Intracellular ROS levels. ROS levels after pretreatment with various concentrations of SFE for 2 h followed by treatment with t-BHP (50 μM) for 2h. Treatment with 50 μM t-BHP significantly increased the ROS levels. Pretreatment with SFE decreased the ROS levels in a dose-dependent manner. Values represent mean ± SD (n=5).