Niki E, Noguchi N

Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology, Ikeda, Osaka 563-8577, Japan, and Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1, Komaba, Tokyo 153-8904, Japan.
Vitamin E is the major lipophilic, radical-scavenging antioxidant in vivo and protects humans from the oxidative stress mediated by active oxygen and nitrogen species. The mechanisms of the inhibition of oxidation by vitamin E in vitro are now fairly well understood, but the dynamics of antioxidant action of vitamin E in vivo have not been well elucidated yet, primarily because of the inherent heterogeneity of biological systems. In this Account, the factors which determine the antioxidant capacity of vitamin E are discussed, and the importance of its localization and mobility in the membranes and lipoproteins is emphasized.