Fig. 1

PBT434 enhances the release of iron and prevents the generation of hydrogen peroxide. Cultured M17 neuroblastoma cells were loaded with the iron isotope ⁵⁹Fe. The cells were washed and then exposed to a chelator to assess if iron could be removed from the cell. Cells loaded with the iron isotope ⁵⁹Fe were exposed to a PBT434 and the amount of radioactive ⁵⁹Fe released into the media was measured (CPM = counts per minute) or b deferiprone at 0, 1, 10 or 20 μM for 3 h. Deferiprone showed a dose related increase in the levels of ⁵⁹Fe secreted into growth medium. With PBT434 the effect was observed only at the highest dose of 20 μM (*P < 0.05, ** P < 0.01, *** P < 0.0001, One-way ANOVA, Tukey Post Hoc). At the highest concentration, the effect of deferiprone was 5-fold greater than for PBT434. The dashed line represents equivalent values on the two graphs. c PBT434 causes an inhibition of metal mediated redox activity. Fe-citrate (0.4 μM) in the presence of dopamine (DA, 50 mM) generate hydrogen peroxide (H₂O₂) assessed using a cell-free fluorescence-based assay. PBT434 at 10 μM but not PBT434-met significantly reduced H₂O₂ generated by Fe/DA (PBT434-met = analog of PBT434 in which the metal binding site is blocked; One-way ANOVA, Tukey Post Hoc). Dopamine without Fe-Citrate did not produce H₂O₂