CHOLINE'AND ALLIED SUBSTANCES 61 



t 



carefully scrutinised. 1 Neurine occurs as a product of putrefaction and 

 was isolated by Brieger [1885, 1, pp. 25-39] from putrid meat (horse, ox, 

 human corpses). Brieger studied the physiological action of neurine in 

 some detail and naturally assumed that the base was formed from 

 choline by bacterial action. This assumption has never been proved 

 rigidly, but the possibility should be taken into account with reference 

 to Kutscher's alleged discovery [1905 ; Ch. V, creatine] of neurine in 

 commercial meat extract Krimberg [1906, I ; Ch. V, methylguan- 

 idine] could not find neurine in an extract of perfectly fresh meat 

 and concludes [1908,2; Ch. Ill, carnitine] that it is not present in 

 muscle. Lohmann [1909] obtained neurine from the supra-renal gland, 

 but here again it is not clear to what extent sterility was ensured. 

 Brieger [1885, I, p. 6l] obtained neurine from fresh human brain 

 by hydrolysis with hydrochloric acid. 



Neurine is most readily obtained synthetically and was first pre- 

 pared by Hofmann [1858] nine years before the synthesis of choline 

 by Wurtz. Hofmann treated the condensation product of trimethyl- 

 amine and ethylene dibromide with moist silver oxide, which removes 

 hydrobromic acid, and forms neurine bromide : 



/Br /Br 



(CH.,), : N/ + AgOH = (CH 3 ) 3 : N/ + AgBr + H a O. 



\CH 2 . CH 2 Br \CH : CH., 



Baeyer [1869] prepared neurine from choline by heating the 

 latter with concentrated hydriodic acid and then treating the resulting 

 iodo-compound with silver oxide as in Hofmann's synthesis. Neurine 

 is perhaps also formed from choline by boiling with concentrated baryta 

 and this may have caused it to accompany choline in Liebreich's 

 hydrolysis of protagon. According to Brieger [1885, i, pp. 33, 34] 

 neurine appears to be formed from choline by long standing in aqueous 

 solution. 



Physiological Action of Choline and of Neurine. 



When given subcutaneously or by the mouth to rabbits in doses of 

 I grm., choline produces no severe symptoms and is not excreted in 

 the urine (von Hoesslin [1906]). Riesser [191 3 ; Ch. V, creatine] 

 found that rabbits often withstood a daily injection of O'5-i grm. 

 choline. Similarly the urine of rabbits, fed on lecithin, does not con- 

 tain choline, but only a little glycero-phosphoric and formic acids 



1 Thus Kutscher and Lohmann's statement [1906, 2, under choline] that neurine occurs 

 in human urine has passed into the literature (" Biochemisches Handlexicon "), although 

 these authors subsequently [1906, 4 ; Ch. V, methylguanidine] stated that their supposed 

 gold salt of neurine was in reality methylpyridyl ammonium aurichloride. 



