804 IX. THE VITAMIN E GROUP 



been reported by several authors^'*' ^^^-^g^ gjniiiar low values have been 

 noted for lard^^"- ''^'^•, in one sample with a total of 2.7 milligram per cent, 

 2.3 mg. was a-tocopherol, and 0.4 mg. consisted of the 7-form.'^^'^ A com- 

 pilation of the tocopherol content of a wide variety of animal and vegetable 

 products, and of many animal tissues, has recently been prepared by 

 Lange.^^-'^ 



The tocopherol content of animal fat can be increased when a generous 

 amount of this vitamin is included in the diet. Lundberg and associates^" 

 found that, whereas rendered body fats of rats which had been raised from 

 weaning to 100 days on a diet free from vitamin E were abnormally suscep- 

 tible to oxidation, ^^ the addition of a single dose of a-tocopherol to the diet 

 restored the stability of body fats to their normal value. The maximum 

 deposition of a-tocopherol in the abdominal fats is not reached until 7 to 10 

 days after the feeding of a single 50-mg. dose. The quantities of a-toco- 

 pherol deposited in the abdominal fats increase in proportion to the amount 

 fed, up to a maximum single dosage of 500 mg. Barnes et al.^^ were unable 

 to cause the deposition of antioxidants other than tocopherol when such 

 substances were introduced in the diet. 



3. Structure of the Tocopherols 



(1) a-Tocopherol 



a-Tocopherol, or better 5,7,8-trimethyltocol, has the empirical formula of 

 C29H50O2, and has now been proved to have the structure shown in (I). 



I ' Ha 

 H0C6 C'o ^CHj 



HjCa /b 'C-CHzCHzCHaCH CHzCHzCHzCH CHzCHzCHaCHCH, 

 ^C ^0^ CH, CH, CH, CH, 



CH, 



I 



"*■ A. Emmerie and C. Engel, Z. Vitaminforsch., 13, 259-266 (1943); Chem. Zentr., 

 1943, II, 1974. Cited by W. Lange, /. Am. Oil Chemists' Soc, 27, 414-422 (1950). 



"-^ P. L. Harris, M. L. Quaife, and W. J. Swanson, J. Nutrition, 40, 367-381 (1950). 



""^ P. L. Harris, W. J. Swanson, and K. C. D. Hickman, /. Nutrition, S3, 411-427 

 (1947). 



"' H. Lieck and H. Willstaedt, Si'ensk'Kem. Tid., 57, 134-139 (1945); Chem. Abst., 

 40, 4759 (1946). 



"^ W. Lange, /. .4m. Oil Chemists' Soc, 27, 414-422 (1950). 



80 W. O. Lundberg, R. H. Barnes, M. Clausen, and G. O. Burr, J. Biol. Chem., 153, 

 265-274 (1944). 



81 R. H. Barnes, W. O. Lundberg, H. T. Hanson, and G. O. Burr, ./. Biol. Chem., 149, 

 313-322 (1943). 



