176 CAROTENOIDS CONTAINING HYDROXYL GROUPS XI 



Source References 



Iris of chicks L. Busch and H. J. Neumann, N atiirwissenschaften 



29 (1941) 782. 

 Mycobacterium phlei M. A. Ingraham and H. Steenbock, Biochem. J. 2g 



(1935) 2553. 



Nitzschia closierium Nello Pace, /. biol. Chem. 140 (1941) 483. 



Orange peels L. Zechmeister and P. Tuzson, Ber. 6g (1936) 1878. 



— P. Karrer and E. Jucker, Helv. chim. Acta 2y 



(1944) 1695. 

 Phy sails Alkekengi and 



Physalis Franchetii R. Kuhn and C. Grundmann, Ber. 66 (1933) 1746. 



Tangerines L. Zechmeister and P. Tuzson, Z. physiol. Chem. 240 



(1936) 191. 



Zea Mays R. Kuhn and C. Grundmann, Ber. 6y (1934) 593. 



Preparation^ 



Dried physalis cups are finely ground and extracted with methanol to remove 

 resinous materials. The cup meal is then continuously extracted with benzene at 

 room temperature. Most of the solvent is removed in vacuum and the residue which 

 contains zeaxanthin and cryptoxanthin esters is saponified at room temperature 

 with alcoholic potassium hydroxide. After about 15 hours, petroleum ether is added 

 to the solution, followed by distilled water until the zeaxanthin precipitate begins 

 to become resinous. The petroleum ether-benzene layer contains cryptoxanthin 

 which is isolated by adsorption on alumina. The pigment is purified by crystalli- 

 sation from a mixture of benzene and methanol. The yield amounts to about 100 

 mg pure cryptoxanthin from 1600 cups. 



Chemical Constitution 

 CHo CHo CHo CHo 



01i<. Cxi.j CHo OHo G 



/\ \ \ \ \ /\ 



CH2 C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CH=CHCH=C-CH=CH-C CHj 



HOCH C-CHj HsC-C CHg 



\^ / Cryptoxanthin \ / 



CHj CHg 



The constitution of cryptoxanthin was elucidated mainly by Kuhn and 

 Grundmann^. On hydrogenation, the pigment takes up 11 mols of hydrogen. 

 It therefore contains 11 double bonds and 2 isocyclic rings. The spectral 

 properties correspond to those of ^-carotene and indicate that all the 11 double 

 bonds are conjugated. Cryptoxanthin gives exactly i mol of methane with 

 methyl magnesium iodide, indicating the presence of i hydroxyl group. This is 

 confirmed by the formation of a monoacetate. The position of the hydroxyl 

 group could not be determined with certainty, but by analogy the 3-position 

 References p. 214— 2iy. 



