SHANGHAI—Alpha-tocopherol may help eye health by protecting retinal pigment cells from oxidative stress and serving as a phase II enzyme inducer, according to research from the Chinese Academy of Sciences (J Nutr Biochem. ePub Feb. 12, 2010). Scientists investigated whether alpha-tocopherol in a human retinal pigment epithelial (RPE) cell line could induce Phase II enzyme activity and protect against oxidative toxicity induced by acrolein, a major component of cigarette smoke and product of lipid peroxidation. Introducing acrolein to the cell lines caused significant loss of cell viability, increased oxidative damage, decreased antioxidant defenses, inactivated the Keap 1/Nrf2 pathway, and impaired mitochondrial function.
Pretreating the cells with alpha-tocopherol increased Nrf2 expression, as well as expression or activity of several Phase II enzymes including glutamate cysteine ligase, glutathione S-transferase and superoxide dismutase. The enhanced antioxidant defenses protected the RPE cells from the adverse effects seen when acrolein was introduced to the un-treated cells. Researchers concluded alpha-tocopherol not only helps serve as a direct antioxidant against cellular toxicity in eye cells, but also induces endogenous antioxidant defenses.
