Further optimization of the K-Cl cotransporter KCC2 antagonist ML077: Development of a highly selective and more potent in vitro probe

Further chemical optimization of the MLSCN/MLPCN probe ML077 (KCC2 IC50 = 537 nM) proved to be challenging as the effort was characterized by steep SAR. However, a multi-dimensional iterative parallel synthesis approach proved productive. Herein we report the discovery and SAR of an improved novel antagonist (VU0463271) of the neuronal-specific potassium-chloride cotransporter 2 (KCC2), with an IC50 of 61 nM and >100-fold selectivity versus the closely related Na-K-2Cl cotransporter 1 (NKCC1) and no activity in a larger panel of GPCRs, ion channels and transporters.

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