Isothiocyanates (ITCs) are a group of molecules formed as a result of glucosinolate hydrolysis. See: Glucosinolates.
Isothiocyanates are potent compounds for decreasing cancer risk. Sulphoraphane, an ITC, is considered one of the 40 most promising anticarcinogens by the National Cancer Institute; it is found primarily in broccoli. Isothiocyanates may affect thyroid function through interferences to thyroid hormone synthesis.
The enzymatic activity that produces isothiocyanates is more likely to occur with longer, high temperature storage and at a neutral pH. Cooking, however, reduces overall ITC content as they are unstable. Air drying the leaves of glucosinolate-containing plants also increases presence of ITCs.