TOrOPHKROLS IX VARIOUS MKTAROLIC PROCESSES 739 



Moore^'^ and Bacharach^''^ are generally credited with the disco\'ery that 

 vitamin E potentiates the action of vitamin A. It was found that the 

 vitamin A reserves in the livers of rats kept for a long inter\'al on xitamin 

 E-deficient diets had a much lower concentration of vitamin A than 

 occurred in this organ when the rats received adequate vitamin E. Quack- 

 enbush and associates^^^ demonstrated that a-tocopherol prevented the 

 autoxidation of carotene in vitro. It was likewise obser^'ed that tocopherol 

 augmented the growth response of vitamin A-deficient rats to minimum 

 quantities of carotene. Hickman and co-workers "^^ also arrived at the 

 same conclusion, namely that a-tocopherol has the power to augment the 

 A \'itamins. The interaction was referred to by this group^-" as a "sparing" 

 or "synergistic" action, or better as "co-idtamin E" acti\^t^^ Hickman 

 et al.*~^ reported that the natural vitamin E (mixed tocopherols) enhanced 

 the grow^th-promoting action of vitamin A alcohol, vitamin A acetate, and 

 U.S. P. vitamin A reference oil. Moreover, it was observed that a longer 

 interval was required to deplete young rats of vitamin A in the presence 

 of tocopherols. The .surAa\'al time was also increased w^hen a given dosage 

 of vitamin A was administered to \itamin A-deficient rats if they also 

 received vitamin E. Harris and co-workers^-^ reported that a-tocopherol 

 potentiated the ^^tamin A-like action of carotene; approximately 0.5 mg. 

 of the natural mixed tocopherols was found to afford maximum protection. 

 In a fui'ther simultaneous report of this group, ^-- it was further recorded 

 that the three tocopherols (a-, ^-, and 7-) were equally effective in sparing 

 vitamin A. This is in contradistinction to their effect as antisterility 

 agents; in this respect the a-form was the most potent and 7-tocopherol 

 was the weakest. Their acti\aty was augmented slightly by mutual 

 admixture, and especially by the addition of selected antioxidants. Toco- 

 quinone is as effective as tocopherol in sparing carotene. Since the 

 carotene content of the feces was markedly increased when tocopherols 

 were given, it is postulated that tocopherols exert their beneficial effect 

 in controlHng the oxidative changes in the intestine. •^^- The ineffective- 



"«T. Moore, Biochem. J., S4, 1321-1328 (1940). 



<" A. L. Bacharach, Quart. J. Pharrn. Pharmacol, 13, 138-149 (1940). 



*i8 F. W. Quackenbvish, R. P. Cox, and H. Steenbock, /. Biol. Chem., 145, 169-177 

 (1942). 



^>« K. C. D. Hickman, P. L. Harris, and M. R. Woodside, Nature, 150, 91-92 (1942). 



«oK. C. D. Hickman, M. W. Kalev, and P. L. Harris, J. Biol. Chem., 152, 303-311 

 (1944). 



«i P. L. Harris, M. W. Kaley, and K. C. D. Hickman, ./. Biol. Chem., 152, 313-320 

 (1944). 



^22 K. C. D. Hickman, M. W. Kalev, and P. L. Harris, ./. Biol. Chem., 152, 321-328 

 (1944). 



