Recent progress of synthetic studies to peptide and peptidomimetic cyclization

A large number of cyclic peptides, which exhibit a range of biological activities, have been found in nature. The reason of cyclic peptides that attracted world wide attention and made them extensively studied, is their enhanced metabolic stabilities, biological specificities, bioavailability, and conformational constrained structural feature, which make them important leads for drug discovery, and as actual drugs. Many cyclic peptides show very promising biological activities, including anticancer, antibacterial, antiviral, antifungal, anti-inflammatory, and anti-clotting or anti-atherogenic properties. Peptide cyclization becomes an effective and commonly employed strategy for peptide modifications. During the past several decades, great efforts have been made to develop more efficient methods for the synthesis of cyclic peptides and peptidomimetics. This review will be focused on the major progress of the novel recently developed peptide cyclization approaches and the profitable applications since 2002.