LECITHINS. 243 



The various lecithins stand close to each other in regard to constitu- 

 tion. The amount of phosphorus varies between 3.7-3.97 per cent and 

 the amount of nitrogen between 1.7-1.9 per cent. The so-called 

 di-stearyl-lecithin studied by HOPFE-SEYLER and DIACONOW/ which 

 probably has a different structure, has the formula C44HgoNP09. ERLAND- 

 SEN gives the formula C43HsoNPO9 for the lecithin isolated by him from 

 the heart muscles. 



On saponification with alkalies or baryta-water, lecithin yields fatty 

 acids, glycerophosphoric acid, and choline. It is remarkable that in 

 the cleavage of lecithins a smaller amount of nitrogen than corresponds 

 to the choline is obtained. MAC LEAN 2 who has especially investigated 

 this could not re-obtain the total nitrogen in the lecithins as choline but 

 only a part thereof from heart muscle lecithin, 42 per cent, and from egg- 

 yolk lecithin, 65 per cent. He is therefore of the opinion that the choline 

 group is not the only nitrogenous group in the lecithins and that there- 

 fore the generally accepted formula for lecithin is incorrect. TRIER 3 

 has indeed obtained aminoethyl alcohol as a cleavage product from sev- 

 eral phosphatides, which he calls lecithins, but because of the difficulty 

 in preparing phosphatides in a pure condition we are not sure that he was 

 working with pure substances. Lecithin is slowly decomposed by 

 dilute acids. Besides small quantities of glycerophosphoric acid we 

 have large quantities of free phosphoric acid split off. The lecithins 

 are also decomposed by enzymes (lipase) with the splitting off of fatty 

 acids. 



Lecithin is optically active, and as the glycerophosphoric acid which 

 can be split off is also active, WILLSTATTER and LUDECKE 4 claim that the 

 phosphoric acid is not bound on the middle unsymmetric CH group, but 

 rather at the end CEb group of glycerin. 



Lecithin, according to HOPPE-SEYLER, S is found in nearly all animal 

 and vegetable cells thus far studied, and also in nearly all animal fluids. 

 It is especially abundant in the brain; nerves, fish eggs, yolk of the egg, 

 electrical organs of the Torpedo electricus, semen, and pus, and also in 

 the muscles and blood-corpuscles, blood-plasma, lymph, milk, especially 

 woman's milk, and bile. Lecithin is also found in different pathological 

 tissues or liquids. As the presence of lecithin is only indirectly deter- 

 mined by the detection of phosphorus in organic combinations, it must 

 be borne in mind that the above assertions relate chiefly to the occur- 

 rence of phosphatides. 



1 Hoppe-Seyler, Med. chem. Unters., Heft 2 and 3. 



2 Zeitschr. f . physiol. Chem., 59 and Bioch. Centralbl., 9. 

 3 1. c., Zeitschr. f. physiol. Chem., 73, 76 and 80. 



4 Ber. d. d. chem. Gesellsch., 37. 



6 Physiol. Chem. Berlin, 1877-81, p. 57. 



