ZJ43 (723331-20-2) is potent inhibitor of glutamate carboxypeptidases II (Ki = 0.8 nM) and III (Ki = 23 nM).1?It potently (IC50?= 2.4 nM) inhibited the ability of glutamate carboxypeptidase II to hydrolyze the neurotransmitter N-acetylaspartylglutamate (NAAG) resulting in an increase in synaptic levels of group II mGluRs. Peripherally administered ZJ43 increased the activation of mGluR3 by NAAG released from peripheral sensory neurites resulting in analgesia.2,3?ZJ43 has also shown efficacy in other inflammatory pain models.4,5