Syanogeeniset

Syanogeeniset, or cyanogenic compounds, are a group of plant secondary metabolites capable of releasing hydrogen cyanide (HCN) when they are enzymatically hydrolyzed. They occur mainly as cyanogenic glycosides, in which a sugar moiety is bound to a cyanohydrin precursor, and as related aglycones. In intact plant tissues the enzymatic systems responsible for hydrolysis are segregated from the glycoside, but tissue damage or processing brings them into contact and triggers release of HCN.

Common cyanogenic glycosides include amygdalin, prunasin, linamarin and lotaustralin, and dhurrin. Amygdalin is found in bitter almonds and the kernels of some stone fruits (apricots, peaches, plums), prunasin occurs in seeds of many Prunus species, linamarin and lotaustralin are found in cassava and other plants, and dhurrin is characteristic of some sorghum species. Upon damage, β-glucosidases cleave the sugar portion, and the resulting cyanohydrins are unstable and release hydrogen cyanide, sometimes with the aid of hydroxynitrile lyases.

Ecologically, cyanogenic compounds serve as chemical defenses against herbivores and pathogens, contributing to plant deterrence while often being present at low, non-lethal levels in edible parts after processing. Human exposure occurs mainly through ingestion of large amounts of seeds or tissues rich in cyanogenic glycosides, or through improper processing of certain crops. Hydrogen cyanide inhibits cellular respiration and can be toxic; symptoms range from dizziness and nausea to severe poisoning in high doses.

Processing methods such as soaking, cooking, fermenting, or thorough cooking reduce cyanogenic content in many foods. Safety guidance emphasizes proper preparation of cyanogenic-containing plants, especially cassava, and awareness of potential toxicity in seeds and kernels.