Xenobiotic metabolism of p‐nitrophenol derivatives by the rice field crayfish (procambarus clarkii)

Abstract

AbstractThe extent and routes of metabolism affect the bioconcentration and toxicity of xenobiotics in crayfish. To investigate the in vivo xenobiotic metabolism of three p‐nitrophenol derivatives, rice field crayfish were exposed to 0.1 to 0.01 mg L−1 14C‐substrate solutions for 15 h. At apparent steady‐state uptake, the crayfish were transferred to a recycling flow‐through metabolism chamber for 24 h where the depurated products were collected and concentrated on a column of Amberlite XAD‐4 resin. The tissue absorption and distribution of 14C‐compounds at the apparent steady‐state and post depuration periods were measured by complete tissue combustion and recovery of evolved 14CO2. The structure and concentration of metabolites in resin and soft tissue extracts were determined by cochromatography with authentic standards in HPLC and TLC systems. The crayfish rapidly absorbed the radiolabeled chemicals from solution and depurated metabolites of oxidation and conjugation reactions. The most prominent metabolites were the β‐D‐glucosides of the free phenols, with lesser amounts of the corresponding sulfate esters. Observed oxidations included O‐demethylation, aromatic sidechain oxidation and phosphorothioate deesterification. Body burdens of the original p‐nitrophenol derivatives were markedly reduced by the presence of these metabolic transformations.