Collect. Czech. Chem. Commun. 1997, 62, 521-526

Inhibition of Plasma Cholinesterase by O-Alkylfluorophosphonates

Jiří Cabal, Jiří Kassa and Jiří Patočka

Department of Toxicology, Military Medical Academy, 500 01 Hradec Králové, Czech Republic


Inhibition of plasma cholinesterase by three methylfluorophosphonates (MFF), sarin, soman and cyclosin, and by the products of their hydrolysis and alcoholysis was examined. Inhibition by phosphonic acids and by methyl esters derived from MFF was purely competitive while that by MFF was irreversible. The rate of phosphorylation of cholinesterase by MFF differs, depending on the structure of the alkoxy group in the MFF and decreases in the sequence soman-sarin-cyclosin. The affinity values of MFF, phosphonic acids and methyl esters of phosphonic acid for cholinesterase are comparable. The in vitro kinetic parameters suggest that plasma cholinesterase might act as a natural detoxicating agent in cases of poisoning with the above inhibitors of acetylcholinesterase.

Keywords: Sarin; Soman; Acetylcholinesterase; Inhibitors.