502 THE TOCOPHEROLS 



COWS (10 g. daily) raised the tocopherol content of the milk to 0.068 mg. 

 per gram of fat (from 0.025), whereas a mixture of 7- and 5-tocopherols 

 changed it to 0.034 mg. per gram of fat (from 0.022). Studies on normal 

 adults confirmed this idea; a-tocopherol increased the level of serum to- 

 copherols more quickly and for a longer time than 7. There appears to be 

 a selective deposition of a-tocopherol in animal tissues and fluids. 



The catabolic pathway is not known, but presumably it is via tocoph- 

 erylquinone, the first stable oxidation product; more of this than of 

 tocopherol was reported in dog plasma.^'' It has recently been found in the 

 stools,^^ but it was not demonstrable in rat liver, muscle, or urine.'^ 



The presence of some tissue tocopherol in a bound form has been in- 

 feried from the additional amounts variably obtained by acid alcohol ex- 

 traction, after the usual treatment with alcohol-petroleum ether (Skel- 

 lysolve B) mixture.^' ^^ Furthermore, the normal plasma content (0.9 to 

 1.2 mg. %) is only slowly extracted by ether or hydrocarbon solvents, 

 whereas prior or simultaneous use of ethyl alcohol rapidly extracts it;^^ 

 measurements of intrinsic viscosity and other evidence favor the view that 

 conjugates are formed with native proteins, most successfully with lipid- 

 free bovin plasma albumin, such that a concentration of 2 to 3 mg. of to- 

 copherol per milliliter of a 2 % protein solution can be readily achieved as 

 a stable slightly opalescent solution. The advantages of this procedure 

 over the use of the unphysiological phosphate or succinate are obvious. 



B. STORAGE 



The capacity of various rat tissues to accumulate tocopherol was first 

 demonstrated by Mason'^ in extensive trials with the bioassay method. 

 When the diet contained minimal amounts of vitamin E the liver stored 

 one-half to one-fourth as much as the skeletal muscles, body fat, and visceral 

 organs. With a high intake, the liver stored 14 times as much as at the lower 

 intake, the other tissues only 3 to 4.5 times. The liver is thus the chief re- 

 pository of vitamin E when its intake is high, and the amount found there 

 may be the best index of previous intake. 



C. ANTIOXYGENIC ACTION 



1. In Vivo 



Because of the increased stability of fats containing vitamin E, the pos- 

 sibility of enriching the fat stores by adding tocopherols to the diet has 



10 J. V. Scudi and 11. P. Buhs, J. Biol. Chem. 146, 1 (1942). 



11 H. Rosenkrantz, A. T. Milhorat, and M. Farber, J. Biol. Chem. 192, 9 (1951). 



12 H. Kaunitz and J. J. Beaver, /. Biol. Chem. 166, 205 (1946). 



13 S. R. Ames and H. A. Risley, Ann. N. Y. Acad. Sci. 52, 149 (1949). 

 1^ K. E. Mason, J. Nutrition 23, 71 (1942). 



