Aminomethyl-1,2,4-benzothiadiazines as potential analogues of gamma-aminobutyric acid. Unexpected discovery of a taurine antagonist.

A series of 6- and 8-(aminomethyl)-4H-1,2,4-benzothiadiazine 1,1-dioxides has been synthesized and tested for interaction with various GABA systems. None of the compounds showed significant GABA-mimetic properties, but unexpectedly, compound 7 [6-(aminomethyl)-3-methyl-4H-1,2,4-benzothiadiazine 1,1-dioxide] possessed the properties of a selective antagonist of taurine, as measured by the antagonism of taurine-induced inhibition of rat cerebellar Purkinje firing.