Relative Importance of Vitamin E in Antiperoxidative Defenses in Human Blood Plasma and Low-Density Lipoprotein (LDL)

Human blood plasma contains an array of nonenzymatic low-molecular-weight antioxidants. These antioxidants can be classified into two groups: the water-soluble antioxidants present in the aqueous phase of plasma and the lipid-soluble antioxidants associated with lipoproteins. The relative importance of an individual antioxidant in a biological system, such as plasma or low-density lipoprotein (LDL), depends on both the nature of the oxidant stress imposed on the biological system and the type of target molecule to be protected from oxidative damage, for example lipids, proteins, or nucleic acids. This chapter reviews data on the potency of vitamin E relative to the potency of other antioxidants naturally present in human plasma and LDL to prevent peroxidative damage to lipids. An important implication of the oxidative theory of atherosclerosis is that antioxidants which can effectively prevent peroxidative damage to LDL lipids may act an antiatherogens.