Functionally Selective Dopamine D2/D3 Receptor Agonists Comprising an Enyne Moiety
摘要:
Dopaminergics of types 1 and 2 incorporating a conjugated enyne as an atypical catechol-simulating moiety were synthesized in enantiomerically pure form and investigated for their metabolic stability. Radioligand binding studies indicated high affinity to D-2-like receptors. The test compounds were evaluated for their ability to differentially activate distinct signaling pathways. Measurement of D-2L- and D-2S-mediated [S-35]GTP gamma S incorporation in the presence of coexpressed G alpha(o) and G alpha(i) subunits showed significantly biased receptor activation for several test compounds. Thus, the 2-azaindolylcarboxamide (S)-2a exhibited substantial functional selectivity for D-2S-promoted G(o) activation over G(i) coupling. The most significant bias was determined for the triazolylalkoxy-substituted benzamide (S)-2c that displayed higher potency for G(o) activation than for G, coupling at the D-2L subtype. Functional selectivity for beta-arrestin recruitment over G(i) activation was observed for the biphenylcarboxamide (R)-1 and the 2-benzothiophenylcarboxamide (S)-2d, whereas the 2-substituted azaindole (S)-2a preferred beta-arrestin recruitment compared to G(o) coupling.
Development of a Bivalent Dopamine D2 Receptor Agonist
摘要:
Bivalent D-2 agonists may function as useful molecular probes for the discovery of novel neurological therapeutics. On the basis of our recently developed bivalent dopamine D-2 receptor antagonists of type 1, the bivalent agonist 2 was synthesized when a spacer built from 22 atoms was employed. Compared to the monovalent control compound 6 containing a capped spacer, the bis-aminoindane derivative 2 revealed substantial steepening of the competition curve, indicating a bivalent binding mode. Dimer-specific Hill slopes were not a result of varying functional properties because both the dopaminergic 2 and the monovalent control agent 6 proved to be D-2 agonists substantially inhibiting cAMP accumulation and inducing D-2 receptor internalization. Investigation of the heterobivalent ligands 8 and 9, containing an agonist and a phenylpiperazine-based antagonist pharmacophore, revealed moderate steepening of the displacement curves and antagonist to very weak partial agonist properties.
Molecular Determinants of Biased Agonism at the Dopamine D<sub>2</sub>Receptor
作者:Dietmar Weichert、Ashutosh Banerjee、Christine Hiller、Ralf C. Kling、Harald Hübner、Peter Gmeiner
DOI:10.1021/jm501889t
日期:2015.3.26
The development of biased (functionally selective) ligands Provides a formidable challenge in medicinal chemistry. In an effort to learn to design functionally selective molecular tools for the highly therapeutically relevant dopamine D-2 receptor, we synthesized a collection of agonists based on structurally distinct head groups derived from canonical or atypical dopaminergic pharmacophores. The test compounds feature a long lipophilic appendage that was shown to mediate biased signaling. By employing functional assays and molecular dynamics simulations, we could show that atypical dopamine surrogates of type 1 and 2 promote biased signaling, while ligands built from classical dopaminergic head groups (type 3 and 4) typically elicit more balanced signaling profiles. Besides this, we found a strong influence of the stereochemistry of type 4 aminotetraline-derived agonists on functional selectivity at D-2 receptors. Whereas the (S)-enantiomer behaved as a full agonist, the biased ligand (R)-4 induced poor G protein coupling but substantial beta-arrestin recruitment.