Mercapturic acids are condensation products formed from the coupling of cysteine with aromatic compounds. They are formed as conjugates in the liver and are excreted in the urine.
Glutathione adducts lose glutamate and glycine portions, and are acetylated to form mercapturic acids, which are excreted.
Levels of mercapturic acids in urine may be used as an indicator of exposure to, e.g., ethylene dibromide, acrylamide, and terbuthylazine.