35–42.
Author(s)
• O.M. Grace
PROTA Country Office United Kingdom, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, United Kingdom
• D.G. Fowler
Flat 4 Abbotsrood, 1 Milnethorpe Road, Eastbourne BN20 7NR, Sussex, United Kingdom


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, R้duit, 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:
Grace, O.M. & Fowler, D.G., 2008. Euphorbia grantii Oliv. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes m้dicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.