Prota 11(1): Medicinal plants/Plantes médicinales 1
Fl. aegypt.-arab.: 38 (1775).
2n = 22
Grey leaf heliotrope (En).
Origin and geographic distribution
Heliotropium ovalifolium is widespread in tropical and subtropical Africa including Madagascar. Its range extends to tropical Asia and Australia.
Heliotropium ovalifolium is used against syphilis in at least 3 different African countries and is reported to have analgesic properties. In Tanzania the dried plant is mixed with butter and the mixture is smeared thickly over painful places during fever. In both Ethiopia and Tanzania it is applied to scorpion stings. In Senegal and Kenya the plant is grazed by all livestock and in Australia by camels. In Zambia however, it is not grazed by cattle. In Kenya, the leaves are chewed as a substitute for tobacco.
Pyrrolizidine alkaloids are a common constituent of the Boraginaceae and Asteraceae and the Papilionoid genus Crotalaria. These alkaloids exhibit pronounced toxic effects on the liver and lungs, whereas cytotoxic, mutagenic and carcinogenic activities have also been reported. The alkaloids retronecine, helifoline and heliotropamide have been isolated. Helifoline has been reported to show in vivo and in vitro ganglion-blocking activity. Retronecine (the amino-ethanol moiety of many pyrrolizidine alkaloids but without the ester-part) and helifoline (a 1,2-saturated retronecine analogue) are expected not to be hepatotoxic. Supinine (a pyrrolizidine alkaloid), and heliophenanthrone (a phenanthrone derivative), as well as the benzoquinones heliotropinone A and B have been isolated from the aerial parts of the plant. Both quinones have exhibited antifungal and antibacterial properties. The alkaloid heliotropamide did not show any antifungal or antibacterial activity nor did it show any radical-scavenging activity.
Cases of poisoning of sheep and goat in Sudan have been reported, and a fatal liver disease of horses in Australia has been attributed to Heliotropium ovalifolium as well. In southern Africa Heliotropium ovalifolium is suspected to be the cause of the ‘floppy trunk syndrome’, a lethal affliction in elephants. In Nigeria, the plant is considered to be poisonous, causing diarrhoea and vomiting.
Adulterations and substitutes
Many other species of Heliotropium contain pyrrolizidine alkaloids and are often used for similar purposes as Heliotropium ovalifolium.
Perennial herb, up to 90 cm tall, sometimes with woody base, much branched; young branches silvery pubescent. Leaves alternate, simple; stipules absent; petiole up to 1.5(–2) cm long; blade elliptical or obovate, up to 5.5 cm × 2.5 cm; base cuneate; apex retuse, mucronate or acute. Inflorescence a spike-like cyme, silky hairy, without bracts, with flowers arranged in two ranks, up to 4 cm long. Flowers bisexual, regular, 5-merous; calyx with almost free lobes, densely covered with antrorse hairs; corolla funnel-shaped, up to 3 mm long, pubescent outside, lobes ovate-triangular, up to 2 mm long; stamens included in corolla tube, with very short filaments; ovary superior, 4-celled. Fruit splitting into 4 nutlets, densely white hairy.
Other botanical information
Heliotropium comprises about 250 species and is distributed in tropical, subtropical and warm temperate zones of all continents. The classification suffers from the absence of a recent taxonomic revision covering Old World and New World species. The genus Heliotropium is of special interest in eastern and northern East Africa as it is associated with the initial swarming areas of migratory locusts (Locusta migratoria). Likewise butterflies are often associated with Heliotropium as they require certain pyrrolizidine alkaloids as precursor for their pheromones.
Heliotropium ovalifolium, Heliotropium ciliatum Kaplan and Heliotropium strigosum Willd. belong to the subgenus Orthostachys. Heliotropium ciliatum is found in Angola, Namibia, Botswana, Zimbabwe, Mozambique and South Africa. Its leaves are boiled and the water is drunk to cure fever and stomach-ache by Kalahari bushmen. In Namibia a decoction of roots and leaves is drunk or applied as an enema to treat pain in the legs. Oedema as a result of cardiac problems is treated by bathing with a decoction of the whole plant or as a steam bath. Heliotropium strigosum is widespread in tropical Africa and Asia as well as in Australia. It is used in Tanzania and DR Congo to treat abscesses of the breast by applying a mixture of the whole plant with butter. In Sudan the plant is thought to be effective in treating scorpion stings. In India it is used to treat snakebites, insect and scorpion stings, as a painkiller for pain in the limbs, to treat sore eyes and for healing boils, wounds and ulcers. It is eaten by camels in Sudan but not by livestock in Senegal. Heliotropium strigosum is a variable species. The inflorescence lacking bracts distinguishes it from most of the other Heliotropium species in tropical Africa.
