Figure 3. The protecting effect of GSPE was inverse ratio to H₂O₂ concentration. The cells were pretreated with 20.0 mg/l GSPE for 12 h, then exposed to different concentration of H₂O₂ (50, 100, and 200 μmol/l) for 24 h. The cell viability was measured by MTT assay. The results showed the protecting effect of GSPE was inverse ratio to H₂O₂ concentration.