Nitrogen-Containing Compounds

Nitrogen-containing compounds include three main metabolic classes: alkaloids, cyanogenic glucosides and glucosinolates. Alkaloids show the most diversified structures among the secondary metabolites. This results in high chemotaxonomical values at low taxonomic levels. They are classified by combining precursor sources (amino acid or not) with the occurrence of nitrogen within heterocycle or chain (in the final product). This coupling results in three alkaloid classes including true alkaloids, protoalkaloids and pseudoalkaloids. Cyanogenic Glucosides are based on hydroxnitrile structures characterized by the occurrence of cyanide (CN) stabilized by a glycosyl group. Their hydrolysis (cyanogenesis) provides toxic hydrogen cyanide (H-CN) playing key defensive role against pathogen and herbivorous attacks. Glucosinolates contain nitrogen, glucosyl and sulfur. Their hydrolysis provides isothiocyanate (toxic against harmful biological organisms). Glucosinolates show limited botanical distribution and are particularly abundant in Brassicaceae and some other plant families.