Molecular pharmacology of vitamin E: structural aspects of antioxidant activity.

In this review, the involvement of vitamin E in free radical physiology and antioxidant mechanisms is discussed. Moreover, structure-activity relationship (SAR) studies on vitamin E analogues are presented. A molecular explanation for the antioxidant activity often is based on molecular parameters, such as Hammett sigma and Brown sigma +. These parameters correlate with the activity. Using semiempirical calculations, we have found other molecular parameters related to electron distribution and structure (such as the difference in heat of formation between the compound and its radical or the energy of the highest occupied molecular orbital, HOMO) which correlate with the antioxidant action of vitamin E and its derivatives.