The Anthocyanins, Oenin and Callistephin, Protect RPE Cells Against Oxidative Stress

The retinal pigment epithelium (RPE) is a highly metabolic layer of postmitotic cells lining Bruch's membrane in the retina. While these cells contain endogenous photosensitizers that mediate blue light-induced damage, it has also been shown that blue light exposure damages mitochondrial DNA in RPE cells resulting in mitochondrial dysfunction and unregulated generation of reactive oxygen species (ROS). As RPE cells are postmitotic, it is imperative to decrease oxidative stress to these cells and preserve function. Dietary plant-derived antioxidants such as anthocyanins offer a simple and accessible solution for decreasing oxidative stress. The anthocyanins malvidin-3-O-glucoside (oenin) and pelargonidin-3-O-glucoside (callistephin) were tested for their ability and efficacy in decreasing ROS generation and preserving mitochondrial redox activity in blue light-irradiated ARPE-19 cells. A significant decrease in intracellular ROS with concurrent increase in mitochondrial redox activity was observed for tested concentrations of oenin, while callistephin was beneficial to stressed cells at higher concentrations. These findings suggest anthocyanins are effective antioxidants in blue light-stressed RPE cells in vitro. Additionally, oxidation products of these anthocyanins were examined using LC/MS and findings suggest the possibility of multiple oxidation sites for these compounds.