Gilbert Bergé

New trisubstituted 1,2,4-triazole derivatives as potent ghrelin receptor antagonists. 3. Synthesis and pharmacological in vitro and in vivo evaluations.

Ghrelin receptor ligands based on trisubstituted 1,2,4-triazole structure were synthesized and evaluated for their in vitro binding and biological activity. In this study, we explored the replacement of the alpha-aminoisobutyryl moiety by aromatic or heteroaromatic groups. Compounds 5 and 34 acted as potent in vivo antagonists of hexarelin-stimulated food intake. These two compounds did not stimulate growth hormone secretion in rodents and did not antagonize growth hormone secretion induced by hexarelin.

Activation of the ghrelin receptor is described by a privileged collective motion: a model for constitutive and agonist-induced activation of a sub-class A G-protein coupled receptor (GPCR).

Three homology models of the human ghrelin receptor (GHS-R1a) have been generated from the available X-ray structures of rhodopsin (RHO model), opsin (OPS model) and beta-2 adrenergic receptor (B2 model). The latter was used as a starting point for combined molecular dynamics simulation (MDS) and full atom normal modes analysis (NMA). A low-frequency normal mode (mode 16) perfectly reproduced the intracellular motions observed between B2 and RHO models; in the opposite direction along the same mode, the generated structures are closer to the OPS model, suggesting a direct link with GHS-R1a activation. This was in agreement with motions of the seven transmembranous segments, increase of the solvent accessibility of the 140-ERY-142 sequence, and flip of the Trp276 (C WLP) residue, some features related to GPCRs activation. According to our model, His280 was proposed to stabilize Trp276 in the active state; this was verified by site-directed mutagenesis and biochemical characterization of the resulting H280A and H280S mutants, which were fully functional but sharing an important decrease of their basal activities. Docking performed with short ghrelin derivatives Gly-Ser-Ser ([octa])-Phe-NH (2) and Gly-Ser-Ser ([octa])-Phe-Leu-NH (2) allowed the identification of a robust position of these peptides in the active site of the receptor. This model was refined by MDS and validated by docking experiments performed on a set of 55 ghrelin receptor ligands based on the 1,2,4- triazole scaffold. Finally, NMA performed on the obtained peptide-receptor complex suggested stabilization of the Trp276 residue and of the whole receptor in the active state, preventing the motion observed along mode 16 computed for the unbound receptor. Our results show that NMA offers a powerful approach to study the conformational diversity and the activation mechanism of GPCRs.

Design, synthesis, and biological evaluation of 1,5-benzothiazepine-4-one derivatives targeting factor VIIa/tissue factor

The 1,5-benzothiazepine-4-one scaffold was earlier shown to provide efficient protease inhibitors. In this contribution, we describe its use in the design of factor VIIa/tissue factor inhibitors. A series containing a scaffold non-substituted on its aryl part led to compound 20 with an IC(50) of 2.16 microM. Following molecular modelling studies of this compound, a second series was prepared, which necessitated the synthesis of protected 7- or 8-substituted 1,5-benzothiazepine-4-one derivatives.

Novel nonapeptide acein targets the angiotensin‐converting enzyme and induces dopamine release

Using an in‐house bioinformatics programme, we identified and synthesized a novel nonapeptide, H‐Pro‐Pro‐Thr‐Thr‐Thr‐Lys‐Phe‐Ala‐Ala‐OH. Here, we have studied its biological activity, in vitro and in vivo, and have identified its target in the brain.

The novel nonapeptide acein targets angiotensin converting enzyme in the brain and induces dopamine release

Using an in‐house bioinformatics programme, we identified and synthesized a novel nonapeptide, H‐Pro‐Pro‐Thr‐Thr‐Thr‐Lys‐Phe‐Ala‐Ala‐OH. Here, we have studied its biological activity, in vitro and in vivo, and have identified its target in the brain.

Synthesis and in Vivo pharmacological profile of dimeric HOE 140 bradykinin antagonists

Muriel Amblard, Isabelle Daffix, Gilbert Berge, Pierre Dodey, Didier Pruneau, Jean-Luc Paquet, Pierre Belichard, Jean-Michel Luccarini and Jean Martineza Laboratoire des Aminoacides Peptides et Proteines (LAPP), ESA CNRS 5075, Universites de Montpellier I et II, Faculte de Pharmacie, 15 Av. C. Flahault, 34060 Montpellier, Cedex, France. Laboratoires de Recherche FOURNIER, Route de Dijon, 21100 Daix, France