Diketopiperazine

[3][4] Due to their appearance in biologically active natural products, medicinal chemists have been inspired to use DKPs to circumvent the poor physical and metabolic properties of peptides in the course of drug discovery.

DKPs are synthesized by a wide range of organisms, including bacteria, fungi, more complex marine microorganisms, and even mammals.

[1] DKPs have been shown to inhibit the activities of bacteria, fungi, viruses, and potentially protozoa, as well as exhibit antitumor and antiprion properties.

The molecule glionitrin, for instance, proved to be very effective against methicillin-resistant Staphylococcus aureus (MRSA), in addition to four different human cancer cell lines in vitro.

[1] Despite the great potential for diversity in this class of molecules, natural DPKs containing proline are significantly overrepresented among those known to be biologically active.