The
glucosinolates are a class of
organic compounds that contain
sulfur and
nitrogen and are derived from
glucose and an amino acid. They occur as
secondary metabolites of almost all
plants of the
order Brassicales (including the
family Brassicaceae,
Capparidaceae and
Caricaceae), but also in the genus
Drypetes (
family Euphorbiaceae)
[2].
Plants use substances derived from glucosinolates as natural pesticides, and as defense against herbivores; these substances are also responsible for the bitter or sharp taste of many common foods such as mustard, radish, horseradish, maca, cress, cabbage, Brussels sprouts, kohlrabi, kale, cauliflower, broccoli, turnip, swede (rutabaga), and rapeseed.
Glucosinolates are water-soluble anions and belong to the glucosides. Every glucosinolate contains a central carbon atom, which is bound via a sulfur atom to the thioglucose group (making a sulfated ketoxime) and via a nitrogen atom to a sulfate group. In addition, the central carbon is bound to a side group; different glucosinolates have different side groups, and it is variation in the side group that is responsible for the variation in the biological activities of these plant compounds.
About 120 different glucosinolates are known to occur naturally in plants. They are synthesized from certain amino acids So-called aliphatic glucosinolates derived from mainly methionine, but also alanine, leucine, or valine. (Most glucosinolates are actually derived from chain-elongated homologues of these amino acids, e.g., the cancer-preventing glucoraphanin derived from dihomomethionine, which is methionine chain-elongated twice). Aromatic glucosinolates include Indolic glucosinolates such as glucobrassicin derived from tryptophan and other ones from phenylalanine, its chain-elongated homologue homophenylalanine, and sinalbin derived from tyrosine.
