COLORED FATS 397 



meister/^'^ three classes of fats are possible, one of which is colorless while 

 two are colored. These are as follows : 



1. Colorless alcohols esterified with (iolorless acids. Examples: Usual fats, waxes, 

 lecithin, and sterol esters; colorless. 



2. Colored acids combhied with colorless alcohols, such as phj-tol (C2oH;i90H). Ex- 

 ample: Chlorophyll; colored. 



3. Colorless acids combined with colored alcohols, such as xanthophyll. Example: 

 Colored waxes; colored. 



The group which is of primary interest to us at present is group 3, since 

 these esters are made up of the usual fatty acids combined with higher di- 

 hydric alcohols. Because such alcohols are insoluble in water and because 

 they are found in the non-saponifiable extract after hydrolysis of the 

 colored fats, it is evident that they are analogous to the waxes. However, 

 instead of having only one hydroxyl group, as is true with the higher alco- 

 hols in most waxes, the colored fats appear to be esters of dihydric carote- 

 noid alcohols. 



A most interesting question arises as to whether the lipochromes are 

 lipids in which the pigments are mechanically mixed or whether an actual 

 combination obtains between the chromogenic material and some compo- 

 nent of the lipid. According to Zechmeister,^'"' Krukenberg advanced the 

 idea in 1882 that the fats and the pigments are merely "associated," al- 

 though he did not furnish any clear-cut evidence to support his hypothesis. 

 One might readily accept the fact that the hydrocarbons, a-, /3-, and 7- 

 carotene, as well as lycopene, would be present as mixtures in fats, since 

 there are no groups available for combination with fatty acids. 



However, Zechmeister and Cholnoky^^'^ were the first to point out that 

 some carotenoid pigments are chemically bound to fatty acids. They ob- 

 tained an almost quantitative separation of the pigment for the coral-red 

 berries of the boxthorn, or matrimony vine (Lycium halimijolium, Sola- 

 naceae), in beautiful crystals, by simple extraction of the berries. The 

 molecular weight of the crystalline material was between 900 and 1000. 

 This was higher than any value previously obtained for carotenoids except 

 one called physalien, which had previously been prepared from the winter 

 ground cherries (Physalis alkekengi) and the Chinese lantern plant {Physalis 

 Jrancheii) , by Kuhn and Wiegand. ^ ^** The Lycium pigment was shown to be 

 identical with physalien. However, when the berry extract was saponified 

 in the cold with a potassiimi hydroxide-methyl alcohol mixture, the pigment 

 gradually passed into the methyl alcohol layer, and a quantitative separa- 

 tion of the pigment was again obtained. In this case, however, the crystal- 

 line pigment which was obtained melted at a temperature more than 

 100 °C. higher than did the physalien, and had a molecular weight between 



"1^ L. Zechmeister and L. v. (^holnoky, .1/;/;., .',81, 42-56 (1930). 

 ^18 R. Kuhn and W. Wiegand, Helv. Chim. Ada, 12, 499-50G (1929). 



