Antagonism of NMDA receptors by butanesulfonyl-homospermine guanidine and neuroprotective effects in in vitro and in vivo

► Polyamine derivative, BsHSPMG inhibited strongly NMDA receptor currents. ► BsHSPMG acts deeply into the channel pore of NMDA receptors containing the intracellular regions. ► Cellular toxicity of BsHSPMG was approximately 2-fold weaker than that of TsHSPMG, and 40-fold weaker than that of memantine. ► Administration of BsHSPMG exhibited neuroprotective effect on mouse brain ischemia.