ENZYMES CONCERNED WITH DIGESTION OF LIPIDS 35 



Table 3 

 Classification of the Inhibitors of Cholinesterases" 



Group Components of group 



Quaternary and ter- Eserine (physostigmine), miotine, urethane, prostigmine, cho- 

 tiary ammonium line, arsenocholine, acetyl-/3-methylcholine, ethoxycholine, 



bases butoxyformocholine, carbaminoylcholine (carbachol, U.S.P.); 



methylene blue, safranine, Nile blue; eseroline, eserine methyl- 

 iodide, etc.; bufotenine; muscarine; curare; endoiodine 6 ; es- 

 modil (N-trimethyl-2-methoxy-2,3-propenylammonium bro- 

 mide). 



Amines and amides Ergotamine, ergobasine; cocaine, novocaine, and other local 

 anesthetics; benzyl alcohol, saligenin c ; morphine, apo- 

 morphine, and other emetics; atropine; strychnine; veratrine; 

 hordenine; strophanthin ; pilocarpine; p-aminobenzoic acid, 

 sulfanilamide; sympathol; racedrine (c^-ephedrine); pervi- 

 tine; veritol (paredrine); hexeton, 5 cardiazol (metrazol), 

 coramine (nikethamide); thiamine; nicotinic acid; urea, his- 

 tamine, d thyroxine. d 



Thiol reagents Iodoacetic acid; maleicacid; alloxan; glutathione; copper. 



Anions Fluoride; oxalate; citrate; arsenite; pyrophosphate; atoxyl; po- 



tassium cyanide. 



Miscellaneous Bile acids; diphtheria and tetanus toxins; vitamin C; methyl 



alcohol, ethyl alcohol; chloral hydrate; ether; chloroform; caf- 

 feine; paraldehyde; phenol; sodium chloride. 



° Data from R. Ammon, Ergeb. Enzymforsch., 9, 35-69 (1943). 

 6 (CH s )»NCH 2 CHOHCH 2 N(CH,),. ' 

 I I 



I I 



e From a chemical standpoint, these do not belong in this group; however, Ammon 

 classifies them here on a pharmacological basis. 



d It is questionable whether these should be included, since their action is principally 

 on the central nervous system. 



The inhibition of cholinesterases is brought about by several substances 

 of physiological importance. Thus, it has been shown that vitamin Bi 

 (thiamine) 213,214 and nicotinic acid 166 have an inhibitory effect, but that such 

 a high concentration is required to produce inhibition that these substances 

 are of no importance from a physiological standpoint. On the other hand, 

 Sadhu 216 has shown that thiamine can counteract the fatiguing action of 

 acetylcholine. It is suggested that thiamine competes with choline for the 

 acetyl radicle resulting in the formation of acetylthiamine and choline. 

 Sobotka and Antopol 216 first called attention to the antagonistic effect of a 



213 D. Glick and W. Antopol, J. Pharmacol. Exptl Therap., 65, 389-394 (1939). 



214 R. Amnion, unpublished work cited bv R. Amnion, Ergeb. Enzymforsch., 9, 35-69 

 (1943). 



215 D. P. Sadhu, Am. J. Physiol, 147, 233-236 (1946). 



216 H. Sobotka and W. Antopol, Enzymologia, 4, 189-191 (1937). 



