Sing-Yuen Sit

Novel dihydropyrazine analogues as NPY antagonists

The dihydropyridine is currently one of the lead compounds in the neuropeptide-Y(1) (NPY-Y(1)) receptor antagonist program. Compound is a selective, high affinity ligand at the NPY-Y(1) receptors (IC(50)=4.2 nM) in SK-N-MC cells. To further expand the SAR study surrounding this dihydropyridine core structure we succeeded in synthesizing an analogous series of dihydropyrazine derivatives. This structural modification yielded compounds substantially different from the parent molecules in terms of molecular polarization and electron distribution while the overall molecular structure was generally preserved. This altered property should therefore provide us with additional SAR information on the optimal binding requirement with NPY receptors.

N-Benzylated benzimidazol-2-one derivatives: activators of large-conductance Ca2+-dependent K+ channels

Abstract A series of benzimidazol-2-ones structurally homologous to the known maxi-K opener NS-004 (2) were synthesized and evaluated by electrophysiological techniques as openers of the cloned maxi-K channel m Slo expressed in Xenopus laevis oocytes. The structure-activity relationships reveal tolerance in the topological relationship between the heterocycle and the phenol hydroxy and indicate the importance of an electron withdrawing substituent on the heterocycle for expression of maxi-K opening properties. The most efficacious activators of this channel were the 5-Cl derivative 4f and the 5-NO 2 analogue 4i .

3-Hydroxy-quinolin-2-ones: Inhibitors of [3H]-glycine binding to the site associated with the NMDA receptor

Abstract A series of substituted 3-hydroxy-quinolin-2-one derivatives 6 was synthesized and evaluated as inhibitors of [3H]-glycine and [3H]-AMPA binding to rat cortical membranes. These compounds were generally found to be more potent ligands for the NMDA-associated glycine binding site than the AMPA receptor. Affinity for the glycine site was found to be influenced by both the electronic and steric properties associated with the C-4 substitutent and the nature and pattern of substitution of the aromatic ring. The most active compound in this series, 6y, displaces [3H]-glycine with an IC50 of 29 nM.