Fig. 7

Oxidative stress and ROS induction in cells after treatment with FAC, Venofer or IONPs. A and B ROS generation observed by DHR fluorescence and quantitative image analysis of DHR fluorescence intensity using Image J software: Control (−), untreated Vero E6 cells; and control (+), Vero E6 cells incubated with 1 mM H₂O₂. Images were taken with a 63X oil objective under a 3X zoom. C Quantification of oxidative stress gene expression by qRT-PCR (mRNA levels) in Vero E6 cells after treatment with FAC, Venofer or the different IONPs (Venofer, FeraSpin R, APS-IONP-10, DMSA-IONP-10 or DMSA-IONP-16). The expression was compared to that in untreated cells and the data were normalized to the expression of GAPDH. D Glutathione content in untreated [Control (−)] Vero E6 cells, and in Vero E6 cells incubated for 24 h with FAC, Venofer or IONPs, or with 1 mM H₂O₂ [Control (+)]. E Effect of ROS on the antiviral activity of FAC, Venofer or the IONPs. Confluent monolayers of Vero E6 cells were treated for 24 h with N-acetylcysteine (NAC) or left untreated as a control. The cells were then infected with SARS-CoV-2 (MOI, 0.001) and 1 hpi, the extracellular medium containing the virus was replaced with a suspension of FAC, Venofer and IONPs, together with NAC (200 µM), or with a suspension of the FAC, Venofer or IONPs without NAC as a control. The medium was collected from the cells and titrated at 48 hpi. The data are shown as mean ± SD (n = 3) and analyzed with a two-way analysis of variance (ANOVA) and Tukey’s multiple comparisons test: *p < 0.05, **p < 0.01, ***p < 0.001