CEREBROSIDES 473 



it would appear to be a phosphatidic acid formed by the removal of the 

 nitrogenous base, since Feulgen and Bersin" showed that it contained glyc- 

 erophosphate and a fatty aldehyde in equivalent amounts. 



B. CEREBROSIDES 

 1. Introduction 



The cerebrosides consist of that group of conjugate lipids which contains 

 a nitrogenous base, sphingosine, one of several fatty acids of the C24 series, 

 and a molecule of carbohydrate, which may be either galactose or glucose. 

 They are distinguished from lecithin, phosphatidylethanolamine, and 

 phosphatidylserine by the fact that they contain neither glycerol nor phos- 

 phoric acid, while they differ from inositol phosphatides and sphingomyelin 

 in having no phosphoric acid. They are also unique in that they are the 

 only common lipids in which carbohydrate is an essential part of the mole- 

 cule. Since they are usually associated in nature with the various phos- 

 phatides, and since their solubilities in many solvents are similar to those 

 of these substances, the preparation of pure cerebrosides presents some 

 difficulties. 



The cerebrosides were first isolated from the brain by Thudichum,^ who 

 proposed this name for them because of their preparation from the cere- 

 brum. This pioneer worker also demonstrated the presence of two types of 

 cerebrosides, which he called phrenosine and kerasine.^*^ It was not until 

 many years later that such other representatives as nervone^^* and oxyner- 

 yQjjg389 were first recognized. The fact that there are two general groups 

 of cerebrosides, one of which contains galactose and the second of which has 

 the glucose molecule as the component part, has only recently been con- 

 clusively demonstrated.^^" 



Although the cerebrosides are found in the highest concentration in the 

 white matter of the nervous tissues, ^^^ they also occur in the gray matter. 

 In addition to being present in the brain of man and of other mammals, 

 they have been found in the brain of birds. ^^^ They occur in only ex- 

 tremely small amounts, or are entirely absent, in the brain tissue of such 

 lower forms as codfish and shellfish.''^- However, cerebrosides have been 

 isolated from sturgeon brain (Acipenser siurio).^^^ 



^ The original German spelling "kerasin" has been subsequently modified to "cera- 

 sine" to be more in line with current American practice. 



3*8 E. Klenk and R. Harle, Z. physiol. Chem., 189, 243-253 (1930). 



3«9 E. Klenk, Z. -physiol. Chem., 157, 291-298 (1926). 



39» N. Halliday, H. J. Deuel, Jr., L. J. Tragerman. and W. E. Ward. J. Biol. Chem., 

 132, 171-180 (1940). 



3"^ A. Noll, Z. physiol. Chem., 27, 370-397 (1899). 



3»2 A. Argiris, Z. physiol. Chem., 57, 288-295 (1908). 



'" A. Kossel and F. Freytag, Z. physiol. Chem., 17, 431-456 (1893). 



