Date of Award

Fall 2006

Project Type

Dissertation

Program or Major

Animal and Nutritional Sciences

Degree Name

Doctor of Philosophy

First Advisor

Joanne Curran-Celentano

Abstract

Inflammation and oxidative stress play a significant role in the pathogenesis of age-related macular degeneration (AMD). In AMD, retinal pigment epithelium (RPE) cells are damaged by oxidative stress and die via the process of apoptosis. Anthocyanins from fruits and berries, such as bilberry (Vaccinium myrtillus), possess significant antioxidant activity in vitro and have been used in "traditional medicine" to treat AMD. It is not clear whether intracellular concentrations of anthocyanins are sufficient to quench radical species and mitigate oxidative stress in vivo. In this research project, human RPE cells in vitro were used to establish an oxidative stress model in which the effects of anthocyanin and phenolics from a bilberry extract could be tested for their antioxidant potential and ability to inhibit hydrogen peroxide-induced apoptosis. High-pressure liquid chromatography with ultraviolet, electrochemical, and mass spectroscopic detection was used to characterize the bilberry extract and to measure uptake, transport, and metabolism in RPE cells. Results suggest that RPE cells internalize and metabolize anthocyanins. Although ineffective in preventing apoptosis, bilberry extract inhibited intracellular radical generation by as much as 60%. Western blot analysis revealed that physiological concentrations of bilberry anthocyanins up-regulate the oxidative stress protective enzymes heme oxygenase-1 (HO-1) and glutathione S-transferase (GSTP1) proteins in RPE cells by 1.5- to 2-fold over untreated cells in 6 hours and, at pharmacologic doses, up-regulate HO-1 as much as 10-fold over a 24-hour period. Bilberry anthocyanins and phenolics were shown to induced increases in HO-1 and GSTP1 messenger RNA. The observed increases were similar to that observed for protein. Bilberry anthocyanin induction of phase II detoxifying and oxidative stress protective enzymes suggest more significant protective effects than direct radical quenching suggesting these phytochemicals may thus enhance glutathione levels or altered cellular redox states.

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