An analogue of AICAR with dual inhibitory activity against WNV and HCV NTPase/helicase: Synthesis and in vitro screening of 4-carbamoyl-5-(4,6-diamino-2,5-dihydro-1,3,5-triazin-2-yl)imidazole-1-β-d-ribofuranoside

The title compound (4) was synthesized by the reaction of ethyl 1-(2,3,5-tri-O-benzoyl-β-d-ribofuranosyl)-5-formylimidazole-4-carboxylate with excess guanidine in ethanol at reflux. Compound 4 was evaluated in vitro against NTPases/helicases of four different viruses of the Flaviviridae family, including the West Nile virus (WNV), hepatititis C virus (HCV), dengue virus (DENV), and the Japanese encephalitis virus (JEV), employing both an RNA and a DNA substrate. The compound showed activity against NTPase/helicase of WNV and HCV with an IC50 of 23 and 37 μM, respectively, when a DNA substrate was employed, while no activity was observed when an RNA substrate was used. There was no activity against the NTPase/helicase of either DENV or JEV irrespective of whether an RNA or a DNA substrate was employed. Considering that Flaviviridae are RNA viruses, the observed absence of activity against an RNA substrate, but the presence of activity against a DNA substrate is intriguing and somewhat surprising. The preliminary studies show that compound 4 does not form a tight complex with either an RNA or a DNA substrate, suggesting that its mechanism of action may involve direct interaction with the enzyme.

Graphical abstractSynthesis and in vitro screening results of the title compound against Flaviviridae enzymes have been reported. The target compound exhibited anti-helicase activity against WNV and HCV NTPase/helicase with an IC50 of 23 and 37 μM, respectively.Figure optionsDownload full-size imageDownload as PowerPoint slide