Structural studies on model peptides have led to a good understanding of the rules behind the formation and stability of regular beta-hairpins. To test their applicability to the successful design of irregular beta-hairpins with long loops and/or beta-bulges at the strands, we mimicked loop 3 of vammin, a 4:6 beta-hairpin with a non-Gly beta-bulge. The most stabilising cross-strand pairs, disulfide bonds or/and TrpTrp pairs, were incorporated at non-hydrogen-bonded sites in peptides spanning the 69-80 region of vammin. According to NMR data, these modified peptides adopt beta-hairpin conformations as intended by design. The Trp-containing peptides reproduce even the unusual positive phi angle for the Gln residue, with the indole rings in the preferred edge-to-face orientation. For the first time the beta-hairpin-stabilising capacities of a disulfide bond and a TrpTrp pair are compared in the same model system. We found that the contribution to stability of the noncovalent indole-indole interaction is larger than that of the covalent disulfide bond, and that their combination gives rise to an even more stable beta-hairpin.

Abstract. TRPM8 ion channels, the primary cold sensors in humans, are activated by innocuous cooling (< 28 ºC) and cooling compounds (menthol, icilin), and are implicated in sensing unpleasant cold stimuli, as well as in mammalian thermoregulation. Over-expression of these thermoregulators in prostate cancer and in other life-threatening tumors, along with their contribution to an increasing number of pathological conditions, opens a plethora of medicinal chemistry opportunities to develop receptor modulators. This Perspective seeks to compile current known modulators for this ion channel, since both agonists and antagonists may be useful for the treatment of most TRPM8-mediated pathologies. We primarily focus on SAR data for the different families of compounds and the pharmacological properties of the most promising ligands. Furthermore, we also address the knowledge about the channel structure, although still in its infancy, and the role of the TRPM8 protein signalplex to channel function and dysfunction. We finally outline the potential future prospects of the challenging TRPM8 drug discovery field.

Compound 31 is a novel, potent and selective α7 nAChR PAM, displaying antioxidant and analgesic activities. The 1,3-diphenylpropan-1-one scaffold could be the base toward more advanced type I PAMs for the treatment of nAChR-mediated diseases.

No abstract

aThe design, synthesis, conformational studies and binding affinity for VEGF receptors of a collection of linear and cyclic peptide analogues of the N-terminal α-helix fragments 13-25 of VEGF and 1-13 of Vammin are described. Linear 13(14)-mer peptides were designed with the help of an AGADIR algorithm and prepared following peptide solid-phase synthetic protocols. Cyclic peptide derivatives were prepared on-resin from linear precursors with conveniently located Glu and Lys residues, by the formation of amide linkages. Conformational analysis, CD and NMR, showed that most synthesized peptides have a clear tendency to be structured as α-helices in solution. Some of the peptides were able to bind a VEGFR-1 receptor with moderate affinity. In addition to the described key residues (Phe17, Tyr21 and Tyr25), Val14 and Val20 seem to be relevant for affinity.

No abstract

The mammalian transient receptor potential melastatin channel 8 (TRPM8), highly expressed in trigeminal and dorsal root ganglia, mediates the cooling sensation and plays an important role in the cold hypersensitivity characteristic of some types of neuropathic pain, as well as in cancer. Consequently, the identification of selective and potent ligands for TRPM8 is of great interest. Here, a series of compounds, having a β-lactam central scaffold, were prepared to explore the pharmacophore requirements for TRPM8 modulation. Structure-activity studies indicate that the minimal requirements for potent β-lactam-based TRPM8 blockers are hydrophobic groups (benzyl preferentially or tBu) on R1, R2, R3 and R5 and a short N-alkyl chain (≤3 carbons). The best compounds in the focused library (41 and 45) showed IC50 values of 46 nM and 83 nM, respectively, in electrophysiology assays. These compounds selectively blocked all modalities of TRPM8 activation, i.e. menthol, voltage, and temperature. Molecular modelling studies using a homology model of TRPM8 identified two putative binding sites, involving networks of hydrophobic interactions, and suggesting a negative allosteric modulation through the stabilization of the closed state. Thus, these β-lactams provide a novel pharmacophore scaffold to evolve TRPM8 allosteric modulators to treat TRPM8 channel dysfunction.

[reaction: see text] The base-promoted cyclization of optically pure N-(p-methoxybenzyl)-N-(2-chloro)propionyl amino acid derivatives resulted in a diastereo- and enantioselective approach to valuable 1,3,4,4-tetrasubstituted beta-lactams. The stereochemical outcome of the reaction is exclusively governed by the configuration of the N-(2-chloro)propionyl moiety.