CAROTEN'OLS AND OXYOAROTENOLR OF THE C^ SERIES 551 



in rats. -*'"'■*• -*'^ Recent studies have indicated that the biological potency 

 somewhat exceeds 50% of that of /3-carotene (54, 59, and 60%). ^^^-^^^ 



c. Related Compounds, (a) Cryptoxantkin Monn-epoxide, C40H56O2. 

 This mono-epoxide is prepared-*" by the action of perphthalic acid on 

 cryptoxanthin acetate. Since its derivative cryptoflavin is entirely inac- 

 tive as a provitamin A, even in large doses,"" it is believed that both ionone 

 rings are substituted. 



h5c ch3 h.c ch. 



/\ hhIhhhIhhhhIhhhIhh ,'\ 

 HjC c-c:c-c:C-C:C'C:C-c:C-C:C-C:C-C:C-c:C-C CH: 



I l> II l/H 



HzC C C C 



\ / \ / \ / ^OH 



C CHj HjC C 



Hj Hj 



Cn'ptoxanthin inono-epoxide 



The solubility pattern of the mono-epoxide is similar to that of cryptoxan- 

 thin. When crystallized from a mixture of benzene and methanol, it forais 

 needles or platelets which melt at 154°C. When an ethereal solution of the 

 mono-epoxide is shaken with concentrated aqueous hydrochloric acid, a 

 transitory blue color formation takes place. 



(6) Cryptoflavin, C40H56O2. When this mono-epoxide is treated with 

 mineral acid, it is changed to the furanoid derivative cryptoflavin. ^^^ This 

 compound is biologically inactive."" When crystallized from a mixture of 

 petroleum ether and benzene, cryptoflavin forms leaflets having a strong 

 surface gloss. These melt at 171 °C. Cryptoflavin gives the same color 

 reaction with hydrochloric acids as does the mono-epoxide. 



H3C CHj 



\ / 



C^ H3C CHj 



/ \ \ / 



HzC C^CH CHj CHj CH3 CH3 C 



I I I IhhhIhhhhIhhhIhh /\ 

 HeC C CH— c: C • C : C • C : C • C : C • C: C • C: C • C: C • C : C' C CHz 



\c/\V II 1/" 



H2 rw C C 



H3C C °" 



Hz 



Cr.\-ptoflavin 



=«6 G. S. Fraps and A. R. Kemmerer, Ind. Eng. Chem., Anal. Ed., 13, 806-809 (1941). 



2*' H. J. Deuel, Jr., E. R. Meserve, C. H. Johnston, A. Polgdr, and L. Zechmeister, 

 Arch. Biochem., 7, 447-450 (1945). 



268 H. J. Deuel, Jr., S. ]M. Greenberg, E. Straub, T. Fukui, A. Chatterjee, and L. Zech- 

 meister, Arch. Biochem., 23, 239-241 (1949). 



26' P. Karrer and E. Jucker, Helv. Chim. Ada, 29, 229-233 (1946). 



2™ H. V. Euler, P. Karrer, and E. Jucker, Heh. Chim. Acta, 30, 1159-1160 (1947). 



