Respiration, citrate synthase activity, and ATP level of SH-SY5Y cells after incubation with hesperitin nanocrystals (HstN). Cells were incubated for 24 h with 10 µM HstN or PlantaCare as control, N = 12. Respective mean values ± SD are shown. * p < 0.05, ** p < 0.01, *** p < 0.001 and **** p < 0.0001. Significance was determined by Student’s unpaired t-test. Respiration of (A) SH-SY5Y-MOCK and (B) SH-SY5Y-APP695 cells adjusted to international units (IU) of citrate synthase activity. Citrate synthase activity of (C) SH-SY5Y-MOCK cells and (D) SH-SY5Y-APP695 cells. Values are given as IU of citrate synthase activity. ATP level of (E) SH-SY5Y-MOCK cells and (F) SH-SY5Y-APP695 cells after 24 h incubation with 0.01–10 µM HstN. Cells treated with cell culture medium served as control (100%).