A Study on Gamma-Aminobutyric Acid (GABA) and Its Analogues by Using Molecular Orbital Methods: On Epileptogenicity of New Quinolones

Abstract: Using the molecular orbital methods, we examined molecular structure, electron density distribution, electrostatic potential field and receptor structure of gamma-aminobutyric acid (GABA), and its analogues. The following findings were obtained: a comparison of the biological activity and the morphology electrostatic potentials of GABA analogues disclosed that the active site is the amino group, and the biological activity correlates closely with the electrostatic potential structure around the amino group. The active sites were compared between the receptor-binding molecules and the GABA uptake inhibitory molecules, and the results suggested that the receptor structure differed between the two groups of molecules and that the GABA A receptors had two subtypes. On these results, the epileptogenicity of new quinolones was studied using this method. These results suggested that the new quinolones blockaded the GABA receptor-binding system and that the important active site of the new quinolones for GABA receptor-binding was the the piperazyl amino group. These results suggested that the concentration of zwitterion type of the new quinolones was very important clinically.