A series of erythro-l-(2-hydroxy-3-nonyl) imidazole derivatives have been synthesized and evaluated for adenosine deaminase (ADA) inhibitory activity, in order to introduce simplifications in the ADA inhibitors erythro-942-hydroxy-3-nony1) adenine (EHNA, la) and 3- deaza-EHNA (IC). Opening the pyrimidine or pyridine ring of EHNA or 3-deaza-EHNA respectively led to compounds which are still ADA inhibitors. The most potent compound ...