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DICHAPETALACEAE

The family comprises about 154 species in 3 genera, and occurs in tropical regions. The largest genus is Dichapetalum Thouin which accounts for about 124 species, mainly in Africa. Several are recognised as being extremely poisonous (Mabberley 1987). The plants were formerly classified in the family Chailettiaceae.

A skin irritant effect from handling a species of Dichapetalum has been reported.

Dichapetalum braunii Engl. & K. Krause

Watt & Breyer-Brandwijk (1962) noted that in Tanganyika [now Tanzania], the powdered leaf is applied topically to sores despite the fact that the plant is regarded as being very poisonous.

Dichapetalum cymosum Engl.

(syn. Chailletia cymosa Hook.)

Gifblaar

According to Watt & Breyer-Brandwijk (1962), the Northern Sotho maintain that handling the very young leaf causes a tingling and burning sensation of the skin, an effect not found with the old leaf. Whether this is related to the reported presence of monofluoroacetate in this and other Dichapetalum species (Vickery & Vickery 1975) is not clear. Inadvertent contact with sodium monofluoroacetate dust has been reported to produce a tingling sensation around the corners of the mouth and in the nasal passages (Grant 1974).

VETERINARY ASPECTS

Several species, including Dichapetalum cymosum, D. macrocarpum Engl., D. mossambicense Engl., D. stuhlmannii Engl., D. toxicarium Baillon, and D. venenatum Engl. & Gilg contain monofluoroacetate in a form that is easily leached from the leaves (Vickery & Vickery 1975, Watt & Breyer-Brandwijk 1962). This material has been found to be the toxic factor responsible for livestock losses in southern Africa following ingestion of Dichapetalum species. The condition is known as dichapetalosis. Other monofluoroacetate-containing plants that have been reported to be toxic to grazing livestock include Acacia georginae Bailey (fam. Leguminosae) in north-eastern Queensland, Australia (Oelrichs & McEwan 1961), Gastrolobium R. Br. species (fam. Leguminosae) in western Australia (Twigg et al. 1996), Spondianthus preussii Engl. var preussi (fam. Euphorbiaceae) in tropical east Africa (Sere et al. 1982), and Palicourea marcgravii A. St. Hil. (syn. Psychotria marcgravii Sprengel) in Brazil (De Moraes-Moreau et al. 1995, Kemmerling 1996).

Monofluoroacetate ingestion interferes with the tricarboxylic acid cycle (see, for example, Liébecq & Peters 1949, Omara & Sisodia 1990).

References

• De Moraes-Moreau RL, Haraguchi M, Morita H and Palermo-Neto J (1995) Chemical and biological demonstration of the presence of monofluoroacetate in the leaves of Palicourea marcgravii St. Hil. Brazilian Journal of Medical and Biological Research 28(6): 685-692
• Grant WM (1974) Toxicology of the Eye. 2nd edn. Springfield, Ill.: CC Thomas.
• Kemmerling W (1996) Toxicity of Palicourea marcgravii: combined effects of fluoroacetate, N-methyltyramine and 2-methyltetrahydro-beta-carboline. Zeitschrift für Naturforschung. Section C. Biosciences 51(1-2): 59-64
• Liébecq C, Peters RA (1949) The toxicity of fluoroacetate and the tricarboxylic acid cycle. Biochimica et Biophysica Acta 3: 215-230 [doi] [doi-2] [pmid]
• Mabberley DJ (1987) The Plant-Book. A portable dictionary of the higher plants. Cambridge: Cambridge University Press.
• Oelrichs PB and McEwan T (1961) Isolation of the toxic principle in Acacia georginae. Nature, London 190: 808-809
• Omara F and Sisodia CS (1990) Evaluation of potential antidotes for sodium fluoroacetate in mice. Veterinary and Human Toxicology 32(5): 427-431
• Sere A, Kamgue RT, Assi LA and Ba AC (1982) [Spondianthus preussii Engl. var. preussi, a toxic plant to African cattle. Extraction and assay of monofluoroacetic acid, an active principle]. Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux 35(1): 73-82
• Twigg LE, King DR, Bowen LH, Wright GR and Eason CT (1996) Fluoroacetate content of some species of the toxic Australian plant genus, Gastrolobium, and its environmental persistence. Natural Toxins 4(3): 122-127
• Vickery B and Vickery ML (1975) The synthesis and defluorination of monofluoroacetate in some Dichapetalum species. Phytochemistry 14(2): 423-427
• Watt JM and Breyer-Brandwijk MG (1962) The Medicinal and Poisonous Plants of Southern and Eastern Africa. Being an account of their medicinal and other uses, chemical composition, pharmacological effects and toxicology in man and animal. 2nd edn. Edinburgh: E & S Livingstone

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