Discovery and mechanistic insights of dibenzoylmethane as a broad spectrum inhibitor of coronavirus.

Coronavirus, a large family of positive-sense RNA viruses, are responsible for both mild and severe respiratory illnesses, ranging from the common cold to life-threatening conditions. Despite significant advances in vaccine and antiviral development, the high mutability of human coronaviruses (HCoVs), such as SARS-CoV-2, presents a major challenge in treating these infections. Effective, broad-spectrum antiviral drugs are urgently needed to address both current and future HCoV outbreaks. Here, we conducted high-throughput screening of a natural product library containing 3407 compounds to identify potential antiviral agents against HCoV-OC43 and HCoV-229E. We identified several natural products with inhibitory effects on HCoV-229E, HCoV-OC43, and the SARS-CoV-2 variants Delta (B.1.617.2) and Omicron (BA.5) in vitro without evident cytotoxicity. Among these, dibenzoylmethane (DBM) not only demonstrated broad-spectrum anticoronavirus activity in vitro but also effectively inhibited HCoV-OC43 replication in a BALB/c mouse model. Pharmacokinetic analysis revealed that DBM, when administered orally, maintained effective concentrations in the blood over an extended period, suggesting its suitability for oral administration. Mechanistically, DBM was found to regulate caspase-6, a host factor that suppresses interferon signalling and promotes HCoV replication. These findings highlight DBM as a promising candidate for the development of therapeutics targeting HCoVs, offering potential for treating infections by both established and emerging HCoVs.