Antiviral and Immunomodulatory Effects of α-Mangostin Against Feline Infectious Peritonitis Virus: In Vitro Assay

Feline infectious peritonitis virus (FIPV), caused by a mutated form of feline coronavirus, poses a significant threat to feline health worldwide, with limited therapeutic options available. This study investigated the antiviral potential of α-mangostin (α-MG) and its enriched extracts (AMEs), obtained via microwave-assisted extraction, against FIPV. We evaluated their cytotoxicity, direct virucidal activity, and antiviral activity in CRFK cells. Both α-MG and AMEs demonstrated significant antiviral activity, with EC50 values from 2.71 to 2.88 μg/mL and favorable selectivity indices (3.25–3.66). Notably, AMEs exhibited direct virucidal effects, effectively reducing viral titers. Furthermore, treatment with these compounds significantly reduced inflammatory cytokine expression (IFN-β, TNF-α, and IL-6 mRNA levels) and decreased viral loads in FIPV-infected cells. Drug combination studies using the ZIP model revealed enhanced cooperative effects when AMEs and α-MG were combined with GC-376 or GS-441524, with GC-376 combinations showing particularly strong synergistic potential. These findings suggest that α-MG and AMEs are promising candidates for FIPV treatment, either as monotherapy or in combination therapy. This study provides insights into developing novel therapeutic strategies to combat FIPV infections and offers a foundation for future veterinary antiviral drug development.