BOD AN SKY: CHOLINESTERASE 



531 



CH= 

 0=C 



=C.CH3 

 N.CH3 

 N— CeHs 



O 



H 



/ 



C2H5 



C-N-CH2-CH2-N 

 -0C4HC, 



vv 



N 



antipyrine 

 CH3-N C=0 



percame 



CHs 



CH 



H2N 



-<^ \-SO2-NH2 



caffeine 



sulfanilamide 



It must be noted, however, that the relationship between the degree 

 of inhibition and the chemical structure of the inhibitors also depends 

 upon the source of the cholinesterase. Table 5 shows that percaine, 



Table 5 



Effect of Drugs on Inhibition of Various Cholinesterases 

 (Zeller and Bissegger") 



irgamid, and isopropyl antipyrine inhibit human serum cholinesterase 

 much more markedly than human red cell or human brain cholin- 

 esterase. In contrast, morphine inhibits these three cholinesterases to 

 about the same extent, and caffeine inhibits human serum cholinesterase 

 only slightly, as compared with its effect on human red cell and human 

 brain cholinesterase. Nachmansohn and Schneeman^" have observed 

 that caffeine inhibits nervous tissue cholinesterases much more mark- 

 edly than those of horse serum and guinea pig pancreas. In contrast, 

 the inhibitions of these latter cholinesterases by quinine, quinidine, 

 cocaine, and lobeline are more marked than those of nervous tissue. 



In addition to the inhibitors which we have discussed above, a num- 

 ber of other substances have been reported to possess an inhibiting ac- 



