II. CHEMISTRY 485 



Another approach to the understanding of its chemistry was opened by 

 the observations that diets ordiiuirily adecinate for reproduction gave 

 sterile animals if the diets contained certain fats which readily become 

 rancid or if the usual mixed diets were treated with ethereal ferric chlo- 

 ride.*""" From the nnsaponifial>le portion of several vegetable oils and plant 

 extracts concentrates were prepared''' which contained antioxidants (called 

 inhibitols'^ because of the presence of o- or p-hydroxyl groups) and also 

 vitamin E/"- '^ as judged by bioassays. 



From these observations, either of two conclusions could be drawn: (1) 

 that vitamin E was readily oxidized and was protected by the accompany- 

 ing antioxidants, or (2) that the vitamin and the antioxidant were the 

 same substance. The latter view was favored by the fact that the two could 

 apparently not be separated, but it was not acceptable because the biologi- 

 cal and antioxygenic activities were not parallel from one concentrate to 

 another. The uncertainty and confusion were resolved by the demonstra- 

 tion*^ that there were several substances with unequal vitamin E activity 

 and whose antioxygenic action also varied but in the opposite direction. 



The several kinds of vitamin E have been shown to be the principal 

 antioxygenic components of natural fats, and their possible function as 

 "biological antioxidants" has been the subject of many discussions and 

 publications.^" 



The parallel observations on the vitamin E and the antioxidant content 

 of concentrates^* confirmed the earlier findings of Evans and Burr^ except 

 for the biological inactivation of vitamin E by acetylation; the presence of 

 a hj'droxyl group was demonstrated, and the benzoic acid ester as well as 

 the acetylated compound was shown to be biologically active. A previously 

 observed band in the ultraviolet spectrum with maximum at 2940 A. was 

 believed not to be related to vitamin E,-- since concentrates from other 

 sources, such as palm oil, showed the same band but were biologically 

 inactive. 



'0 L. T. Anderegg and V. E. Nelson, Ind. Eng. Chem. 18, 620 (1926); V. E. Nelson, 

 R. L. Jones, G. Adams, and L. T. Anderegg. ibid. 19, 840 (1927). 



" H. M. Evans and G. O. Burr, /. Am. Med. Assoc. 88, 1462 (1927). 



'2 H. A. Mattill, /. .4m. Med. Assoc. 89, 1505 (1927). 



" J. Waddell and H. Steenbock, /. Biol. Chem. 80, 431 (1928). 



»^ M. W. Taylor and V. E. Nelson, Proc. Sac. Exptl. Biol. Med. 27, 764 (1930). 



15 H. S. Olcott and H. A. Mattill, J. Biol. Chem. 93, 59, 65 (1931); J. Am. Chem. Soc. 

 58, 1627 (1936). 



•" H. A. Mattill, J. Biol. Chem. 90, 141 (1931). 



17 H. S. Olcott and H. A. Mattill, /. Biol. Chem. 104, 423 (1934). 



•8 H. S. Olcott, J. Biol. Chem. 107, 471 (1934). 



'9 H. S. Olcott and O. H. Emerson, /. Am. Chem. Soc. 59, lOOS (1937). 



-"Trans. Ist-Slh Confs. on Biol. Antioxidants, New York- (1946-1950). 



2' H. S. Olcott, ./. Biol. Chem. 110, 695 (19.35). 



" A. J. P. Martin, T. Moore, M. Schmidt, and F. 1'. Bowden, Nature 134, 214 (1934). 



