CAKOTENOLS AN'D OXYCAROTENOLS OF THE C40 SERIES 553 



inactive, it may be concluded that the hydroxy! is joined to the cychc por- 

 tion of the molecule rather than to the acyclic chain. 



HjC CH3 H jC CHj 



r CH3 CH3 CHj CHi Q 



/\ hhIhhhIhhhhIhhhIhhh "^ 

 HzC C-c:c-C:C-c:C'C:C'C:C-C:C-C:C-C:C'C:C-C CH 



H\l II II I 



C C C CHz 



/ \ / \ / \ / 



C CHj HjC C 



Hz Hz 



HO 



Rubixanthin 



In addition to the roses listed above, Rosa rugosa has also been found to 

 contain rubixanthin, according to Willstaedt.'^^ It has been found in the 

 treasure-flower gazania {Gazania rigens),^^'^'^^'^ in pot-marigold (Calendula 

 officinalis) ,^^^ in the dodders {Cuscuta suhinclusa and C. salina),^^^ and in 

 the yellow cloudberry (Rubus chamaemorus) .'^'^'^ 



{If) Lutein (Xanthophyll) 



Lutein has long been known to be an invariable constituent of green 

 leaves. As early as 1837, Berzelius^'^ coined the term "xanthophyll" for 

 the yellow pigment appearing in the leaves in the fall foliage. It was first 

 prepared by Willstatter and Mieg^^^ in 1907. Shortly thereafter Willstat- 

 ter and Escher^^ isolated a beautifully crystalline carotenoid from the yolk 

 of hen's egg, which they named lutein, and which possessed properties strik- 

 ingly similar to those of leaf xanthophyll. The two products had a 

 similar empirical composition, C40H56O2; other properties also closely 

 corresponded, with the exception of the melting point, which was higher in 

 the case of the egg-yolk lutein, and the optical rotation, which was lower in 

 the egg-yolk preparation.^*^ By the application of chromatography, Kuhn, 

 Winterstein, and Lederer^^^ were able to demonstrate that the egg-yolk 

 lutein consisted of two fractions. The first of these, which comprised 

 about two-thirds of the total pigment, was identical with the leaf xantho- 

 phyll of Willstatter and Mieg, while the second fraction was apparently 

 similar to a closely related isomer — zeaxanthin. Considerable confusion 

 has since existed in the literature as regards terminology. ^^^ Although the 

 Karrer school has preferred to employ the term xanthophyll or leaf xantho- 

 phyll 104,275 fQj. ^ijg single carotenol, Kuhn considered that the xanthophylls 



2^* H. Willstaedt, Skand. Arch. Physiol, 75, 155-165 (1936). Cited by P. Karrer and 

 I>. Jucker, Carotinoide, Birkhauser, Basle, 1948, p. 174. 



-" R. Willstatter and W. Mieg, Ann., 355, 1-28 (1907); cj. also Berzelius, Ann., 21, 

 257-262, 263-267(1837). 



2"* R. Kuhn, \. Winterstein, and E. Lederer, Z. physiol. Cheni., 197, 141-160 (1931). 



-^* P. Karrer and H. Wehrli, Nova Acta Leopoldina {Halle-am-Saale), 1, 175-275 

 (1933). 



