Identification of adenosine analogues as nsp14 N7‑methyltransferase inhibitors for treating coronaviruses infection

[Display omitted] •Using SAM as a lead, we designed and synthesized 21 nucleoside analogs as nsp14 Mtase inhibitors.•Bioactivity screening identified nucleoside MTI013, with a terminal amide, as strongly anti-coronavirus.•The RdRp and nsp14 Mtase inhibitors exhibit a synergistic anti-coronavirus effect.•MTI013 selectively inhibited nsp14 with little or no activity against other SAM substrate methyltransferases. Coronaviruses are RNA viruses that have coevolved with humans and animals over time, exhibiting high mutation rates and mortality rates upon epidemic outbreaks. The nonstructural protein (nsp14) is crucial for various coronaviruses processes, including genome replication, protein translation, virus particle assembly, and evasion of host immunity via RNA methylation modification. In this study, a series of adenosine analogs were designed, synthesized, and evaluated for their inhibitory activities. Among them, MTI013 exhibited the strongest nsp14 MTase inhibition and antiviral activity, with an IC50 of 10.33 μM in HCoV-229E-infected Huh7 cells, along with low cytotoxicity. When combined with the RdRp inhibitor ATV014, MTI013 showed a synergistic antiviral effect, indicating its potential both as a standalone therapy and in combination treatments. Furthermore, MTI013 displayed high selectivity against the SARS-CoV-2 nsp10-nsp16 complex and five human methyltransferases. These results offer valuable structural insights for future exploration of nsp14 as a drug target for SARS-CoV-2 and other coronaviruses.