Antiviral activity of silymarin in comparison with baicalein against EV-A71

Figures

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  Fig. 1. Cytotoxic effects of (a) silymarin, (b) baicalein (c) baicalin and (d) DMSO in RD cells. Flavonoids were diluted serially in DMEM containing 2% FBS and Rhabdomyosarcoma (RD) cells were treated with the diluted flavonoids under investigation for 24 h. Cytotoxicity was determined by the MTS assay using microplate reader to measure absorbance at 490 nm. Data are presented as mean ± S.E.M. Error bars indicate the range of values obtained from three independent experiments *p < 0.05, **p < 0.01, ***p < 0.001 indicates a significant difference compared to the negative control analysed by t-test

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  Fig. 2. Silymarin and baicalein exhibited extracellular virucidal effects against EV-A71 in a dose-dependent manner. Inhibition of viral infectivity by silymarin determined by 2(a) plaque assays and 2(b) quantification of RNA copy number. Inhibition of viral infectivity by baicalein determined by 2(c) plaque assays and 2(d) quantification of RNA copy number. Data presented as mean ± S.E.M. Error bars indicate the range of values obtained from three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001 indicates a significant difference compared to the negative control analyzed by t-test

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  Fig. 3. Extracellular virucidal activities of silymarin and baicalein against EV-A71 at different co-incubation times determined by plaque assays. a Silymarin (100 μg/mL) or baicalein (54 μg/mL) was co-incubated with EV-A71 for 15, 30, 45 and 60 min at 37 °C. The mixtures from each time point were subsequently inoculated into RD cells. b Silymarin (100 μg/mL) was co-incubated with EV-A71 for 1, 5, 10, 15, 20, 30, 40, 50 and 60 min at 37 °C. The mixtures from each time point were subsequently inoculated into RD cells. Data presented as mean ± S.E.M. Error bars indicate the range of values obtained from three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001 indicates a significant difference compared to the negative control (0 μg/mL) analysed by t-test

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  Fig. 4. Effects of silymarin on cell protection against EV-A71 determined by plaque assays. a Inhibition of viral infectivity by silymarin 4 (b) Inhibition of viral infectivity by baicalein. Data presented as mean ± S.E.M. Error bars indicate the range of values obtained from three independent experiments

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  Fig. 5. Silymarin and baicalein exhibited antiviral activities against EV-A71 in combined virucidal and cell protection assays in a dose-dependent manner. Inhibition of viral infectivity by silymarin determined by 5(a) plaque assays and 5(b) quantification of RNA copy number. Inhibition of viral infectivity by baicalein determined by 5(c) plaque assays and 5(d) quantification of RNA copy. Data presented as mean ± S.E.M. Error bars indicate the range of values obtained from three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001 indicates a significant difference compared to the negative control (0 μg/mL) analysed by t-test

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  Fig. 6. Effects of 100 μg/mL silymarin on the attachment and entry of EV-A71 to Vero cells. a The viral attachment inhibition was calculated as the number of plaques formed by the silymarin-treated virus over the number of plaques formed by the untreated virus. b Viral entry inhibition was calculated as the number of plaques formed by the virus treated with silymarin after attachment to the cells over the number of plaques formed by the untreated virus. Data presented as mean ± S.E.M. Error bars indicate the range of values obtained from three independent experiments. *** p < 0.001 indicates a significant difference in between groups compared by t-test