THE LECITHINS 409 



and Pcittrc,-'- wlio were able to separate two calcium salts of glycerophos- 

 I)honc acid from lecithin; these were identified as a- and /3-salts. Bailly" 

 further demonstrated that a cystalline sodium salt of jS-glycerophosphoric 

 acid and an amorphous sodium salt of a-glycerophosphoric acid could be 

 isolated both from egg luid from l)rain lecithin. Finally, Karrer and 

 Salomon''^ pros{nited a method foi' tlio separation of «- and /3-glycerophos- 

 phoric acid; they were able to obtain both compounds from lecithin. 



HgC-O-CR HzC-O-CR 



HC-O-CR' HC-O-P-OCHzCHjNlCHj),' 



H^C-0°-lj>-0CH3CH3N(CH,)3 h C-O^^CR' °" 



OH OH ^ 



a-Lecithiii /3-Lecithin 



Since R and R' in the lecithin formulas represent different fatty acids, 

 it is evident that many possible variations exist in specific lecithins, de- 

 pending upon the particular fatty acids represented and their position in 

 the molecule. If one includes the possibility of /3- as well as of a-lecithins, 

 then the number of opportunities for the various types of lecithin is greatly 

 increased. 



{2) Distribution of the Lecithins and Other Phospholipids 



Although some phospholipids have been reported in such vegetable oils 

 as corn, rapeseed, and so.ybean, the principal source of these compounds is 

 found in animal tissues. The phosphatides are not present as components 

 of the depot fat, but they make up a considerable proportion of the liver 

 and brain lipids, as well as of blood fat. 



Both or- and /3-forms of lecithin and cephalin occur in animal tissue. 

 By the use of a method of fractionation of a- and /3-lecithins based upon the 

 differential solubility of their cadmium salts in hot and cold acetone, 

 Welch^* studied the distribution of the a- and /3-isomers of both lecithin 

 and cephahn in a number of tissues from several species of animals. Al- 

 though the a-form of lecithin is usually present in a considerably larger 

 amount than the /?-form, it is true that the j8-compound is invariably 

 found. The higher levels of the a-form in the liver and heart are in 

 accordance with the results of Yoshinaga,^^ while the predominance of the 

 a-lecithin in the brain has also been reported by Rae." These data are 

 summarized in Table 1. 



32 E. Fourneau and M. Peittre, Bull. soc. chim. [4], 11, 805-810 (1912). 



" O. Bailly, Ann. chim. [9], 6, 96-154 (1916). 



" P. Karrer and H. Salomon, Helv. Chim. Ada, 9, 3-23 (1926). 



^ E. A. Welcfi, /. Biol. Chem., 161, 65-69 (1945). 



56 T. Yoshinaga, J. Biochem. Japan, 27, 81-90 (1938). 



^ J. J. Rae, Biochem. J., 28, 152-156 (1934). 



