50 VITAMINS A AND CAROTENES 



that of the all-traiis vitamin Ai (p. 31). The biopoteney of anhydrovita- 

 min A is about 17,000 I.U. per gram and may not be significant in view of 

 its conversion by the rat to rehydrovitamin A.^'^ 



Prolonged treatment of vitamin A with ethanolic hydrogen chloride gives 

 isoanhydrovitamin A/^^*^- "^- '^^ which also shows a fine structure in the 

 ultraviolet with maxima at 300, 347, and 307 m/x, and with -fi'l^m. values 

 of 1100, 1360, and 1100, respectively. The antimony trichloride color shows 

 a maximum at 620 m/x with an £'}^''m. value of 3200. The biological activity 

 of isoanhydrovitamin A is of the same order of magnitude as that of an- 

 hydrovitamin A. A product which contains chlorine was also isolated.^^" 



An isomer, XCV, of anhydrovitamin A, named axerophthene, was syn- 

 thesized by Karrer and Benz^*' from C is- ketone and ethyl magnesium 



H3C CH3 ^jj^ ^^^ 



I I 



CH=CH— C=CH— CH=CH— C=CH— CH3 



\ / — CH3 



XCV Axerophthene 



bromide. This also has a fine structure in the ultraviolet with maxima at 

 331, 346, and 364 m/x, and with /i'}^^„. values of 1080, 1260, and 952, re- 

 spectively. The antimony trichloride color shows two maxima at 474 and 

 577 m/x, respectively. The biopoteney of this hydrocarbon is about 0.1 that 

 of vitamin A.^^- 



7. Vitamin A 2 



a. Isolation 



When fresh-water fish liver oils were examined by means of the Carr- 

 Price reaction, two well-defined maxima were observed: one at 620 m/x at- 

 tributed to vitamin Ai, and another at 693 m/i which was assigned to a new 

 vitamin labeled vitamin A2.^^'' ^^^ Although the vitamin has been isolated 

 in the pure form from selected pike liver oils,^*^ it has not yet been crystal- 

 lized. The ultraviolet spectrum of vitamin A2 as compared with that of 

 vitamin Ai is shown in Fig. 11. Table XIV shows some of the properties of 

 vitamin A2 and some of its derivatives. 



1" E. M. Shantz, J. Biol. Chem. 182, 515 (1950). 



180 p Meunier, A. Gu^rillot-Viriet, J. Jouaiineteuu, and M. Gourovitch, Compt. rend. 



226, 128 (1948). 

 1" P. Karrer and J. Benz, Hdv. Chim. Acta 31, 1048 (1948); 32, 232 (1949). 



182 H. von Euler and P. Karrer, Helv. Chim. Acta 32, 461 (1949). 



183 E. A. Lederer and V. A. Rozanova, Biok-himii/a 2, 293 (1937). 



184 A. E. Gillam, I. Heilbron, W. E. Jones, and E. Lederer, Biochcm. J. 32, 405 (1949). 

 186 E. M. Shantz, Science 108, 417 (1948). 



