BIOACTIVATION OF BIS[P-NITROPHENYL]PHOSPHATE BY PHOSPHOESTERASES OF THE EARTHWORM, LUMBRICUS-TERRESTRIS

Abstract

In view of the ability of several phosphoesterases to hydrolyze organophosphates to toxic-phenols,the bioactivation of bis[p-nitrophenyl] phosphate (BNPP) by the earthworm Lumbricus terrestris was investigated. In a contact toxicity test, BNPP was was less toxic than the metabolite p-nitrophenol (PNP), but more toxic than the metabolite p-nitrophenylphosphate (PNPP). Results from an artificial soil test (soil containing BNPP) revealed that the phosphomonoesterase and phosphodiesterase activities from the enteric tissue of the annelid could be selectively depressed without significant reduction of these activities in other tissues. Since these esterase activities are 5 to 7 fold higher in the enteric tissue, these results suggest that the phosphoesterases in the annelid participate in the activation of BNPP to the more toxic metabolite, p-nitrophenol.