TOCOPHEROLS IN VARIOUS METABOLIC PROCESSES 703 



chain has been broken down to a 7 lactone. This intermediate has the 

 structure shown below : 



CH, 



H3C CH3O CH3CH, C=0 



Derivative of a-Tocopherol Excreted in the Urine by Human Subjects and by Rabbits 

 after the Feeding of a-Tocopherol 62, 106a 



7. The Importance of Tocopherols (Vitamins E) in Various Metabolic Proc- 

 esses 



(1) Introduction 



The tocopherols play a unique role among the vitamins in that they are 

 implicated in a wide variety of actions. This would suggest that they are 

 concerned with some general key reaction which is common to most cells 

 and tissues of the body. One reaction which is generally recognized as the 

 most important single property of vitamin E is its antioxidant action, 

 which functions both in vivo and in vitro. However, according to Harris 

 and Mason, ^- a number of functions of vitamin E cannot be ascribed to its 

 antioxidant nature, and are quite specific in character for a-tocopherol as, 

 for example, its function in assisting in the normal resistance of the red 

 blood cells to hemolysis. Although there are no convincing data which 

 prove that vitamin E is essential for the formation or maintenance of a 

 specific enzyme or coenzyme, or that it functions as a coenzyme, either of 

 these functions might well be considered to be an additional activity over 

 and above its antioxidant action. 



Many of the deficiency symptoms resulting from an absence of vitamin 

 E from the diet are irreversible. The deficiency of vitamin E may bring 

 about irreversible muscle degeneration. Vitamin E added to the diet does 

 not result in any reparative or curative action on the muscle fibers which 

 have started to die. Any beneficial effect which is noted under such condi- 

 tions, due to vitamin E therapy, is attributable to the changes in the 

 proportions of regenerating and degenerating fibers, and also to the altera- 

 tion in the relative speed of regeneration and degeneration. Other ex- 

 amples of the irreversibility of damage due to vitamin E deficiency include 

 testicular degeneration in the male vitamin E-deficient rat, the fatal effect 

 of encephalomalacia in the chicken if vitamin E therapy is not initiated 



