Novel AR-12 derivatives, P12-23 and P12-34, inhibit flavivirus replication by blocking host de novo pyrimidine biosynthesis

Abstract

The genus Flavivirus contains many important pathogens, including dengue virus (DENV), Zika virus (ZIKV), and Japanese encephalitis virus (JEV). AR-12 is a celecoxib-derived anticancer agent that possesses antiviral activity against a broad range of viruses. We pharmacologically exploited this unique activity to develop additional antiviral agents, resulting in the production of the AR-12 derivatives P12-23 and P12-34. At nanomolar concentrations, these compounds were effective in suppressing DENV, ZIKV and JEV replication, exhibiting 10-fold improvements in the efficacy and selectivity indices as compared to AR-12. Regarding the mode of antiviral action, P12-23 and P12-34 inhibited viral RNA replication but had no effect on viral binding, entry or translation. Moreover, these AR-12 derivatives co-localized with mitochondrial markers, and their antiviral activity was lost in mitochondria-depleted cells. Interestingly, exogenous uridine or orotate, the latter being a metabolite of the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH), abolished the antiviral activity of AR-12 and its derivatives. As DHODH is a key enzyme in the de novo pyrimidine biosynthesis pathway, these AR-12 derivatives may act by targeting pyrimidine biosynthesis in host cells to inhibit viral replication. Importantly, treatment with P12-34 significantly improved the survival of mice that were subcutaneously challenged with DENV. Thus, P12-34 may warrant further evaluation as a therapeutic to control flaviviral outbreaks.