Development of an (S)-1-{2-[tris(4-methoxyphenyl)methoxy]ethyl}piperidine-3-carboxylic acid [(S)-SNAP-5114] carba analogue inhibitor for murine γ-aminobutyric acid transporter type 4.

A series of GABA uptake inhibitors related to (S)-1-{2-[tris(4-methoxyphenyl)methoxy]ethyl}piperidine-3-carboxylic acid [(S)-SNAP-5114], the most potent mGAT4 inhibitor known so far, were synthesized and biologically evaluated for their inhibitory potency at the four GABA uptake transporters mGAT1-4 stably expressed in HEK-293 cell lines. New analogues were developed with potencies that are similar to or slightly higher than those of current mGAT4 inhibitors, but with distinctly improved chemical stability. (S)-Nipecotic acid derivatives possessing a 2-[1-(4-methoxy-2-methylphenyl)-1,1-bis(4-methoxyphenyl)methoxy]ethyl (DDPM-859) or a 4,4,4-tris(4-methoxyphenyl)but-2-en-1-yl moiety (DDPM-1457) were found to exhibit pIC(50) values of 5.78 and 5.87, respectively. Thus, as mGAT4 inhibitors, these compounds compare well with (S)-SNAP-5114 (pIC(50) =5.71), but are far more stable than the latter. Moreover, DDPM-859 displays a more favorable subtype selectivity for mGAT4 versus mGAT3 than does (S)-SNAP-5114.

Development of imidazole alkanoic acids as mGAT3 selective GABA uptake inhibitors.

A new series of potential GABA uptake inhibitors starting from of 1H-imidazol-4-ylacetic acid with the carboxylic acid side chain originating from different positions and varying in length have been synthesized and tested for the inhibitory potency at the four GABA uptake transporters mGAT1-4 stably expressed in HEK cells. Further two bicyclic compounds with a rigidified carboxylic acid side chain were included in this study. The results of the biological tests indicated that most ω-imidazole alkanoic and alkenoic acid derivatives exhibit the highest potencies as GABA uptake inhibitors at mGAT3.