A variety of mesoionic xanthines including mesoionic thiazole [3, 2-cu] pyrimidines, benzothiazolopyrimidines, and 1, 3, 4-thiadiazolo [3, 2-a] pyrimidines were antagonists of Al- adenosine receptors (inhibition of binding of [3H]-cyclohexyladenosine) and A2-adenosine receptors (inhibition of 2-chloroadenosine-elicited accumulations of cyclic AMP) in brain tissue. Most of the compounds were less potent than theophylline and none were ...
