Figure 7. Evaluation of redox-active drugs in an E. coli model of H₂O₂-induced damage - drugs were added to E coli–containing medium in parallel with H₂O₂.

20 µM compounds were exposed to H₂O₂ for 15 min. The parental (MG1655) strain (A) and catalase/peroxidase-deficient mutant (LC106) (B) were studied; with parental MG1655 5 mM H₂O₂, and with catalase/peroxidase LC106 0.5 mM H₂O₂ was used. The viability was measured via MTT test and expressed as a percentage of the MTT reduction by non-treated cells. At 5 mM H₂O₂, no compound was efficacious in protecting parental strain. At 0.5 mM H₂O₂, the Mn complexes that are relatively stable, or have modest k_cat(H₂O₂), that results in relatively high O₂ production yield, were able to dismute and remove H₂O₂, protecting cell against it. Such interaction, in the case of Fe porphyrin, eliminated both the toxicity of FeP and H₂O₂. Student t-test was used to determine the statistical significance. Mean ± S.E is presented. ^# statistical significance (p<0.05) compared to untreated cells; ^$ statistical significance (p<0.05) compared to cells treated with H₂O₂ only.