Prota 11(1): Medicinal plants/Plantes médicinales 1
Prodr. 10: 148 (1846).
2n = 24
Cynoglossum geometricum Baker & C.H.Wright (1905).
Origin and geographic distribution
Cynoglossum coeruleum is fairly widespread in Central, East and southern Africa.
In Kenya the vapour of crushed leaves of Cynoglossum coeruleum is inhaled to treat fever and influenza and crushed leaves are rubbed on scorpion sting wounds. A decoction of the leaves is drunk during delivery for quick removal of the placenta. A decoction made from pounded and soaked roots is drunk by pregnant women to relieve abdominal pain. In southern Africa the crushed plants are applied to wounds as a plaster and the whole plant is used as a medicine for colic. In DR Congo it is used as a vermifuge specifically against tapeworm. In Kenya it is reportedly grazed by livestock.
Pyrrolizidine alkaloids are common constituents of the Boraginaceae and Asteraceae and the Papilionoid genus Crotalaria. They are derived from amino acids including ornithine. Many pyrrolizidine alkaloids have pronounced hepatic toxicity, but the lungs and other organs may be affected as well. Mutagenic and carcinogenic activities of pyrrolizidine alkaloids have been reported.
No specific analyses of the properties of Cynoglossum coeruleum are known. Several other Cynoglossum species are highly toxic for horses and cattle, mainly during the rosette stage, due to the presence of pyrrolizidine alkaloids. Two pyrrolizidine alkaloids have been recorded from another African species, Cynoglossum lanceolatum Forssk.: cynaustraline and cynaustine, and five from the Asian and American Cynoglossum amabile Stapf & J.R.Drumm.: supinine, amabiline, rinderine, echinatine and 3’-O-acetylechinatine. Cynoglossum officinale L., a native of Europe and western temperate Asia and an introduced weed in the United States, is by far the most comprehensively studied species of the genus.
Perennial, biennial or annual herb up to 120 cm tall, very densely hairy on young parts, usually with thick woody taproot. Leaves alternate, simple and entire; stipules absent; petiole 2–10 cm long in basal leaves, upper leaves sessile; blade narrowly ovate, elliptical-oblong, linear-oblong or oblanceolate, basal ones 8–21(–30) cm × 1–6 cm, rough with short adpressed hairs from white cystolith dots, apex acute. Inflorescence an axillary or terminal scorpioid cyme, simple, dichasial or trifid, without bracts. Flowers bisexual, regular, 5-merous; corolla blue or pinkish mauve, tube c. 2 mm long. Fruit consisting of 4 compressed ovoid nutlets, (2.5–)3.5–4 mm long, reddish, covered all over by barbed hairs.
Cynoglossum comprises about 50 species, and has a worldwide distribution. Cynoglossum coeruleum is variable and several subspecies are distinguished. Intermediates between Cynoglossum coeruleum and Cynoglossum lanceolatum occur, making a distinction between species complicated. Cynoglossum lanceolatum is used in Ethiopia as a febrifuge and leaves are added to soup in Nigeria. In Vietnam, it is considered diuretic. Cynoglossum monophlebium Baker is an endemic of Madagascar and is used as an antirheumatic. Cynoglossum amabile has been introduced in East Africa as an ornamental and has become naturalized in parts of Tanzania. It is used in traditional Chinese medicine to treat cough, scrofula and to stop bleeding of wounds.
Cynoglossum coeruleum occurs in a wide variety of habitats such as (overgrazed) grassland, bushland, evergreen forest and as a weed in fields at 750–3150(–3650) m altitude.
Genetic resources and breeding
Germplasm collections of Cynoglossum do not exist. This fairly widespread species of various habitats is not threatened by genetic erosion.
Little is known about the properties of Cynoglossum coeruleum. Studies of related species report interesting properties, e.g. wound healing and antibacterial activities. Research on these aspects in Africa is desirable, and might enhance the medicinal importance in the region. Improvements in the taxonomic classification are considered only possible after detailed study of the taxa in both Africa and India.
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Correct citation of this article:
Bosch, C.H., 2006. Cynoglossum coeruleum DC. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(1): Medicinal plants/Plantes médicinales 1. [CD-Rom]. PROTA, Wageningen, Netherlands.