Synthesis of a Novel Class of 1,3-oxathiolane Nucleoside Derivatives of T-705 and Evaluation of Their Anti-influenza A Virus and Anti-HIV Activity

Background: T-705 (Favipiravir) is a broad spectrum antiviral agent approved for stockpiling in Japan and currently in Phase 3 testing in the United States. Against influenza, it acts as a prodrug, converted intracellularly to selectively inhibit viral RNA-dependent RNA polymerase or similar enzymes. This is regarded as a novel antiviral mechanism of action, reducing crossresistance to other existing anti-influenza drugs. Objective: To develop new analogs, a class of 1,3-oxathiolane nucleoside derivatives of T-705 was designed and synthesized in this work. Results: Anti-influenza activity and Anti-HIV activity of these compounds were evaluated. Compound 1a displayed activity against A H1N1 with an IC50 of 40.4 μmol/L. Compound 1b showed weak activity against HIV with a viral suppression rate of 70-80% at 30 μmol/L. Conclusion: A class of 1,3-oxathiolane nucleoside derivatives of T-705 was designed and synthesized, and one of them was identified as a novel scaffold against viral infection.