Measurement of intracellular ROS levels
The ROS levels were quantified in accordance with the protocol of the Reactive Oxygen Species Assay Kit (Beyotime Biotechnology, China). Cells were cultured in 6-well plates (3x105 per well) treated with indicated concentrations of Ziyu II for 24 h and stain with Museā„¢ Oxidative Stress reagent at 37oC for 30 min. Cells were then collected for ROS analysis using FACSCalibur flow cytometer (BD Biosciences, San Jose, CA, USA).