Figure 3
Dose-dependence of neuroprotective effects of selected herbal extracts and purified compounds. The herbal extracts, Glycyrrhiza glabra (A, left panel), Schizandra chinensis is (B, left panel) and Polygonum cuspidatum (C, left panel), were used in the concentration range of 3 – 100 μg/ml. The pure compounds, glabridin (A, right panel), schisandrin (B, right panel) and resveratrol (C, right panel) were used in the range of 1 – 65 μg/ml. * p value < 0.05; ** p value < 0.01, and *** p value < 0.001 compared with the positive control.