TOCOPHEROLS IN VARIOUS METABOLIC PROCESSES 723 



c'. Antid^'strophic Agents: a-Tocopherol has long been recognized 

 because of its abilitj^ to correct muscuiai' dystrophy, and two deri\'atives 

 also function in this capacity. Thus, a-tocopherylhj^droquinone, which is 

 believed to be an intermediate of a-tocopherol, is a potent antidystrophic 

 compoimd, but has no antisterilitj' acti\'ity.^-^'-^^ Mackenzie and iMacken- 

 zie^-^ demonstrated that it undergoes little or no conversion to a-tocopherol 

 in vivo. A second compound, also recognized as an intermediate of a- 

 tocopherol and as closeh' related to a-tocopherylhydroquinone, namely, 

 a-tocopherylquinone (or a-tocoquinone) has been fomid to be active as an 

 antidystrophy agent; it possesses no antisterility effect. -^^ The hydroxy- 

 (luinone of a-tocopherol was found by Wright and Drunnnond'-^'* to be 

 without biologic effect in the case of pregnant rats on a vitamin E-deficient 

 diet. In addition to the results of the Mackenzie group, which were 

 obtained on the rabbit, and which have been confirmed by Farber, Milman, 

 and ]\Iilhorat-^^ on this species, a similar antid\^strophic effect is exerted 

 b}' the hydroquinone or quinone, or both, in the case of the hamster^^^ 

 and the calf."^ Blaxter et al.-^^ found that a-tocopherol acetate also pre- 

 vented muscular dystrophy in the calf. It is suggested^^'^^^ that a- 

 tocopherol, the antisterility \'itamin, maj^ at the same time be a provitamin 

 for other compounds which function as antidystrophic agents. For the 

 structure of these compounds, see page 702. In addition to the tocopherol 

 hitermediates, methjdene blue has been found to be effective in counter- 

 acting the effects of muscular dystrophy. For a summarj' of this inter- 

 esting action of methylene blue and of other redox components, the reader 

 is referred to page 740. 



e. The Role of Vitamin E in Relation to Smooth Muscle. When rats 

 are deprived of vitamin E for several months, organs containing smooth 

 muscle develop a chestnut brown coloration which becomes darker as the 

 deficiency progresses. This discoloration is due to the deposition of acid- 

 fast pigment granules in the smooth muscle cells, and of macrophages in the 



28' A. Issidorides and H. A. Mattill, ./. Biol. Chem., 188, 313-316 (1951). 



290 M. D. Wright and J. C. Drummond, Biochem. J., 34, 32-33 (1940). 



291 M. C. Farber, A. E. Milman, and A. T. Milhorat, Z. physiol. Chem., 295, 318-323 

 (1953). 



"2 K. L. Bla-xter, F. Brown, W. A. Wood, and A. W. MacDonald, Brit. J. Nutrition, 7, 

 337-349 (1953). 



