Role of phenolic compounds on blue light induced retinal pigment cell damage: an in vitro study

Abstract

Age-related macular degeneration (AMD) is a progressive eye disease that affects the macula, causing blurred central vision making it difficult for diagnosed patients to see fine details and have trouble with everyday tasks. Recent studies have suggested that blue light is able to cause damage to eyes that progresses to AMD. Exposure of blue light to our eyes is a growing concern in our everyday lives due to the prevalence of computers, phones, and tablets. Blue light is responsible for cell damage, cell death, and oxidative stress, all of which can lead to vision loss. Resveratrol and pterostilbene are polyphenols found in the skin of various fruits including grapes and blueberries and have been well studied for their antioxidant properties. The aim of this study was to investigate the biological activity of resveratrol and pterostilbene on cell viability (MTS assay), cell death markers (Caspase-3/7 activity, Caspase-3 protein expression and Propidium Iodide assay), antioxidant potential (catalase and MnSOD), and the levels of oxidative stress (4HNE), in retinal pigment ARPE-19 cells exposed to blue light. ARPE19 cells were incubated with a pre-treatment of 50µM and 100µM of resveratrol or 10µM and 250µM of pterostilbene for 4 hours followed by the exposure of blue light (475nm) for 12 hours. Blue light exposure on ARPE-19 cells resulted in a 56% reduction (p<0.0001) in cell viability along with an increase in caspase 3/7 activation, and a 50% increase (p<0.0001) in cell necrosis. This was accompanied by an increase in protein adduct formation of 4HNE and protein expression of antioxidants such as, catalase, and MnSOD. Resveratrol treatment of 50µM was able to maintain cell viability by 37% (p<0.05), and significantly (p<0.05) reduced the caspase 3/7 fluorescence activity when compared to control cells exposed to blue light. Cellular necrosis was also significantly reduced (p<0.05) by both 50µM and 100µM treatments of resveratrol. In conclusion, the damaging effects of blue light was mitigated by treatments of resveratrol in ARPE-19 cells. Pterostilbene treatments of 10 and 25µM were unable to maintain cellular viability across both MTS assay and caspase 3/7 fluorescence assay. Both concentrations showed opposite results when compared to the 50 and 100µM treatments of resveratrol.