Figure 3.

Apigenin has an intracellular antiviral activity. (A) Direct virucidal activity of apigenin against FMDV. Moreover, 10⁵ PFU FMDV particles were incubated with apigenin at specific concentrations for 2 h at 37 °C. BHK-21 cells were infected with the viral suspension that was diluted 1000-fold in triplicate to determine the direct virucidal activities of apigenin against extracellular FMDV; (B,C) Therapeutic effect of apigenin against FMDV infection. BHK-21 cells were infected with FMDV at an MOI of 0.2. Apigenin was added at specific concentrations at 12 hpi, and cells and cultural supernatants were harvested at another 12 hpi. (B) CPE images were obtained at 24 hpi; (C) Viral titers; (D,E) Apigenin inhibited FMDV intracellular replication. BHK-21 cells were infected with FMDV at an MOI of 0.1, and were cultured in the presence or absence of apigenin (20 µg/mL). Cells and cultural supernatants were harvested at specific time; (D) The progeny virus titers in the supernatants were determined via PFU assay; (E) The RNA level of the FMDV 3D gene was analyzed via qRT-PCR. GAPDH served as the normalizer. The experiment was performed three times independently.