Screening oxime libraries by means of mass spectrometry (MS) binding assays: Identification of new highly potent inhibitors to optimized inhibitors γ-aminobutyric acid transporter 1

Abstract Generation and screening of oxime libraries by competitive MS Binding Assays represents a powerful tool for the identification of new compounds, with affinity to mGAT1, the most abundant plasma membrane bound GABA transporter in the CNS. By screening a guvacine derived oxime library, new potent inhibitors of mGAT1 had been revealed. In the present study, oxime libraries generated by reaction of a large excess of a rac -nipecotic acid derivative displaying a hydroxylamine functionality in which various aldehydes under suitable conditions, were examined for new potent inhibitors of mGAT1. The p K i values obtained of the best hits were compared with those of related compounds displaying a guvacine instead of a nipecotic acid subunit as hydrophilic moiety. Amongst the new compounds one of the most affine ligands of mGAT1 known so far (p K i  = 8.55 ± 0.04) was found.