BODANSKY: CHOLIN ESTERASE 



529 



Table 3 



Concentrations op Cholinesterase Inhibitors Giving 50 Per Cent of 



Uninhibited Velocity 



esterase. The basic dyes, methylene blue, acriflavine, phenothiazone, 

 and thionin, are somewhat less potent inhibitors than physostigmine. 

 Next, in order of potency of inhibition, are thiamin and the antipyrines. 

 Table 4 shows that several antipyrines at a concentration of 3 X 10-^ M 

 inhibit human serum cholinesterase from 30 to 80 per cent. Sulfon- 

 amides at this concentration inhibit only slightly. Acid dyes {e.g., 

 Congo red) and p-phenylenediamine have been reported to have no 

 inhibiting action at 2 X 10"* M.-' 



Table 4 



Inhibition of Human Serum Cholinesterase Activity by Antipyrines and 



Sulfonamides 

 (Zeller) 



