Paeonolum reduced MPP+-induced intracellular ROS production in PC12 cells. Cells were preincubated with paeonolum for 30 min and then exposed to 250 μM MPP+ for a further 24 h. Pretreatment with different concentrations of paeonolum significantly attenuated MPP+-induced intracellular ROS at 24 h following MPP+. Intracellular ROS is indicated by the DCF-DA values of each experimental group and are expressed as percentage of the control group. ROS was detected using DCF-DA. Representative images were selected from three independent experiments. Quantitative data are presented in the bar graph. Values are means ± SEM. *P < 0.01 compared with vehicle control. The results were obtained from three independent experiments performed in triplicate.