Abstract
Inhibitory effect of organophosphorus pesticides on the activity of carboxylesterase (CE), arylarnidase (AAA) and cholinesterase (ChE) in human plasma was investigated. The CE, AAA and ChE activities in human plasma were inhibited by various organophosphorus pesticides. Especially EDDP, BRP, DEP and DDVP showed low I50 values for these enzymes. Generally, the I50 values of CE were lower than those of AAA and ChE for pesticides. The CE activities of DDVP sprayers were significantly reduced after spraying. The mixed pesticides of MEP and IBP increased the inhibitory effect on the CE activity as compared with the individual of the respective pesticides. All of the pesticides investigated in this study showed noncompetitive inhibition to the CE activity in human plasma. The CE and AAA activties were possibly inhibited by -NO2 radical of MEP stronger than-SCH3 radical of MPP. The pl50 (-log I50) values of various pesticides on these three enzymes were closely related to each other. The correlation coefficient was over than 0.9.
