Monocyclic l-Nucleosides with Type 1 Cytokine-Inducing Activity

A series of 1,2,4-triazole l-nucleosides were synthesized and evaluated for their ability to stimulate type 1 cytokine production by activated human T cells in direct comparison to the known active agent ribavirin. Among the compounds prepared, 1-β-l-ribofuranosyl-1,2,4-triazole-3-carboxamide (5, ICN 17261) was found to be the most uniformly potent compound. Conversion of the 3-carboxamide group of 5 to a carboxamidine functionality resulted in 1-β-l-ribofuranosyl-1,2,4-triazole-3-carboxamidine hydrochloride (10), which induced cytokine levels comparable to 5 for two of the three type 1 cytokines examined. Modification of the carbohydrate moiety of 5 provided compounds of reduced activity. Significantly, ICN 17261 offers interesting immunomodulatory potential for the treatment of diseases where type 1 cytokines play an important role.