Fig. 3: Potential of C-Mn₃O₄ NPs in the regulation of cellular redox condition and protection of mitochondria from oxidative damage.

a Confocal fluorescence micrographs of HEK 293 cells stained with rhodamine 123, Mitosox^TM red, and counterstained with DAPI. Cells were either left untreated or pretreated with C-Mn₃O₄ NPs (30 μg mL⁻¹) prior exposure to H₂O₂ (100 µM). Scale bar: 10 µm. b Intensity of rhodamine 123 as a marker of mitochondrial membrane potential (Δψ_m). An increase in intensity indicates membrane depolarization. c Mitochondrial ROS level as quantified from Mitosox^TM red fluorescence. d Change in Ca²⁺-induced mPTP opening. e ATP content. f Cytochrome c oxidase activity. g Superoxide dismutase (SOD) activity. h Catalase activity. i Glutathione peroxidase (GPx) activity. j Reduced glutathione (GSH) content. k Schematic representation of the redox homeostasis mechanism by C-Mn₃O₄ NPs against H₂O₂ distress through mitochondrial protection. In bar plots data were expressed as Mean ± SD. Violins depict kernel density estimation of the underlying data distribution with the width of each violin scaled by the number of observations at that Y-value. Three lines (from the bottom to the top) in each violin plot show the location of the lower quartile (25th), the median, and the upper quartile (75th), respectively. The shaded area indicates the probability distribution of the variable. Individual data points are represented as colored circles (N = 5). One-way analysis of variance (ANOVA) followed by Tukey’s post hoc multiple comparison test was performed for comparison among the groups. The numbers inside the plots indicate numerical p values. p < 0.05 is considered significant.