Invitro metabolic kinetics of cresyl diphenyl phosphate (CDP) in liver microsomes of crucian carp (Carassius carassius).

Abstract

Cresyl diphenyl phosphate (CDP), as a kind of aryl substituted organophosphate esters (OPEs), is commonly used as emerging flame retardants and plasticizers detected in environmental media. Due to the accumulation of CDP in organisms, it is very important to discover the toxicological mechanism and metabolic process of CDP. Hence, liver microsomes of crucian carps (Carassius carassius) were prepared for invitro metabolism kinetics assay to estimate metabolism rates of CDP. After 140min incubation, the depletion of CDP accounted for 58.1%-77.1% (expect 0.5 and 2μM) of the administrated concentrations. The depletion rates were best fitted to the Michaelis-Menten model (R2=0.995), where maximum velocity (Vmax) and Michaelis-Menten constant (Km) were 12,700±2120pmolmin-1·mg-1 protein and 1030±212μM, respectively. Moreover, the invitro hepatic clearance (CLint) of CDP was 12.3μLmin-1·mg-1 protein. Log Kow and bioconcentration factor (BCF) of aryl-OPEs were both higher than those of alkyl- and chlorinated-OPEs, indicating that CDP may easily accumulate in aquatic organisms. The results made clear that the metabolism rate of CDP was greater than those of other OPEs detected in liver microsomes in previous research. This paper was first of its kind to comprehensively investigate the invitro metabolic kinetics of CDP in fish liver microsomes. The present study might provide useful information to understand the environmental fate and metabolic processes of these kinds of substances, and also provide a theoretical basis for the ecological risk assessment of emerging contaminants.