ABSTRACT
Modification of the heterocyclic base moiety of nucleosides has been less extensively studied than sugar modifications, however research in this area has led to many compounds with potent activity. 5-Ring heterocyclic nucleosides structurally derived from 5-amino-l-p-D-ribofuranosylimidazole-4-carboxamide (AICAR, 1.29) by modification at the 5-position, such as Bredinin (4.1) and EICAR (1.55), or by modification of the ring skeleton, such as Ribavirin (1.8) and TCNR (4.2), are known to exhibit a broad spectrum of activity against a range of viruses including hepatitis C, influenza and respiratory syncytial virus,1 in addition to a variety of other chemotherapeutic applications.
