Comparison of the antioxidant activity amongst Gingko biloba extract and its main components.

Objective: To compare the antioxidant activity amongst the extract of Ginkgo biloba (EGb) and its main components, flavonoids and terpenoids.
Methods: The induction of EGb, flavonoids and terpenoids on a typical antioxidant enzyme, glutamate cysteine ligase catalytic subunit (GCLC), in cell lines was detected by Western-blot. The effects of EGb, flavonoids and terpenoids on superoxide anion radical (O2*(-)), hydroxyl radical (OH*), rat erythrocyte hemolysis and lipid peroxidation of rat liver homogenate were determined by respective activity methods.
Results: EGb and flavonoids but not terpenoids were demonstrated significantly to induce the antioxidant enzyme (GCLC), directly scavenge O2*(-), OH* and inhibit rat erythrocyte hemolysis and lipid peroxidation of rat liver homogenate. Compared these antioxidant activities between EGb and flavonoids, the activities of flavonoids were weaker than those of EGb, which contains similar dose of flavonoids.
Conclusion: EGb has stronger antioxidant activities than flavonoids, but terpenoids did not show antioxidant activity in this research.