Figure 8.

Inhibitory effect of eupafolin, EA, and BuOH fractions on viral 2A protease activity in cell-based FRET assay. HeLa-G2AwtR cells expressed 2A-cleavage motif in FRET probes were infected with EV71 or CVA16 at a MOI of 1, coexistent with treatment of eupafolin, EA, and BuOH fractions. Cells harvested 48 postinfection were subjected to measurement by a fluorescent-plate reader with excitation wavelength at 390/20 nm and emission wavelength at 510/10 nm (for GFP²) or 590/14 nm (for DsRed2). Inhibitory activity was calculated as FRET ratio, that is, intensity of emission at 590/14 nm divided by that at 510/10 nm. *P value < 0.05; **P value < 0.01; ***P value < 0.001 by Scheffe's test.