Part one. Synthesis of phosphorus-containing amino acid analogues derived from trans-4-hydroxyproline and the study of their bioactivity in the glutamate excitatory neurotransmitter system. Part two. Synthesis, structural modifications and in vitro pharma

I. Three target analogues were prepared starting from the commercially available trans-4-hydroxyproline. Following amine and carboxylic acid group protection, hydroxy proline was phosphorylated at the 4-hydroxy position. Deprotection of the amine and carboxylic acid group afforded the 4-phosphate diester target compound. A selective dealkylation at the phosphate diester group provided the mono-phosphate acid. A non-selective dealkylation afforded the diacid phosphate analogue. The in vitro activity of these three analogues at the Na-dependent synaptosomal and Cl-dependent astroglial transporters and NMDA, AMPA, and kainate receptors was minimal. Other possible sites (glutamine synthetase and the AP4 receptor) of the glutamate system remain to be tested.; II. A panel of quinoline-2,4-dicarboxylic acids (QDC's) were synthesized by a Doebner von Miller-type reaction sequence and tested as inhibitors of the glutamate vesicular transporter (GVT) protein isolated from Sprague-Dawley Rats. Structure-activity relationships and kinetic properties of select QDC analogues were evaluated.; The QDC analogues, based on kynurenate derivatives and azo dye analogues, revealed a key lipophilic moiety. Aromatic substituents demonstrated optimal sterics and rigidity versus aliphatic functional groups to aid in the structural position of the hydrophobic binding pocket. The azo functional group exhibited in azo dye analogues were incorporated into the QDC template and revealed no enhanced inhibitory activity versus an aliphatic, ether, or aromatic linker, indicating that the azo group is not important for binding. An 8-hydroxy substituent also enhanced binding which correlates to the increased potency of xanthurenate over kynurenate. The QDC's exhibited competitive inhibition with the most potent analogue exhibiting a Ki of 37 muM. Molecular modeling and SAR studies were used to elucidate a pharmacophore model. These two key structural groups provide avenues for developing future analogues containing both a regiopositioned lipophilic pocket and a hydrogen-bonding group at the 8-position. Furthermore, these QDC analogues could show possible activity at other biological sites, specifically the NMDA/glycine site.