FPPD improved the mitochondrial function in steatosis hepatic cells. (a) Confocal microscopy images of mitochondrial ROS. Scale bars, 50 μm. (b) The levels of mitochondrial ROS detected by microplate reader. (c) The contents of MDA in L02 cells. (d) Confocal microscopy images of JC-1 fluorescence probe. Scale bars, 50 μm. (e) The ratio of JC-1 fluorescence intensity (green/red). (f) The activity of mitochondrial complex I. (g) The contents of NAD+&NADH, NAD+ and NADH. (h) TEM images of L02 cells. Scale bars, 2 μm (top) and 1 μm (bottom). ∗∗, p < 0.01; ∗∗∗, p < 0.001; ∗∗∗∗, p < 0.0001.