Prevention of neuronal cell damage induced by oxidative stress in-vitro: effect of different Ginkgo biloba extracts

The effect of two different Ginkgo biloba extracts (GB1 and GB4) was studie d in-vitro on cultured neurons exposed to oxidative stress caused by H2O2(5 0 mu mol L-1) and FeSO4(100 mu mol L-1). Only about 50% of the neurons were still viable at the end of the experiment (8 h) in control conditions, whi le the two extracts dose dependently increased the number of viable cells, in the concentration range 10-200 mug mL(-1). The two Ginkgo biloba extract s differed in their effect on hydroxyl-radical-scavenging capacity: GB1 and GB4 had an IC50 (50 % inhibiting concentration) value of 78 mug mL(-1) and 186 mug mL(-1), respectively. However, both extracts inhibited apoptosis i n cortical neurons after oxidative stress in-vitro. These observations make one suppose that different preparations of Ginkgo biloba have quantitative ly different actions and outline the importance of the contribution of apop tosis prevention toward their neuroprotective action.