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Synthesis and pharmacological evaluation of bivalent tethered ligands to target the mGlu heterodimeric receptor results in a compound with mGlu homodimer selectivity

Authors

Fulton MG Mark G , Loch MT Matthew T , Rodriguez AL Alice L , Lin X Xin , Javitch JA Jonathan A , Conn PJ P Jeffrey , Niswender CM Colleen M , Lindsley CW Craig W .
Bioorganic & medicinal chemistry letters. 2020 4 25; 30(13).
127212

Abstract

This Letter details our ongoing efforts to develop selective positive allosteric modulators (PAMs) of the mGlu heterodimeric receptor that exists in the CNS and may represent a novel drug target to modulate the glutamatergic system. As multiple hit-to-lead campaigns from HTS hits failed to produce selective small molecule mGlu heterodimer PAMs, we were inspired by the work of Portoghese to synthesize and evaluate a set of nine bivalent tethered ligands (possessing an mGlu PAM at one terminus and an mGlu PAM at the other). Utilizing G protein-Inwardly Rectifying Potassium (GIRK) channel functional assays, we found that the tethered ligands displayed PAM activity in a cell line co-expressing both mGlu and mGlu but also in cells expressing mGlu or mGlu alone. In a CODA-RET assay, one of the tethered ligands potentiated mGlu heterodimers; however, another compound displayed 75-fold preference for the mGlu homodimer over heterodimeric mGlu or homomeric mGlu. This work highlights the development of mGlu receptor PAMs with homodimer/heterodimer preference and expands the potential for PAMs as tethered ligands beyond the more classical antagonists and NAMs.

Tags: 2020