ACETAL PHOSPHATIDES (PLASMALOGENS) 471 



staining of the chromatic structures of the nuclei obtains, due to the alde- 

 hyde groups which are set free by the hydrolysis of thymonucleic acid. 



However, Feulgen noted that his reagent stained not only the nuclei but 

 also the cytoplasm of many tissues, although the cytoplasm retained the 

 dye to a lesser extent. When the tissue had been previously defatted, 

 staining was no longer observed in the cytoplasm, although that in the 

 nuclei was unaffected. Feulgen, therefore, suggested that the unknown 

 carriers of the fuchsin-sulfurous acid in the cytoplasm should be designated 

 as plasmal; since the staining was markedly accelerated by a preliminary 

 treatment with acid, this investigator believed that the plasmal was not 

 present in the cell as such but in the form of a precursor which was called 

 plasmaloge7i^^^ 



When attempts were made to isolate plasmalogen, it was found that it 

 was invariably present in the phosphatide fraction. When mercuric 

 chloride was added to phospholipid suspensions from brain, muscle, or 

 heart, a strong reaction indicating the presence of plasmal was immediately 

 obtained. Plasmal was first isolated by Feulgen et al.^^^ from horse muscle 

 phosphatides, by steam distillation, and by subsequent condensation as the 

 semithiocarbazone. A better method for the preparation of plasmal has 

 recently been proposed by Behrens.^^- Employing this method, he was 

 able to prepare 1-1.5 g. of plasmal semithiocarbazone from 10 kg. of horse 

 meat. Anchel and AVaelsch^*^ have developed a method for the isolation of 

 the plasmals from comparatively small amounts of tissue. Klenk^^* found 

 that non-saponifiable material separated from the cephalin fraction of brain 

 responds to the fuchsin test, and has properties identical with those of the 

 acetal phospholipids which were separated in the form of dimethyl acetals. 



Feulgen and Bersin''' succeeded in preparing plasmalogen by virtue of its 

 relative stability against alkali. On treatment of the phosphatide emul- 

 sion from beef muscle with sodium hydroxide, most of the plasmalogen re- 

 mained intact, while the contaminating phosphatides were largely removed 

 by saponification. Plasmalogen, together Avith the fatty acids, can be pre- 

 cipitated at this stage by brucine. After removal of the brucine soaps by 

 extraction with acetone, the plasmalogen is purified by repeated treating 

 with benzene, in which it is insoluble. The plasmalogen is then crystal- 

 lized from alcohol at room temperature. 



(1) Structure of the Plasmalogens 



The plasmalogens are acetals of fatty aldehydes which are combined 

 with colamine glycerophosphate." Two possible types of compounds are 



»i R. Feulgen, K. Imhiiuser, and M. Behrens, Z. physiol. Chetn., 180, 161-179 (1929). 



3«2 M. Behrens, Z. physiol. Chem., 1.91, 183-186 (1930). 



»8' M. Anchel and II. Waelsrh, ./. Biol. Chem., 145, 605-613 (1942). 



3" E. Klenk, Z. physiol. Chem., 281, 25-28 (1944). 



