[Anticholinesterase activity and toxicity of substituted O,O-dialkyl-S-vinyl phosphates and thiovinyl phosphonium salts].

A kinetic investigation of the human erythrocyte and housefly head acetylcholinesterase irreversible inhibition with thiovinyl phosphates is performed and an activation effect of thioalkyl alpha-substituents in the vinyl group is observed. Thiovinyl phosphates in vitro are less selective to the insect enzyme than the corresponding oxygen analogues. Their inhibitory potency rises with lengthening of the alkoxyl radicals at a phosphorus atom but the correlation with the toxicity is absent. Phosphonium salts having a thiovinyl substituent inhibit the enzyme via the reversible mechanism typical for onium compounds.