Cusack, Bernadette

The structure-activity relationship studies of neurotensin and its analogs have revealed that i) the C-terminal hexapeptide NT (8-13) (H-ArgB­ Arg9-Pro1o_Tyr1LIIe12-Leu13.QH) is equipotent to or more potent than the native NT(1-13) and retains all the intrinsic biological properties of neurotensin, ii) the N-terminal peptide fragment up to NT(1-7) does not significantly contribute to the binding potency, iii) Pro1o that can form a reverse-turn conformation is required, iv) an aromatic amino acid is important at Tyr11 position, v) the lipophilic side chain of Leu 13 is also crucial to the biological activities, and, vi) L-form amino acids are essential at critical positions for the binding potency. In addition to many peptidic neurotensin analogs, highly potent, orally active, and selective non-peptidic analogs as antagonists of NT receptors, which have long lasting effects and the ability to cross the blood­ brain barrier (e. g. SR 142948 A and SR 48692), have been discovered.