1,7-Bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one inhibits SARS-CoV-2 by targeting the nucleocapsid protein

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally since 2020. The nucleocapsid (N) protein plays a crucial role in the life cycle of SARS-CoV-2. Here, we established a method to screen inhibitors of N protein by using microscale thermophoresis assays to obtain potential anti-SARS-CoV-2 agents. We identified 1,7-bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one (N-17, a diphenylheptane) as a compound with outstanding inhibitory activity. We further validated the binding of N-17 to the N-terminal domain of N protein (N-NTD) by using drug affinity responsive target stability assays. We evaluated the ability of N-17 to bind N protein and predicted the affinity of N-17 to the N-NTD with molecular docking and molecular dynamics simulation. N-17 exhibited excellent anti-viral activity against HCoV-OC43 and SARS-CoV-2, with EC50 values of 0.16 ± 0.01 μM and 0.17 ± 0.07 μM, respectively. Thus, we discovered a novel SARS-CoV-2 inhibitor targeting the N protein and validated its anti-viral activity in vitro. Our results may contribute to the development of promising therapeutic agents for COVID-19.