Fig. 4

Extracts from the stems of J. multifida inhibited influenza A H1N1 viral growth. MDCK cells were infected with A/PR/8/34 (MOI; 0.001) for 1 h, and then the infected cells were washed. H₂O, EtOAc, Hex, or CHCl₃ extracts from the stems of J. multifida (25 μg/mL in 0.5% DMSO) (n = 7 each) (a) were added to the cells in the infection medium supplemented with 3 μg/mL TPCK-treated trypsin. DMSO (0.5%) (n = 7) or ribavirin (50 μM in 0.5% DMSO) (n = 7) were the negative and positive controls, respectively, for the inhibition of influenza A viral growth. In addition, the same experiment was performed with DMSO (0.5%), ribavirin (50 μM in 0.5% DMSO), and 12.5 μg/mL CHCl₃extract from the stems of J. multifida (in 0.5% DMSO) (n = 12 each) (b). The conditioned culture medium was collected at the indicated time points, added to MDCK cells, and the treated cells were immunostained with an antibody to influenza A viral NP. The viral titers (PFU/mL) were calculated from the number of stained cells. The data are the mean ± SEM representative of three independent experiments. *p < 0.05; **p < 0.01; ***p < 0.001 in comparison with DMSO