Ascorbate-stimulated lipid peroxidation in human brain is dependent on iron but not on hydroxyl radical.

Lipid peroxidation has been postulated as a cause of neuronal damage in both aging and neurodegenerative disease. In studies of neurodegenerative disease, iron, iron plus ascorbate, or ascorbate alone has been used to stimulate lipid peroxidation. The mechanism by which ascorbate stimulates lipid peroxidation in human brain is unclear. The studies reported here were performed to determine whether ascorbate-stimulated lipid peroxidation in human brain membrane fragments was dependent on iron, superoxide radical, hydrogen peroxide, or hydroxyl radical. Our findings indicate that although ascorbate-stimulated lipid peroxidation in brain is iron dependent, it apparently does not require hydrogen peroxide or hydroxyl radical, but rather is dependent on superoxide radical formation.