Virucidal activity and differential antiviral efficacy of curcuminoid preparations against porcine epidemic diarrhea virus and feline infectious peritonitis virus.

Curcuminoids from Curcuma longa L. have exhibited antiviral activity against several human viruses; however, their comparative efficacy against animal coronaviruses remains unclear. This study evaluated the antiviral and virucidal effects of curcumin (CUR), demethoxycurcumin (DMC), bisdemethoxycurcumin (BDMC), a curcuminoid-rich extract (CRE), and its solid dispersion (CRE-SD) against porcine epidemic diarrhoea virus (PEDV) and feline infectious peritonitis virus (FIPV). Against PEDV, all compounds exhibited multi-stage antiviral activity, confirmed by cytopathic effect reduction, IPMA, and RT-qPCR. DMC was the most consistently potent (EC50 = 0.48-0.98 µg/mL), followed by BDMC and CUR (0.37-4.47, and 1.50-1.99 µg/mL, respectively), while only BDMC lacked prophylactic activity. Purified curcuminoids showed limited activity against FIPV, though this virus remained susceptible to the extract formulations. Molecular docking supported the experimental findings. Notably, CRE and CRE-SD exerted strong virucidal activity against both viruses, suggesting synergistic effects of multiple constituents. These findings highlight curcuminoid formulations as promising veterinary antivirals and disinfectants.