550 VI. CAROTENOIDS AND RELATED COMPOUNDS 



other half of the molecule corresponds to that of a similar portion of a 

 zeaxanthin molecule. 



HjC CHj H 3C CHj 



Q CHj CHj CH3 CHj Q 



y \ hhIhhhIhhhhIhhhIhh /\ 

 HsC C'C:C'C:C'C:C'C:C'C:c-c;C'C:c-c:c-c:c-c chz 



/ 



HiC C C C 



\ / \ / \ / ^OH 



C CHj HjC C 



H2 Hz 



Cryptoxanthin 



b. Occurrence. Because of the i)resence of the alcohol group in the 

 molecule, cryptoxanthin generally occurs as the ester. This is true not 

 only in the case of Physalis alkekengi and P. franchettP^^ but also in the 

 papaya {Carica papaya). "^^^ Cryptoxanthin occurs in a number of fruits, 

 including those of Arbutus unedo (strawberry tree),^^^ Diospyros costata 

 (persimmon), 2^^ Citrus poonensis,^^^ and in orange peels. ^^^'-^^ The 

 carotenol is also reported in Mediterranean mandarines (Citrus maduren- 

 sis).^^'^ Other sources are the red berries of the false bittersweet {Celastrus 

 scandens) ,^^^ paprika husks (Capsicum frutescens),^^ yellow corn (Zea 

 mays),^^^ and the flowers of Cucurbita pepo (pumpkin). ^^^ 



Cryptoxanthin is a component of the flowers of the silk oak (Grevillea 

 robusta Cunningham) ,^^ the monkey flower (Mimulus longiflorus Grant)," 

 and perhaps of the sunflower (Helianthus annuus).'^^^ It has been reported 

 as a pigment in the pennate marine diatom, Nitzschia closterium,^^'^ and 

 in the timothy bacillus (Mycobacterium phlei)^^^ 



The presence of cryptoxanthin in animal products may probably be ex- 

 plained in the same way as in the case of lycopene, i.e., that it is obtained in 

 the food. Thus, it has been found in butler,^^® eggs,'^^ and in the blood 

 serum of cattle.'-''^ Cryptoxanthin has been shown to act as a provitamin A 



2=3 K. Schon, Biochem. J., 29, 1779-1785 (1935). 



25* R. Yamamoto and S. Tin, Bull. Inst. Phys. Chem. Research, 12, No. 5, 437-440 

 (1933); abstract in Sci. Papers Inst. Phi/s. Chem. Research Tokyo, 21, No. 422-425, 

 abstr. p. 25 (1933). 



25* L. Zechmeister and P. Tuzson, Ber., 6<J, 1878-1884 (1936). 



256 p. Kaner and E. Jucker, Helv. Chim. Acta, 27, 1695-1696 (1944). 



2" L. Zechmeister and P. Tuzson, Z. physioI. Chem., 240, 191-194 (1936). 



258 L. Zechmeister and L. v. Ciiolnoky, Ann., 509, 269-287 (1934). 



259 R. Kuhn and C. Grunilmann, Ber., 67, 593-595 (1934). 



260 L. Zechmeister, T. Beres, and E. Ujhelyi, Ber., 68, 1321-1323 (1935). 



261 L. Zechmeister and P. Tuzson, Ber., 67, 170-173 (1934). 



262 N. Pace, J. Biol. Chem., I40, 483-489 (1941). 



263 M. A. Ingraham and li. Steenbock, Biochem. J., 29, 2553-2562 (1935). 

 26* A. E. Gillam and I. M. Heilbron, Biochem. J., 29, 1064-1067 (1935). 

 265 A. E. Gillam and AI. S. El Ridi, Biochem. J., 29, 2465-2468 (1935). 



