Abstract
Antitumor activity of 8-azaguanine was enhanced by simultaneous administration of 5-amino-4-imidazolecarboxamide (AICA). This effect was suggested to be due to the inhibition of guanine deaminase (3.5.4.3) by AICA. 1-β-D-Ribofuranosyl-and 5-formamide derivatives of AICA were not inhibitory. In continuation of a previous report, inhibitory compounds for guanine deaminase more potent than AICA were searched among derivatives of imidazole. 4-Imidazolecarboxamide was thus found as a potent inhibitor.
