Abstract
The 5′-triphosphates of 2′-5′ linked oligoadenylic acids are formed in cells which have been exposed to interferon and may be involved in the antiviral activity of the latter. The lead(II) ion-catalysed oligomerisation of adenosine 5′-phosphorimidazolidate is a convenient route for the preparation of the 5′-phosphates of 2′-5′ linked oligoadenylic acids. The latter can readily be converted to the triphosphates or coupled to the 5′-phosphate of nicotinamide nucleoside to give naturally occurring pyrophosphates which may act as reservoirs for the oligoadenylic acids in cells.
Pyrophosphate analogues, eg, phosphonoacetic and phosphonoformic acids or carbon-substituted methylenebisphosphonic acids are antiviral agents of potential commercial interest as they inhibit the replication of a number of viruses including herpes and influenza. These pyrophosphate analogues do not appear to inhibit virus replication by being incorporated into nucleoside triphosphates which block nucleic acid synthesis. Rather the analogues appear to act by forming stable complexes with an essential metal ion (probably zinc) at the active sites of nucleic acid polymerases of viruses.