Cyanogen toxicity

Ernesto, M., A. P. Cardoso, D. Nicala, E. Mirione, F. Massaza, J. Cliff, M. R. Haque, and J. H. Bradbury. 2002. Persistent konzo and cyanogen toxicity from cassava in northern Mozambique. Acta Trop. 82(2)) 357-62. 

Cyenogenic Mechanism. The acute toxicity of a third class of simple nonelectrolytes can be readily rationalized in terms of a cyanogenic mechanism, involving metabolic release of cyanide. Free cyanide is highly toxic to fish with a TLm of 0.69 mg/L (93). Some examples of cyanogenic toxicants are shown in Table IV. Lactonitrile is... 

Cyanide destmction by alkaline chlorination is a widely used process. With alkaline chlorination, cyanide is first converted to cyanate with hypochlorite [7681-52-9] at a pH greater than 10. A high pH is required to prevent the formation of cyanogen chloride [506-77-4] which is toxic and may evolve in gaseous form at a lower pH. With additional hypochlorite, cyanate is then oxidized to bicarbonate, nitrogen gas, and chloride. The pH for this second stage is 7—9.5 (6). 

Cyanide compounds are classified as either simple or complex. It is usually necessary to decompose complex cyanides by an acid reflux. The cyanide is then distilled into sodium hydroxide to remove compounds that would interfere in analysis. Extreme care should be taken during the distillation as toxic hydrogen cyanide is generated. The cyanide in the alkaline distillate can then be measured potentiometricaHy with an ion-selective electrode. Alternatively, the cyanide can be determined colorimetricaHy. It is converted to cyanogen chloride by reaction with chloramine-T at pH <8. The CNCl then reacts with a pyridine barbituric acid reagent to form a red-blue dye. 

Caution Since cyanogen chloride is highly toxic, the preparation and isolaiion of the sulfonyl cyanide should be condwted in a well-ventilated hood. 

Toxic anoxia caused by damage to Carbon monoxide cyanogen, hydrogen ... 

Cyanogen bromide (Bromine cyanide) CNBr Extremely irritating and toxic vapours Contact with acids, acid fumes, water or steam can produce toxic and corrosive fumes Transparent crystals with a penetrating odour Melting point 52°C Boiling point 61 °C Vapour density 3.6 Water soluble... 

Cyanogen chloride (Chlorine cyanide) CNCI Poisonous liquid or gas Vapour highly irritating and very toxic Colourless liquid with a strong irritating smell Boiling point 1 3°C Vapour density 2.1... 

Cyanogenic glycosides are potentially toxic because they liberate hydrogen cyanide on enzyme-catalyzed or acidic hydrolysis. Give a mechanistic explanation for this behavior for the specific cases of... 

Hydrogen cyanide, a highly toxic gas, can decompose to cyanogen and hydrogen gases,... 

Nonvolatile Inhibitors. Glycosides A number of toxic constituents are known to be released by the enzymatic degradation of various glycosides. Some of the volatile components have been mentioned previously—i.e., isothiocyanates from mustard oil glycosides and hydrogen cyanide from cyanogenic glycosides. 

Cyanogenic glycosides toygdalin (or its reduced form, prunasin) and dhurrin are known to be allelopathic (3,48). Not only are these glycosides hydrolyzed to produce hydrogen cyanide, but the benzaldehyde or hydroxybenzaldehyde (produced during hydrolysis) is oxidized to benzoic acid which itself nay be toxic to several species (3, 48). 

Cyanogen bromide is an extremely toxic chemical and should be used only in a well-ventilated fume hood using the appropriate personal protective gear. The following protocol is based on the method of March et al. (1974), as recommended by Bang s Laboratories. 

In a fume hood, dissolve 1 g of cyanogen bromide in 0.5 ml of acetonitrile (highly toxic ). 

Highly toxic substances, such as cyanides, are sometimes feeding cues and stimulants for specialized insects. For example, instar larvae of the southern armyworm (Spodoptera eridania) strongly prefer cyanogenic foods, such as foliage of the lima bean, a plant with comparatively elevated cyanide content — up to 31 mg/kg in some varieties — in the form of linamurin (Brattsten et al. 1983). Feeding was stimulated in southern army worms at dietary levels up to 508 mg KCN/kg... 

The toxicity of cyanogenic plants is a problem for both domestic and wild ungulates. Poisoning of herbivorous ungulates is more prevalent under drought conditions, when these mammals become... 

Linamurin is the principal cyanogenic glycoside in cassava its toxicity is due to hydrolysis by intestinal microflora releasing free cyanide (Padmaja and Panikkar 1989). Rabbits (Oryctolagus cuniculus) fed 1.43 mg linamurin/kg BW daily (10 mg/kg BW weekly) for 24 weeks showed effects similar to those of rabbits fed 0.3 mg KCN/kg BW weekly. Specihc effects produced by linamurin and KCN included elevated lactic acid in heart, brain, and liver reduced glycogen in liver and brain and marked depletion in brain phospholipids (Padmaja and Panikkar 1989). 

---