In vitro and in vivo acetylcholinesterase-inhibiting effect of new classesof organophosphorus compounds

Anticholinesterase properties of 14 new synthesized organophosphorus (OP) c ompounds and four of their starting substances were tested in vitro and in vivo using electric eel acetylcholinesterase (AChE) and Rana ridibunda (fro g of lowland) tadpoles, respectively. Gusathion-M(R) was used as a referenc e anti-AChE agent. Acetylcholinesterase inhibition capacity of tested compo unds was assayed for 30-min period in vitro studies using electric eel AChE , of which 14 OP compounds inhibited enzyme activity more than 50% within 3 0 min, excluding Gusathion-M. However, four of the compounds inhibited AChE less than 50% during the test period. On the other hand, 12 of the OPs did not bring about mortality, whereas six of the tested compounds were found to be lethal agents for R. ridibunda tadpoles, for which values of concentr ation causing 50% lethality ranged from 14.42 to 89.95 ppm. Also, the highe st degree of enzyme inhibition occurred by diethyl chlorophosphate (ETCP), which inhibited AChE activity 62% at 2.89 ppm in 24-h toxicity tests and wh ich was more effective than Gusathion-M. The lethal OP compounds represente d good correlation between dose and enzyme-inhibition capability in in vivo tests, but only ETCP showed such a relation for anti-AChE effect in both i n vitro and in vivo conditions.