Diketopiperazine

Diketopiperazines (DKP) are a class of cyclic organic compounds that result from peptide bonds between two amino acids to form a lactam. They are combinations of ketones and the compound piperazine. A diketopiperazine was the first peptide to have its complete three-dimensional structure described, in work undertaken at Caltech by Robert Corey in the 1930s. Corey studied the cyclic anhydride of the dipeptide glycyl glycine.

Some diketopiperazines are considered carcinogenic.