Ginkgo biloba attenuates oxidative stress in macrophages and endothelial cells

The action of Ginkgo biloba extract (GBE) as an antioxidant was studied using various models of oxidative stress in macrophages and vascular endothelial cells. GEE was incubated with murine macrophages (J774) at 37 degrees C and 5% CO2 for 1 h; oxidative burst was triggered by zymosan. The intensity of fluorescence was measured directly in 96-well plates using a computerized microplate fluorometer at 485 nm excitation and 530 nm emission. GEE exhibited both time- and concentration-dependent suppression of oxidative burst. Confluent monolayers of bovine pulmonary artery endothelial cells (PAEC) were preincubated with different concentrations of GEE for 16 h, washed, and then exposed to an organic oxidant tert-butyl hydroperoxide (tBHP) for 2 h. Lipid peroxidation products of PAEC were determined by measuring thiobarbituric acid-reactive substances (TEARS). Cell injury was assessed by measuring the release of intracellular lactate dehydrogenase (LDH), and cell viability was determined by the methylthiazol tetrazolium (MTT) assay. tBHP increased production of TEARS in PAEC. Preincubation with GEE inhibited the increase of TEARS induced by tBHP. GEE protected biomembranes from oxidative injury by decreasing intracellular LDH leakage from PAEC. MTT assay showed that GEE minimized loss of cell viability induced by oxidative injury. The extensive antioxidant effect of GEE may be valuable to the prevention and treatment of various disorders related to free radical-induced pathology.