Dichapetalum cymosum

As might be expected, bacteria have been isolated from the plants that prodnce flnoroacetate, and these include an unidentified Pseudomonas sp. (Goldman 1965), a strain of Burkholderia Pseudomonas) cepacia from Dichapetalum cymosum (Meyer et al. 1990), and a strain of Morax-ella sp. (Kawasaki et al. 1981). In addition, fluoroacetate is an unusual product of microbial metabolism ... 

It is interesting to note that the toxic sodium fluoroacetate (above, p. 11) occurs in the poisonous South African plant gifblaar (Dichapetalum cymosum, PI. I). It has recently been shown that sodium fluoroacetate is a highly effective systemic insecticide, but it is difficult to say exactly how this substance will be applied on a large scale.6 There are many other insecticides containing fluorine and phosphorus, and special precautions must be taken when handling these toxic compounds. 

Fluoroacetic acid is the toxic principle of the South African plant gifblaar, Dichapetalum cymosum = Chailletia cymosa) (Dichapetalaceae). Crystals. M.p. 33° to 35°. B.p. 165° to 168°. Soluble in water and ethanol practically insoluble in most common organic solvents. 

Minnaar, P.P., McCrindle, R.I., Naude, T.W., Botha, C.J. (2000a). Investigation of biological samples for monofluoroacetate and Dichapetalum cymosum poisoning in southern Africa. Onderstepoort J. Vet. Res. 67 27-30. 

Biotransformation, especially phase I metabolic reactions, cannot be assumed to be synonymous with detoxification because some drugs (although a minority) and xenobiotics are converted to potentially toxic metabolites (e.g. parathion, fluorine-containing volatile anaesthetics) or chemically reactive intermediates that produce toxicity (e.g. paracetamol in cats). The term lethal synthesis refers to the biochemical process whereby a non-toxic substance is metabolically converted to a toxic form. The poisonous plant Dichapetalum cymosum contains monofluoroacetate which, following gastrointestinal absorption, enters the tricarboxylic acid (Krebs) cycle in which it becomes converted to monofluorocitrate. The latter compound causes toxicity in animals due to irreversible inhibition of the enzyme aconitase. The selective toxicity of flucytosine for susceptible yeasts (Cryptococcus neoformans, Candida spp.) is attributable to its conversion (deamination) to 5-fluorouracil, which is incorporated into messenger RNA. 

Fluoroacetic acid has been identifled as the toxic component of the South African plant gijblaar (Dichapetalum cymosum) [34]. Its mechanism of action is based on inhibition of the citric acid cycle, the main source of metabolic energy in all animals [35]. In this cyde, fluoroacetate can replace acetate as a substrate of aconi-tase, an enzyme complex which usually forms dtrate by addition of acetate to a-oxoglutarate. The resulting fluorocitrate is binds tightly to the enzyme, but cannot be further converted to ds-aconitate and isocitrate [36], thus inhibiting aconitase. 

Meyer, J.J.M., N. Grobbelaar, and P.L. Steyn. 1990. Fluoroacetate-metabolizing pseudomonad isolated from Dichapetalum cymosum. Appl. Environ. Microbiol. 56 2152-2155. 

Ihe diverse chemical, biological, and industrial applications of the numerous synthetic carbon-fluorine compounds are almost legendary. In 1944, Marais identified fluoroacetate in the leaves of the South African shrub Dichapetalum cymosum since then chemists and biologists continue to be intrigued by the natural occurrence, synthesis, and properties of the C-F bond. 

Huoroacetic add CHjF-COOH, a very poisonous carboxylic acid which is converted in the tricarboxylic acid cycle to fluorocitrate, a strong inhibitor of aconitase. The Thcarboxylic add cycle (see) therefore ceases to operate, with lethal results. Free F.a. occurs in the leaves of Dichapetalum cymosum, a poisonous African plant which is reponsible for cattle poisoning in South Africa. It is aira present in other plants to which it confers toxidty. [L.P. Miller and EFIemion Phytochemistry 3 (1973) 1- j nuorodtric add see Fluoroacetic add. 

Monofluoroacetate, a toxin from the poison leaf plant Dichapetalum cymosum, was isolated and analyzed on a specialty organic acid analysis column (2 = 210nm) using an aqueous 20 mM H3PO4 mobile phase [1580]. This compound waS well separated from formic, acetic, and propionic acids. Peak shapes were excellent and elution was complete in 35 min. Linearity was achieved over the range 25-... 

Sambucus nigra Combretum micranthum Dichapetalum cymosum Arbutus unedo Erica multiflora Rosmarinus spp. Psidium guajava Juniperus communis Prunus cerasus Ampelopsis hederaceae Prunus cerasus Vitis vinifera Bauhinia purpurea Citrus unshiu Litchia chinensis Sophora sp. 

Fluoroacetic acid was identified as the toxic principle of Dichapetalum cymosum, which is one of the most poisonous plants growing in South Africa (70). This acid was subsequently found in many plants belonging to several families in Africa and Australia. The seeds of D, toxicarium contain, besides a small amount of fluoroacetic acid, cofluorooleic acid as the major toxic compound (91). The presence of cu-fluoropalmitic, o>fluorocapric, and cu-fluoromyristic acids have also been reported (122). Biosynthesis of fluoroacetic acid has been proposed to occur by a nucleophilic incorporation of a fluoride ion into a C3 unit linked to... 

Marais JSC 1944 Monofluoracetic acid, the toxic principle of gifblaar Dichapetalum cymosum (Hook) Engl. Onderstepoort J Vet Sci Anim Ind 20 67-73... 

Peters, Sir Rudolph A., Mechanism of the Toxicity of the Active Constituent of Dichapetalum cymosum and Related Compounds. XVTII 113... 

Dichapetalum cymosum. Mechanism of Toxicity (Peters).XVIII... 

Fluoroacetate. Fluoroacetate 1 is the most ubiquitous fluorine-containing natural product and has been identified in over 30 plants, principally species from Africa and Australia, and also as a secondary metabolite in the bacteria Streptomyces cattleya (see below). The compoimd was first identified by Marais (4) in South Africa as the toxic principle in plants of Dichapetalum cymosum (gifblaar). The young leaves of this plant are particularly toxic in the spring when levels of fluoroacetate of up to... 

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