The effect of N-alkyl groups of substituted phenyl-N-alkyl carbamates on the inhibition of human plasma cholinesterase.

The inhibition constants for human plasma cholinesterase (dissociation, carbamylation, decarbamylation, overall bimolecular rate constants) were determined for two series of substituted phenyl-N-alkyl carbamates. N-propyl carbamates were found to be better inhibitors than the corresponding compounds carrying smaller N-alkyl groups. In both series the carbamylation constants of N-ethyl carbamates were lower than those of the N-methyl and N-propyl analogues, whereas the decarbamylation constants of the former were found to be higher than those of the latter carbamates. The experimental results obtained with human plasma cholinesterase are compared with published inhibition constants determined for several types of acetylcholinesterases.