TCM theory-inspired discovery of DNJ-flavonoid conjugates as broad-spectrum anti-SARS-CoV-2 agents by primarily targeting ER-associated glycoprotein folding process

The global COVID-19 pandemic caused by SARS-CoV-2 has underscored the urgent need for the development of new broad-spectrum antivirals to combat its high mutation rate and the emerging variants. Host ER α-glucosidases I/II are promising host-targeted therapeutic targets for the development of broad-spectrum antivirals against viral strains that depend on ERQC for infectivity. Herein, we designed and synthesized a series of TCM theory-inspired DNJ-flavonoid conjugates as novel α-glucosidase inhibitors, which were screened against their in vitro antiviral activities in non-replicative SARS-CoV-2 pseudovirus (PsV) assay. Remarkably, DNJ-20 not only demonstrated remarkable inhibition activity against α-glucosidase and viral entry process, but also exerted potent and broad-spectrum anti-coronaviral activity against SARS-CoV-2 pseudovirus (PsV), several SARS-CoV-2 variants, as well as HCoV-229E and HCoV-OC43, with EC 50 values up to 1.49 μM, which is more potent than the benchmark α-glucosidase inhibitor UV-4 ( DNJ-3 ). Besides, it had no observable cytotoxicity in HeLa-ACE2, HEK-293T and Beas-2B cells. Therefore, TCM theory-inspired DNJ-flavonoid conjugates can be served as promising drug leads for pan-coronavirus therapeutic development to combat current and future coronavirus pandemics.