Isothiocyanate is the chemical group -N=C=S, formed by substituting sulfur for oxygen in the isocyanate group. Allyl isothiocyanate is a chemical compound found in mustard oil that is responsible for its pungency. It is used for amino acid sequencing in Edman degradation.
Isothiocyanates generally act as electrophiles with the carbon atom as the electrophilic center.
Isothiocyanates, such as phenethyl isothiocyanate (PEITC) and sulforaphane, have been shown to inhibit carcinogenesis and tumorigensis and as such are useful chemopreventive agents against the development and proliferation of cancers. They work on a variety of levels. Most notably, they have been shown to inhibit carcinogenesis through inhibition of cytochrome P450 enzymes, which oxidise compounds such as benzo[a]pyrene and other polycyclic aromatic hydrocarbons (PAHs)into more polar epoxy-diols which can then cause mutation and induce cancer development. Phenethyl isothiocyanate (PEITC) has been shown to induce apoptosis in certain cancer cell lines, and in some cases, is even able to induce apoptosis in cells that are resistant to some currently used chemotherapeutic drugs. For example, in drug resistant leukemia cells which produce the powerful apoptosis inhibitor protein BCl-2.