5G2 VI. CAROTENOIDS AND RELATED COMPOUNDS 



pigment was identical with xanthopliyll. Karrer et nl. succeeded in 

 separating the pigment in pure form and in characterizing and naming 

 j^ 283,324 The latter workers differentiated zeaxanthin from egg-yolk 

 lutein. The formula for zeaxanthin has been given earlier (see page 555), 

 where the justification for the structure assigned to it was discussed. 



a. Occurrence. Zeaxanthin is largely confined to the plant kingdom, 

 where it occurs in both free and cstcrificd forms. It is present in the free 

 state in yellow corn (Zea mays),^-^ as well as in the seeds of the Euonymus 

 europaeus L. (spindle tree)."^-"' This is also true in the case of rose hips 

 (Rosa canina, R. eglanteria, and R. damascena) ,^^^'^''^* and in the flowers of 

 Senecio doronicum (leopard bane groundsel), ^"^ of Crocus sativus (saffron 

 crocus), '^^ and of Viola tricolor (pansy). ^^'-^ Zeaxanthin has likewise been 

 reported in the coneflower {Rudbeckia speciosa N ewmanni) .^^-^^^ 



Zeaxanthin is found in many fruits such as the Solanum hendersoni 

 (Henderson Jerusalem cherry), ^"^ Lycopersicon escnlentum (tomato), ^^^ 

 Diospyros costata (persimmon), ^^^ Cucurhita pepo L. (pumpkin), ^^^ Citrus 

 aurantium (Seville orange), ^^^ and Prunus persica (peach). '"^ 



The esterified forms of zeaxanthin are found in the calices and berries of 

 the Physalis alkekengi (winter ground-cherry) and P. franchetti (Chinese 

 lantern), 2''^ as well as in Lycium halimifoUum (boxthom berries), ^^^ where it 

 is identified as physalien. It is also esterified in Hippophae rhamnoides 

 (sea buckthorn), ^"^ and in the pimiento or Japanese red pepper {Capsicum 

 frutescens japonicum) .^"^^ Karrer ct al."^ have likewise reported the esteri- 

 fied form of zeaxanthin in the berry of the red kaki or Japanese persimmon 

 {Diospyros kaki). 



It is not known whether the zeaxanthin present in the liver of the green 

 edible water-frog {Rana escuJenta)^^^ is in the free form or appears as an 

 ester. Chargaff ^^'^ has noted the presence of this carotenol in several types 

 of microorganisms, i.e., the cocci, Sarcina aurantiaca and Staphylococcus 

 pyogenes aureus. Karrer and his co-workers^^^ found zeaxanthin as a 

 constituent of the brown marine alga, Halyseris {Dictyopteris) polypod- 

 ioides. 



The presence of zeaxanthin in animal products must be regarded as ad- 

 ventitious, since it must originate in the ingested carotenol, at least as far as 

 the higher animals are concerned. It has been demonstrated to be a com- 

 ponent of human fat^^ and human liver. ^^^ It has been proved to be a 

 component of the yolk of hen egg."^ Strain^^* as well as Euler and Gard^^^ 



324 p. Karrer, H. Salomon, and H. Wehrli, Helv. Chim. Acta, 12, 790-792 (1929). 



325 J. C. Sadana and B. Ahmad, Indian J. Med. Research, 34, 59-68 (1946); Chem. 

 Abst., 41, 6602 (1947). 



326 L. Zechmeister and L. v. Cholnoky, Ann., 489, 1-6 (1931). 



327 E. Chargaff, Compt. rend., 197, 946-948 (1933). 



328 H. H. Strain, Chromatographic Adsorption Analysis, Interscience, New York, 1942. 



329 H. V. Euler and U. Gard, Arkiv Kemi Mineral. GeoL, BIO, No. 19, 1-6 (1931). 



