Fig 3. Effects of AS-IV on influenza virus in A549 cells. (A) A549 cells infected with IAV were treated with 50,75, and 100μM AS-IV, and the infection rate of IAV in A549 cells in each group was observed after 16h, with a scale bar, of 100 μ m. (B, C) Western blot detected NP protein expression in A549 cells treated with AS-IV after influenza virus infection. (D)100μM AS-IV treated A549 cells infected with IAV, and immunofluorescence was performed at different time points (2h, 4h, 6h, 8h, 10h, 12h) to observe the effect of AS-IV on nuclear membrane shuttle transport of IAV NP protein in A549 cells, with scale bar,20 μ m. The values are expressed as the mean ± SD. of three independent experiments. ns, no significant difference. * P < 0.05, ** P < 0.01.
3.2. AS-IV down-regulates ROS induced by influenza virus infection
To detect the antioxidant effects of AS-IV, intracellular TAC, SOD, GPX, CAT, MDA, and ROS levels were measured. We confirmed that the levels of intracellular TAC, SOD, GPX, and CAT were significantly reduced after influenza virus infection, while AS-IV treatment restored the inhibition of TAC, SOD, GPX, and CAT by influenza virus infection (Fig. 4A-D). The results of MDA detection showed that MDA concentration in the IAV group was increased compared with the NC group, while MDA level in AS-IV-treated cells was down-regulated compared with the IAV group (Fig. 4E). As shown in flow cytometry analysis, the ROS levels were dramatically elevated after influenza virus infection, while the levels of ROS for AS-IV groups were rescued after treatment (Fig. 4F).