Cyanogenesis in Higher Plants and Animals.

Lechtenberg, Matthias

Lexikonartikel (Buchbeitrag)

Zusammenfassung

Cyanogenesis describes the ability of living organisms toliberate hydrogen cyanide from stored cyanogenicglycosides, cyanogenic lipids or cyanohydrins on tissuedamage by hydrolysis and/or decomposition. It has beendescribed for over 2650 species of higher plants and someanimals. Together with plant b-glucosidases and hydroxynitrilelyases cyanogenic glycosides are the constituentpart of a preformed defence system. Today it's generallyaccepted that cyanogenic glycosides also may serve asstorage form for reduced nitrogen and sugar. Severalstudies show an endogenous in vivo turnover without liberationof HCN. Chemically, cyanogenic glycosides areglycosides of a-hydroxynitriles (cyanohydrins). In the vastmajority of all cases the sugar directly attached to theaglycone is b-D-glucose; according to this sometimes theterm cyanogenic glucoside is used in literature as acommonname which is not correct. More than 60 cyanogenicglycosides are known today. The structures are biogeneticallyrelated to only a few precursor amino acids. Biogeneticallyclosely related are some noncyanogenicglucosides of b- and c-hydroxynitriles (cyanoglucosides).Their biological function is not fully understood untiltoday. Many food plants are cyanogenic and great effortsare made to optimise detoxification. Humans are able todetoxify considerable amounts of HCN. Although acuteintoxication is rare, the daily consumption of subacuteamounts of cyanogenic glycosides leads to chronic diseases,caused by increased plasma levels of the humandetoxification products. The presence of cyanogenicglycosides in the animal kingdom appears to be restrictedto Arthropoda. Some insects, often aposematicallycoloured, either de novo synthesise cyanogenic glycosidesand/or sequester themfrom their host plants.

Details zur Publikation

Herausgeber*innen:
Buchtitel: Encyclopedia of Life Sciences (ELS)
Veröffentlichungsjahr: 2011
Verlag: John Wiley & Sons, Ltd
Sprache, in der die Publikation verfasst ist: Englisch
Link zum Volltext: http://www.els.net/WileyCDA/ElsArticle/refId-a0001921.html