552 VI. CATIOTENOIDS AND RELATED fOMPOUNDS 



(c) Cryploxanthin Di-epoxide, C40H86O3. In addition to the mono- 

 epoxide, the di-epoxide is hkewise formed on the oxidation of ciyptoxanthin 

 acetate with perphthallic acid.-^^ It can be crystalhzed from a mixture of 

 benzene and petroleum ether (m.p., 194°C.). When treated with con- 

 centrated hydrochloric acid, the di-epoxide gives a deep blue coloration 

 which is permanent over a long period. 



CH5 CH, CH, CH, 



C CH3 CH3 CH3 CH, ^c'^ 



/ \ I I I I / \ 



HjC C-CH : CH • C : CHCH : CH ■ C : CHCH : CH CH : C • CH : CHCH : C • CH : CH ■ C CH, 



I I I l/H 



HjC C-^ ^C C 



CHj H3C C 



Hz Hj 



Crj'ptoxanthin di-epoxide 



(d) Cryptochrome, C40H56O3. When cryptoxanthin di-epoxide is treated 

 with chloroform containing hydrochloric acid, the difuranoid compound 

 cryptochrome is formed. This compound has not been crystallized. 



HjC CHj HjC CHj 



\ / \ / 



c c 



/ \ / \ 



HjC C=CH HC=C CH2 



ICH5 CH3 CHs CHj 



I I IhhhIhhhhIhhhI I I l/H 



HjC c ch-c: c- c: C' c: c • c:c- c; c- c: c • c: c — ch c c 



"^ CH3 H^c"^ "^ 



Cryptochrome 



(e) Cis-Trans Isomers. Zechmeister and Lemmon^^^ have described a 

 number of cis isomers of cryptoxanthin which are designated as neocrypto- 

 xanthin U, neocryptoxanthin A, and neocryptoxanthin B. The absorption 

 peaks are at somewhat shorter wave lengths than the corresponding ones 

 of all-iraws-cryptoxanthin. 



(3) Rubixanthin 



Kuhn and Grundmann'^^--^ were the first to report the presence of an 

 isomer of cryptoxanthin in the rose hips of Rosa canina (dog rose), R. 

 eglanteria (sweetbriar rose), and R. damascena (damask rose). 



Rubixanthin has an empirical formula of C4nH560. In contradistinction 

 to other xanthophylls, rubixanthin absorbs 12 molecules of hydrogen on 

 catalytic hydrogenation. It also yields one mole of acetone on ozonization. 

 These two reactions are in harmony with those given by 7-carotene, and 

 indicate that the compound possesses only a single /3-ionone ring. The 

 oxygen is present in a hydroxyl group. Since the carotenol is biologically 



"1 L. Zechmeister and R. M. Lemmon, J.Am.Chem. Soc, 66, 317-322 (1944). 



OH 



