Luteolin extracted from Platycodon grandiflorum protects retinal pigment epithelial cells from oxidative stress-induced caspase-3 dependent apoptosis

Luteolin, a flavonoid isolated from the flowers of Platycodon grandiflorum (balloon flower, Campanulaceae), has been examined with regard to the inhibition of apoptosis in human retinal pigment epithelium (RPE) cells under oxidative stress. Luteolin from P. grandiflorum protected human RPE cells from oxidative stress-induced cell death. The toxicity of the effective luteolin (1 μM) was very low. Luteolin significantly inhibits reactive oxygen species (ROS) generation in human RPE cells under t-BOOH induced oxidative stress. T-BOOH induced activation of caspase-3 was reduced by 1 μM luteolin, from 1.7 fold to 1.1 fold, compared with untreated control (P < 0.05). These results suggest that luteolin from P. grandiflorum may be used as a potential cytoprotective agent for oxidative stress-induced apoptosis in RPE cells.