CAROTENOLS AND OXYCAROTENOLS OF THE C40 SERIES 549 



Lycoxanthin forms a mono-acetate when treated with acetyl chloride in 

 pyridine (m.p., 137°C.) 



H,C CHj HjC ch, 



^ hhhIhhhIhhhhIhhhIhhh \ 

 hc c'c:c'c:c'c:c-c:c'c:c-c:c-c:c'c:c-c:c-g ch 



H\l II II I 



A .^v C CHe 



Hq/ \ / \ / \ / 



CHj HjC C 



Ht Hz 



Ljcoxanthiii 



HjC CH3 



HjC CH; 



C CHj CHj CH3 CHj ^c^ 



-^ HhhIhhhIhhhhIhhhIhhh \ 



HC C-c:c-c:C-c:c-c:C'C:C-C;C-C:C-C:C'C:C'C CH 



»\l II II l/H 



CO CO 



C CHj HjC C °^ 



Ljcophyll 



(^) Cryptoxanthin 



Cryptoxanthin, C4oH5eO, is the xanthophyll with the smallest proportion 

 of oxygen ; hence, of all the carotenols, it most nearly approaches /3-carotene 

 in properties. It was first isolated from Carica papaya (papaya) in 1933 by 

 Yamamoto and Tin,^* who gave it the name "caricaxanthin" and assigned 

 it an empirical formula of C40H56O2. The name "cryptoxanthin" was sug- 

 gested by Kuhn and Grundmann,-^^ who prepared the new carotenol from 

 the red calyx and berries of the Physalis alkekengi (strawberry or w^inter 

 ground-cherry) and likewise from the berries of Physalis francheti (Chinese 

 lantern plant). The latter workers also gave the correct empirical formula. 

 The identity of caricaxanthin and cryptoxanthin was established the follow- 

 ing year. '-^■- 



a. Structure. On catalytic hydrogenation, cryptoxanthin takes up 22 

 hydrogen atoms, which indicates the presence of 11 double bonds. It 

 contains one active hydrogen. The oxygen is present in a hydroxyl group, 

 as is proven by the acetylation which occurs in pyridine when the pig- 

 ment is treated with acetic anhydride. Cryptoxanthin acetate, C4oH550- 

 OCCH3, can be obtained in gamet-red leaflet-like crystals which melt at 

 117-118°C. Kuhn and Grundmann'-^^ first proposed the formula for 

 cryptoxanthin now known to be correct. This is based upon its provitamin 

 A activity, which predicates a /3-carotene structure on one side, while the 



260 R. Yamamoto and S. Tin, Bull. TnM. Phys. Chem. Research, 12, No. 3, 354-359 

 (1933); abstract in S,ci. Papers Inst. Phys. Chem. Research Tokyo, 20, No. 411-413, p. 22 

 (1933). 



«i R. Kuhn and C. Grundmann, Ber., 66, 1746-1750 (1933). 



2*2 P. Karrer and W. Schlientz, Helv. Chim. Acta, 17, 55-57 (1934). 



