IV. BIOCHEMICAL SYSTEMS 501 



logical response of ('aiefully controlled test animals to administration of 

 tocopherol preparations accor(lin,<>; io staiulaid procedures" is the ultimate 

 measure of potency and a desirable ([uaiity control test to be conducted on 

 composite production samples. 



IV. Biochemical Systems 



HENRY A. MATTILL 



A. ABSORPTION AND METABOLISM 



The absorption of tocopherols, like that of other fat-soluble substances 

 is greater from oil solution than from vegetable tissues.^ There is no evi- 

 dence that esterification is a feature of the absorption of vitamin E as it is 

 of vitamin A; indeed, when the ester is fed to rats, the serum contains the 

 free alcohol, suggesting rather rapid hydrolysis;- but only about half as 

 much tocopherol is found in the serum as when free tocopherol is given. The 

 rise in human serum was reported to be about the same after the ingestion 

 of either form.^ The presence of bile salts is essential; in rats'* and in dogs^ 

 with bile fistula the amount of tocopherol absorbed from a good diet was 

 sufficiently reduced to cause demonstrable deficiency. 



On a normal intake, absorption is fairly complete. After a daily dose of 

 3.5 mg. in a rat, 3 to 15 % of it appeared in the feces; after a large dose, as 

 much as 25 %.^ Its presence in the urine could be demonstrated only spec- 

 trophotometrically under those conditions but not chemically; also, no 

 tocoquinone was demonstrable.'' 



Methylation of any of the lower homologs to the trimethyl a variety is 

 unlikely in view of the appearance of 7-tocopherol in the eggs following the 

 feeding of it to laying hens.^- ^ The deposition in eggs after feeding the three 

 tocopherols was 10:2.5:1 for a\^\y. The feeding of a-tocopherol to milch 



" K. E. Mason and P. L. Harris, Biol. Symposia 12, 459 (1947). 

 ^ C. Engel and J. T. Heins, Acta Brevia Need. Physiol. Pharmacol. Microbiol. 13, 



37 (1943). 

 2 C. Engel, Acta Brevia Neerl. Physiol. Pharmacol. Microbiol. 11, 18 (1941). 

 ' E. L. Hove, Trans. 1st Conf. on Biol. Antioxidants, New York p. 51 (1946). 

 < J. D. Greaves and C. L. A. Schmidt, Proc. Soc. Expil. Biol. Med. 37, 40 (1937). 

 *K. M. Brinkhous and E. D. Warner, Am. J. Pathology 17, 81 (1941). 



8 W. F. J. Cuthbertson, R. R. Ridgeway, and J. C. Drummond, Biochem. J. 34, 

 34 (1940). 



7 L. R. Hines and H. A. Mattill, J. Biol. Chem. 149, 549 (1943). 

 * M. L. Quaife, W. J. Swanson, M. Y. Dju, and P. L. Harris, Ann. N. Y. Acad. Sci. 

 52, 300 (1948). 



9 x\I. Y. Dju, M. L. Quaife, and P. L. Harris, Am. J. Physiol. 160, 259 (1950). 



