II. CHEMISTRY 



CH,— CHo— N=(CH3)3 



I u 



OH 



Choline 



CH2— CH2— N=(CH3)3 



I u 



o 



0=C— CH3 



Acetylcholine 



CHo — CH2 — ■N=(CH3)3 



I u 



o 



0=P— 0_ 



I 



OH 



Phosphorylcholine 



O 

 CH.— CHo— CH— C— OH 



NH, 



CH3 



Methionine 



0=C— CH,— N=(CH3)3 



I u 



0- 



Betaine 



0=C— CH,— N=(CH3)3 



I u 



H 



Betaine aldehyde 



O 



II 

 CH,— C— 0_ 



s— + 



II 



(CH3)2 



Dimethylthetin 



O 



II 

 CH,— CH, — C— 0_ 



I 



s— + 



(CH3)2 



Dimethyl-/3-propiothetin 



Surprisingly, the first isolations of choline Avere not from materials rich 

 in the complex lipids but from hog bile by Strecker^ in 1849 and from an 

 alkaloid of Avhite mustard seed (Sinapis alba) by Babo and Hirschbrunn^ 

 in 1852. The latter workers named their product sinkaline, whereas Strecker^ 

 in 1862 applied the name choline to the substance obtained from bile. 

 Subsequently, Liebreich'* separated a fraction from hydrolyzed crude brain 

 lecithin (protagon), which he named neurine. Dybkowsky^ soon found that 

 Liebrich's base was choline and not the vinyl compound known as neurine 

 at the present time, and Claus and Keese^ demonstrated the identity of 

 sinkaline and choline. 



Choline has been obtained from a great variety of tissues and fluids 



1 A. Strecker, Ann. 70, 149 (1849). 



2 L. von Babo and M. Hirschlirunn, Ann. 84, 10 (1852). 



3 A. Strecker, Ann. 123, 353 (1862). 

 ^ O. Liebreich, Ann. 134, 29 (1865). 



5 W. Dybkowsky, ./. prakt. Chem. 100, 153 (1867). 



6 A. Claus and C. Keesd, /. -prakt. Chem. 102, 24 (1867). 



'^tc^^ 



