(A) Protective effects of caffeic acid isolated from E. annuus leaf on hydrogen peroxide-induced neurotoxicity and (B) membrane damage in PC12 cell system. PC12 cells were pretreated for 48 hours with various concentrations. After 48 hours, cells were treated with 200 μM H2O2 for two hours. Results are presented as mean ± SD of three independent experiments. (A) *P = 0.037, **P = 0.046, vs. positive control.