Fruit kernels, cyanide

Cyanide in trace amounts is found in a large number of plants, mainly in the form of substituted glycosides. Affected plants include grasses, fruit kernels, pulses, linseed and cassava. 

There are also natural products that contain cyanide, for example the plant cassava (see pp. 255-6) and various fruit kernels such as almonds, apricots, and apples. Oil of bitter almonds, which is used in cooking, contains enough cyanide to be lethal, and people have committed suicide by drinking it. 

Hydrogen Cyanide and Its Salts. Hydrogen cyanide, HCN (structural formula H—-Ce==N I), is a gas which dissolves in water and acts as a very weak acid. It is made by treating a cyanide, such as potassium cyanide, KCN, with sulfuric acid, and is used as a fumigant and rat poison. It smells like bitter almonds and crushed fruit kernels, which in fact owe their odor to it. Hydrogen cyanide and its salts are very poisonous. 

Intestinal microflora are capable of impacting xenobiotic metabolism by causing enterohepatic circulation and delayed excretion and by catalyzing many of the reactions that also occur as a result of detoxication and bioactivation reactions by phase I and II enzymes. The carbohydrate amygdalin, which contains a cyanide substituent, is found in the kernels of various fruits including plum, cherry, peach, and apricot as well as in almonds. Hydrolysis by the [f-glucosidases in intestinal bacteria yields reactive intermediates capable of releasing cyanide. 

Hydrogen cyanide is widely used in industry in the manufacture of plastics and nitrites and may also be produced by burning polyurethane foam. It is also found in very small quantities in the kernels of some fruits. It may be ingested or inhaled accidentally or deliberately. It may also form explosive mixtures. All cyanides are reversible cytochrome oxidase inhibitors, which prevent cellular respiration. 

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