The need for selective ligands acting at neuropeptides receptors constitutes an important challenge for medicinal chemists. Starting from the structures of the endogenous ligand, several studies highlighted the specific role played by an arginine residue (neuropeptide FF, neuropeptide Y, thrombin). In addition, substituted arginine derivatives have been described as potent ligands of these receptors (Scheme 1). 1., 2. and 3. ... Proline is a unique natural α-aminoacid ...
