S-Allylcysteine

S-Allylcysteine (SAC) is an organosulfur compound that has the formula HO2CCH(NH2)CH2SCH2C\dCH2. It is the S-allylated derivative of the amino acid cysteine. As such only the L-enantiomer is significant biologically. SAC constituent of aged garlic. A number of related compounds are found in garlic, including the disulfide S-"allylmercaptocysteine" (SAMC, HO2CCH(NH2)CH2SSCH2C\dCH2) and γ-glutamyl-S-allylcysteine" (GSAC).

Allylcysteine is of interest for its potential medicinal properties. and as a chemopreventive.