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Isothiocyanate is the chemical group -N=C=S, formed by substituting sulfur for oxygen in the isocyanate group. Allyl isothiocyanate is also called mustard oil.
Reactions
Isothiocyanates act as electrophiles with the carbon atom as the electrophilic center. This is demonstrated by the reaction of the acetophenone enolate with phenyl isothiocyanate. In this one-pot synthesis the ultimate reaction product is a Thiazolidine. This reaction is stereoselective with the formation of the Z-isomer only as evidenced by the Nuclear Overhauser effect in the proton NMR spectrum.
How they are found in nature
Isothiocyanates are largely found locked in the form of 'glucosinolates' and are found largely in cruciferous vegetables such as brocolli and Brussel's sprouts, as well as in wasabi (domestic Japanese horseradish) and watercress. Such plants contain an enzyme termed 'myrosinase' which can induce a rearrangement of the glucosinolates leading to the generation of the free isothiocyanate.
Biological Activity
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*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.
See also
References
- Improved approaches in the synthesis of new 2-(1, 3-thiazolidin-2Z-ylidene)acetophenones M. Carmen Ortega-Alfaro, José G. López-Cortés, Hiram Rangel Sánchez, Rubén A. Toscano, Guillermo Penieres Carrillo, and Cecilio Álvarez-Toledano Arkivoc (EJ-1528C) pp 356-365 2005 Online article
"Isothiocyanate"