Conformational Rigidity Versus Flexibility in a Novel Peptidic Neurokinin A Receptor Antagonist

Neurokinin A receptor antagonists have been proposed as a new class of drugs for several applications in humans (asthama, intestinal motility, etc.). The rational design, synthesis, structural characterization and biological activity evaluation of a new potent, highly selective, long-lasting, peptide-based receptor antagonist are reported. The structure–activity relationship indicates that the conformational rigidity determines potency, specificity and especially the long life of the molecule in the living body. MEN 10627 is the prototype of a new class of cyclic, peptide-based, neurokinin A receptor antagonists and it is a suitable candidate for clinical testing in humans.