Nobiletin protects human retinal pigment epithelial cells from hydrogen peroxide-induced oxidative damage

Nobiletin (3',4',5,6,7,8-hexamethoxyflavone), a dietary polymethoxylated flavonoid found in Citrus fruits, has been reported to have antioxidant effect. However, the effect of nobiletin on human retinal pigment epithelium (RPE) cells induced by hydrogen peroxide (H₂ O₂ ) is still unclear. Therefore, we investigated the protective effect of nobiletin against H₂ O₂ -induced cell death in RPE cells. Our results demonstrated that nobiletin significantly increased cell viability from oxidative stress. Nobiletin inhibited H₂ O₂ -induced ROS production and caspase-3/7 activity in ARPE-19 cells. Furthermore, nobiletin significantly increased Akt phosphorylation in ARPE-19 cells exposed to H₂ O₂ . Meanwhile, LY294002, an inhibitor of PI3K/Akt, abolished the protective effect of nobiletin against H₂ O₂ -induced decreased cell viability and increased caspase-3/7 activity in ARPE-19 cells. In summary, these data show that nobiletin protects RPE cells against oxidative stress through activation of the Akt-signaling pathway. Thus, nobiletin should be an oxidant that attenuates the development of age-related macular degeneration.