Phenethyl isothiocyanate (PEITC) is a naturally occurring isothiocyanate whose precursor, gluconasturtiin is found in some cruciferous vegetables,[1] especially watercress.

PEITC has been studied for its potential for chemoprevention of cancers,[2][3] such as prostate cancer.

[4] In terms of biosynthesis, PEITC is produced from gluconasturtiin by the action of the enzyme myrosinase.