Synthesis and in vitro inhibitory activity of N-arylsulfonamide adenosine analogues designed to target SARS-CoV-2 nsp14 N7-methyltransferase

This study presents the design, synthesis, and biological evaluation of novel N -arylsulfonamide nucleosides as inhibitors of the SARS-CoV-2 nsp14 N 7-methyltransferase. Several compounds demonstrate potent nanomolar inhibition in vitro , with structure-activity relationship analysis revealing the importance of aryl substituents on activity and physicochemical properties. Approaches aimed to improve cellular delivery using carbonate and iso butyryl prodrugs show partial conversion to the active form upon incubation in cell extracts, while orthoester prodrugs remain stable and inactive. Additionally, a fluorescent analogue was synthesized to track intracellular uptake and distribution, confirming cytoplasmic localization. These results highlight the N -arylsulfonamide nucleoside scaffold as a promising antiviral chemotype against SARS-CoV-2, and emphasize the critical role of chemical modifications for optimizing biological activity and pharmacokinetic profiles toward effective COVID-19 therapies. • Structural optimization of SARS-CoV-2 nsp14 N 7-methyltransferase inhibitors. • SAR analyses revealed the crucial role of aryl substitutions on the sulfonamide. • Prodrug strategies to improve cellular uptake and metabolic stability. • Intracellular uptake and cytoplasmic accumulation (mitochondria) of dansyl nucleoside. • Moderate antiviral activity in SARS-CoV-2-infected cells.