Selective and potent GLUK5 (GluR5)-subunit containing kainate receptor antagonist (apparent KD = 402 nM); active enantiomer of UBP 296 (Cat. No. 2078). Displays ~ 260-fold selectivity over AMPA receptors. UBP 296 displays ~ 90-fold selectivity over recombinant human GLUK6- and GLUK2-containing kainate receptors, has little or no action at NMDA or group I mGlu receptors and selectively blocks kainate receptor-mediated LTP induction in rat hippocampal mossy fibres.