Figure 4.

Novel amino endoperoxide compounds regulate ROS levels in cancer cells. (a) General ROS levels (expressed as fold change) in MCF-10A and MDA-MB-231 cells suspended in the presence of the four amino endoperoxide compounds at indicated concentrations for 0.5 h as measured by CM-H2DCFDA. (b, c) H₂O₂ (b) and O₂⁻ (c) levels in MDA-MB-231 cells treated like in (a) as determined by Amplex Red and 2-methyl-6-(4-methoxyphenyl)-3, 7-dihydroimidazo[1, 2-a] pyrazin-3-one hydrochloride (MCLA) assays, respectively. (d) Representative EPR spectra of DEPMPO-superoxide spin adduct from MDA-MB-231 cells suspended in the presence of the 4-Me. The superoxide adduct of DEPMPO has hyper fine splitting constants of a_N=13.13 G; a_P=55.61 G; a^β_H=13.11 G; a^γ_H=0.71, 0.42, 0.7, 0.25, and 0.6 G. The EPR spectra represent the averaged signals of 10 scans. (e) EPR signal intensity (expressed as percentage of control) at 3480 G from MDA-MB-231 cells in (d). Tiron-treated measurements serve as negative signal controls. (f) Arbitrary relative O₂⁻:H₂O₂ ratios calculated based on H₂O₂ (b) and O₂⁻ (c) values are shown in boxes. Each experiment was independently performed three times with triplicates. The concentration 0 indicates vehicle control and its ROS value was set as 1. Error bars: S.E.M. Comparison was performed against cognate vehicle controls. n.s. represents not significant, * P<0.05, **P<0.01