Guanidino acids act as rho1 GABA(C) receptor antagonists.

Mary Chebib, Navnath Gavande, Kit Yee Wong, Anna Park, Isabella Premoli, Kenneth N Mewett, Robin D Allan, Rujee K Duke, Graham A R Johnston, Jane R Hanrahan

Neurochemical research 2009 Oct

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GABA(C) receptors play a role in myopia, memory-related disorders and circadian rhythms signifying a need to develop potent and selective agents for this class of receptors. Guanidino analogs related to glycine, beta-alanine and taurine were evaluated at human rho(1)GABA(C) receptors expressed in Xenopus oocytes using 2-electrode voltage clamp methods. Of the 12 analogs tested, 8 analogs were active as antagonists and the remaining were inactive. (S)-2-guanidinopropionic acid (IC(50) = 2.2 microM) and guanidinoacetic acid (IC(50) = 5.4 microM; K (B) = 7.75 microM [pK (B) = 5.11 +/- 0.06]) were the most potent being competitive antagonists at this receptor. In contrast, the beta-alanine and GABA guanidino analogs showed reduced activity, indicating the distance between the carboxyl carbon and terminal nitrogen of the guanidino group is critical for activity. Substituting the C2-position of guanidinoacetic acid with various alkyl groups reduced activity indicating that steric effects may impact on activity. The results of this study contribute to the structure-activity-relationship profile required in developing novel therapeutic agents.

Citation

Mary Chebib, Navnath Gavande, Kit Yee Wong, Anna Park, Isabella Premoli, Kenneth N Mewett, Robin D Allan, Rujee K Duke, Graham A R Johnston, Jane R Hanrahan. Guanidino acids act as rho1 GABA(C) receptor antagonists. Neurochemical research. 2009 Oct;34(10):1704-11