Quantification of the Suppressive Effects of Flavonoids on the Cytotoxicity of Linoleic Acid Hydroperoxide

found in abundance in food and drinks and are consumed. They have recently attracted much attention because of their broad pharmacological activities, in particular antioxidant activities. Reactive oxygen species-induced oxidative stress is suggested to play important roles in the etiology of neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease, which are intimately associated with neuronal death. If the oxidative stress is suppressed by dietary factors such as flavonoids, this group may serve as a preventive against neurodegenerative diseases. It is of great interest, therefore, to see whether or not flavonoids can prevent neuronal cells from being damaged by reactive oxygen species. LOOH is a highly cytotoxic lipid peroxide and also a reactive oxygen species. PC12 cells are grown in a serumcontaining medium, and attain the phenotypic properties of sympathetic neurons upon addition of the nerve growth factor. Thus, the PC12 cell line is used as a model system of neuronal cells. Using LOOH as a toxic reactive oxygen species, we examined the suppressive effect of flavonoids on reactive oxygen species-induced cytotoxicity toward PC12 cells.