The role of hydrolases in insecticide metabolism and the toxicological significance of the metabolites

Abstract

The hydrolytic enzymes involved in insecticide metabolism are the phosphorotriester hydrolases, carboxylesterases, carboxylamidases and epoxide hydrolases The phosphorotriester hydrolases (arylesterases and DFP-ases) catalyze the P-anhydride bond cleavage of the “leaving group”, a major route of detoxication of organophosphates. Carboxylesterases hydrolyze the carboethoxy group of malathion and also have hydrolytic activity toward certain synthetic pyrethroids, Carboxylamidases are involved in the hydrolysis of amide-containing phosphorothionates, N-formyl metabolites and substituted fluoroacetamides. Epoxide hydrolases hydrate certain cyclodiene insecticides and are probably involved in the metabolism of some other insecticides. Overall, the hydrolysis of insecticides increases the polarity of the metabolites and decreases their biological activity.