Figure 6. Oxidative stress evaluation/superoxide anion production (hydroethidine assay) at 24 h (gray bars) and 48 h (black bars). The results expressed as percentages (means±SD) of the 100% of control DMEM and signals emitted by cell population are reported over the neutral red test as an indication of viable cells. Compared to control, a significant (p<0.001) increase of fluorescence values at 24 h and 48 h was observed in HO and BAK conditions alone (except for HO50 mM and BAK3.10−4% at 24 h, and BAK10−4% at 24h and 48h). The combination of any HO with BAK3.10−4% or BAK5.10−4% induced a superoxide anion increase (p<0.001). The following letter codes were used for statistical comparisons with (b) all BAK concentrations, (b1) BAK10−4%, (b3) BAK5.10−4%, (b5) BAK3.10−4%, (h) all HO solutions, (h50) HO50 mM, (h60) HO60 mM, (h90) HO90 mM, corresponding to a statistically significant difference at p<0.001.