Anchimerically Activatable Antiviral ProTides

This work describes the synthesis and biological evaluation of an anchimerically activated proTide of 2′-C-β-methylguanosine as an inhibitor of dengue virus 2 (DENV-2). The proTide incorporates a chemically cleavable 2-(methylthio)­ethyl moiety and a HINT1 hydrolyzable tryptamine phosphoramidate. Inhibition of DENV-2 replication by proTide 6 was 5-fold greater than the parent nucleoside while displaying no apparent cytotoxicity. Furthermore, we demonstrate with a HINT1 inhibitor that the anti DENV-2 activity of the proTide correlates with the activity of HINT1. Taken together, these results demonstrate that a phosphoramidate based pronucleotide that undergoes an initial nonenzymatic activation step based on anchimeric assistance followed by P–N bond cleavage by HINT1 can be prepared.