N-phenethylphenazine-1-carboxamide, a novel antiviral compound against infectious bronchitis virus.

Avian infectious bronchitis virus (IBV) is a globally prevalent and highly contagious avian pathogen that imposes significant disease burden and economic losses on the poultry industry. Given the challenges associated with current vaccine-based immunization strategies, there is an urgent need to develop novel therapeutic approaches for the prevention and treatment of IBV infection. In this study, a newly synthesized compound, N-phenethylphenazine-1-carboxamide (SQXA-12), was evaluated for its potent inhibitory effects on IBV replication. The cytotoxicity assay revealed CC50 values of 151.2 µM in H1299 cells, 147.0 µM in Vero cells, 96.83 µM in DF-1 cells, 166.6 µM in HeLa cells, and 136.7 µM in Mac-145 cells, while the EC50 value of SQXA-12 was determined to be 12.25 µM. Sensitivity tests against a panel of viruses, including vesicular stomatitis virus (VSV), human coronavirus OC43 (HCoV-OC43), porcine epidemic diarrhea virus (PEDV), Newcastle disease virus (NDV), porcine reproductive and respiratory syndrome virus (PRRSV), and avian influenza virus H9N2 (AIV-H9N2), demonstrated that SQXA-12 exhibits potential broad-spectrum antiviral activity against both positive- and negative-sense RNA viruses. Collectively, these findings underscore the promising therapeutic potential of SQXA-12 for the treatment of IBV infection.