[15] High-Performance Liquid Chromatography Methods for Vitamin E in Tissues

Abstract

Free radical-catalyzed lipid peroxidation is a continual biological process, which if unchecked may cause damage to cellular and intracellular membranes, resulting not only in changed membrane structure but also in the destruction of the functional integrity of membrane-bound enzymes. Vitamin E, alone and in concert with the selenium-containing enzyme, glutathione peroxidase, can inhibit this process. This function of vitamin E may be aided by a specific physicochemical interaction between the phytyl side chain of α-tocopherol and the fatty acyl chains of polyunsaturated phospholipids, particularly those derived from arachidonic acid, by providing a mechanism for anchoring vitamin E to membranes and facilitating the antioxidant behavior attributed to α-tocopherol. Other consequences could be a reduction in permeability of biological membranes containing relatively high levels of polyunsaturated fatty acids, particularly arachidonic acid and the prevention of the degradation of membrane phospholipids by membrane-bound phospholipases in vivo. In recent years, a variety of methods have appeared in the literature for the high-pressure liquid chromatography (HPLC) determination of tocopherols in biological samples. Many of these have concerned themselves primarily with α-tocopherol, and serum or plasma has been the most frequently used form of sample. For the determination of α-tocopherol, both normal and reverse phase methods have been successfully used. This chapter presents a sensitive, rapid method suitable for the extraction and determination of tocopherols in a range of small-tissue samples. © 1984, Elsevier Inc. All rights reserved.