398 IV. WAXES, HIGHER ALCOHOLS, ETC. 



500 and 600. It turned out to be an isomer of lutein (xanthophyll) which 

 had an empirical composition of C40H56O2. In spite of the great variation in 

 properties from those of physalien, it had an almost identical spectrum. It 

 was shown to be identical with zeaxanthin, which had been previously 

 isolated by Karrer, Salomon, and Wehrli.^'^ A further study of the pure 

 lycium-physalien preparation showed that, when the pigment was dis- 

 solved in ether and saponified in the cold by standing for 48 hours with 

 methyl-alcoholic potash, two components could be isolated from the reac- 

 tion mixture. The first consisted of a pigment identical with zeaxanthin, 

 while the second product was a saturated fatty acid melting at 62 °C. 

 The latter proved to be palmitic acid. From the relative amounts of 

 zeaxanthin, it was believed that there were two moles of palmitic acid to one 

 of the carotenol. This was strong evidence that lycium and physalien were 

 actually dipalmitates of zeaxanthin. The empirical formula for this 

 ester is C72H116O4, and it breaks down on hydrolysis; 



C,sH5,C0-0C4c^540 0C-C,5H3, — ^-*2CoH3,C00H + C4oHs602 



Zeaxanthin Palmitic Zeax- 



palmitate acid anthin 



That the combination of zeaxanthin with palmitic acid is an ester linkage 

 rather than an ether linkage, as first assumed for the oxygen-containing 

 carotenoids, seems certain in view of the proof furnished by Karrer et al.^'^^ 

 that the oxygen was present in hydroxyl groups. Further experimental 

 confirmation ''^ of the nature of the zeaxanthin combination was afforded by 

 the separation and purification of perhydrophysalien, which was prepared 

 by treating physalein with perbenzoic acid. This compound was a color- 

 less wax which, on hydrolysis, gave rise to exactly two moles of palmitic 

 acid to one of perhydrozeaxanthin. These data are explicable only on the 

 assumption that physalien and lycium are actually dipalmitic acid esters of 

 zeaxanthin. 



A further demonstration of the varied nature of the natural carotenoid 

 esters is evident from the later studies of Zechmeister and Cholnoky*-' on 

 capsanthin. This pigment is the red compound present in the skin of the 

 ripe paprika; these investigators had on all previous attempts over a 

 period of 5 years failed to obtain it in definite crystalline form. However, 

 the crude pigment was obtained in small, red, needle-like crystals, from an 

 acetone solution. A cool alkaline methyl alcohol saponification of this 

 purified product gave rise to a pigment and fatty acids. These results were 

 taken to indicate that capsanthin was present as an ester. However, it 



^19 P. Karrer, II. Salomon, and H. Wehrli, Helv. Chlm. Ada, 12, 790-792 (1929). 

 «" P. Karrer, A. Helfenstein, and H. Wehrli, Helv. Chim. Acta, 13, 87-88 (1930). 

 «i L. Zechmeister and L. v. Cholnoky, Ann., 487, 197-213 (1931). 



