Glucosinolates, a group of plant thioglucosides, occur naturally in many plant species. These consist of a β-thioglucose moiety, a sulfonated oxime moiety, and a variable side chain derived from an amino acid. More than 120 different side chains have been described, although glucosinolates are often divided into three groups according to the nature of their side chain: aliphatic, aromatic, and indolyl. The difference between the glucosinolates with regard to chemical properties and biological activity and the hydrolyzed products formed are largely determined by the side-chain structure.