Heliotropium supinum L. belongs to the subgenus Piptoclaina, which is closely related to subgenus Orthostachys. It is widely distributed in tropical Africa, South Africa, northern Africa, southern Europe and south-west Asia. In Namibia the pulped plant is mixed with water and applied to tumours. The pyrrolizidine alkaloids heliotrine and lasiocarpine have been isolated, and extracts have been tested as a control agent for Sclerotinia sclerotiorum, a chickpea disease, with limited success.
Growth and development
Heliotropium ovalifolium may flower throughout the year. The flowering season is long and new flowers develop apically within the cyme while mature nutlets are already present at its base. Heliotropium ovalifolium can behave as a pioneer species and stays green well into the dry season.
Heliotropium ovalifolium occurs in diverse habitats, though drier places are preferred in general.
Handling after harvest
Heliotropium plants are generally collected when fully grown and can be used either fresh or dry.
Heliotropium ovalifolium is very widespread; and there is no risk of genetic erosion.
Heliotropium alkaloids have been considered as a potential agent in chemotherapy and clinical trials have been executed. They have not been taken into pharmaceutical use as they have serious toxic (including hepatotoxic) effects attributed to the pyrrolizidine alkaloids. External application to promote wound healing and to fight infections seems less hazardous, but more research is needed. The role of Heliotropium ovalifolium in the breeding success of pest insects deserves attention.
• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 960 pp.
• Creeper, J.H., Mitchell, A.A., Jubb, T.F. & Colegate, S.M., 1999. Pyrrolizidine alkaloid poisoning of horses grazing a native heliotrope (Heliotropium ovalifolium). Australian Veterinary Journal 77(6): 401–402.
• Guntern, A.A., 2003. Phytochemical investigation of plants suspected to cause the floppy trunk syndrome of African elephants (Loxodonta africana): Heliotropium ovalifolium Forssk. (Boraginaceae) and Blumea gariepina DC. (Asteraceae). PhD thesis, Université de Lausanne, Institut de Pharmacognosie et Phytochimie, Lausanne, Switzerland. 244 pp.
• Jansen, P.C.M., 1981. Spices, condiments and medicinal plants in Ethiopia, their taxonomy and agricultural significance. Agricultural Research Reports 906. Centre for Agricultural Publishing and Documentation, Wageningen, Netherlands. 327 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Verdcourt, B., 1991. Boraginaceae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 125 pp.
• Wongsatit Chuakul, Noppamas Soonthornchareonnon & Promjit Saralamp, 1999. Heliotropium 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. 292–296.
• Boppré, M. & Fischer, O.W., 1999. Harlekinschrecken (Orthoptera: Zonocerus) – Schadinsekten der besonderen Art. (Zonocerus variegatus (Orthoptera) – a peculiar type of pest insect). Gesunde Pflanzen 51(5): 141–149.
• Dorges, B., Heucke, J. & Dance, R., 2003. The palatability of central Australian plant species to camels. Technote No 116, Agdex No 468/62, ISSN No 0158-2755. 8 pp.
• Getahun, A., 1976. Some common medicinal and poisonous plants used in Ethiopian folk medicine. Faculty of Science, Addis Ababa University, Addis Ababa, Ethiopia. 63 pp.
• Guilet, D., Guntern, A., Ioset, J.R., Queiroz, E.F., Ndjoko, K., Foggin, C.M. & Hostettmann, K., 2003. Absolute configuration of a tetrahydrophenanthrene from Heliotropium ovalifolium by LC-NMR of its Mosher esters. Journal of Natural Products 66(1): 17–20.
• Guntern, A., Ioset, J.R., Queiroz, E.F., Foggin, C.M. & Hostettmann, K., 2001. Quinones from Heliotropium ovalifolium. Phytochemistry 58(4): 631–635.
• Guntern, A., Ioset, J.R., Queiroz, E.F., Sandor, P., Foggin, C.M. & Hostettmann, K., 2003. Heliotropamide, a novel oxopyrrolidine-3-carboxamide from Heliotropium ovalifolium. Journal of Natural Products 66(12): 1550–1553.
• Martins, E.S. & Brummitt, R.K., 1990. Boraginaceae. In: Launert, E. & Pope, G.V. (Editors). Flora Zambesiaca. Volume 7, part 4. Flora Zambesiaca Managing Committee, London, United Kingdom. pp. 59–110.
Sources of illustration
• Andrews, F.W., 1956. The flowering plants of the Anglo-Egyptian Sudan, Volume 3. Buncle, Arbroath, United Kingdom. 579 pp.
Correct citation of this article:
Gurib-Fakim, A., 2006. Heliotropium ovalifolium Forssk. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, plant habit; 2, flower; 3, fruit; 4, nutlets.
Redrawn and adapted by Iskak Syamsudin