Synthesis of oxadiazolidinedione derivatives as quisqualic acid analogues and their evaluation at a quisqualate-sensitized site in the rat hippocampus

The ability of quisqualic acid (1) to sensitize neurons to depolarization by omega-phosphono alpha-amino acid analogues of excitatory Amino acids is a highly specific phenomenon and is termed the QUIS effect. In an attempt to elucidate the structure-activity relationships for this sensitization, analogues 2-6 of quisqualic acid have been synthesized. Compounds 4, 5, and 6 showed no quisqualate sensitization with respect to L-2-amino-6-phosphonohexanoic acid (L-AP6), while compounds 2 and 3 were 1/10 and 1/1000, respectively, as active as quisqualic acid in sensitizing neurons toward L-AP6.