Cyclic peptides are polypeptide chains with a ring structure, connected between the amino and carboxyl termini of a peptide. Many cyclic peptides have been discovered in nature, and many other types of cyclic peptides have been synthesized in the laboratory. Due to their structural specificity, cyclic peptides are a conformationally stable class of compounds among peptide molecules, with high selectivity for receptors, high metabolic stability, and high oral availability. Cyclic peptides generally have a large surface area and can better bind to the surface of target proteins, which can be used in developing protein-protein interaction (PPI) drugs. Cyclic peptides also have a wide range of biological activities, such as antibacterial, antitumor, antifungal, antiviral, and anti-inflammatory bioactivity.

The TargetMol Cyclic Peptide Library collects 80 cyclic peptide molecules that can be used for drug development and related mechanistic studies.