Fig. 1

Cytotoxicity of arctiin on A549 cells. A Structure of arctiin. B Arctiin inhibited H9N2 virus-induced plaque formation in MDCK cells. C The number of plaques in (B) were showed. D Arctiin inhibited yield of H9N2 progeny viruses. A549 cells infected with H9N2 viruses (MOI = 0.1) were treated with or without arctiin (100–300 μg/mL). After 24 h, the culture supernatants were collected for progeny virus reduction assay. E Cytotoxicity of arctiin in A549 cells. A549 cells (5 × 10⁴ cells/mL) were treated with arctiin at various concentrations (0 to 800 μg/mL) for 24, 48 and 72 h. Then, MTT assay was carried out to investigate the cytotoxicity of arctiin. The results are expressed as means ± SD. ^*p < 0.05; ^**p < 0.01; ^***p < 0.001 compared with H9N2 virus-infected alone