Vitamin E Promotes the Inverse Hexagonal Phase via a Novel Mechanism: Implications for Antioxidant Role

Abstract

Vitamin E (alpha-tocopherol) protects polyunsaturated membrane phospholipids from oxidation. How it accomplishes this task at relatively low concentrations is an ongoing area of investigation. An interesting property of alpha-tocopherol is that it promotes the inverse hexagonal (HII) phase in PE membranes. It has been well established that other compounds, such as dodecane and similar purely hydrophobic compounds, promote the HII phase by relieving extensive stress. We argue that alpha-tocopherol promotes the HII phase by a novel mechanism, by instead relieving compressive stress. With this new understanding, we examine the hypothesis that alpha-tocopherol will preferentially partition close to polyunsaturated lipids to maximize its effectiveness as an antioxidant.