Comparative metabolism of benfuracarb in in vitro mammalian hepatic microsomes model and its implications for chemical risk assessment

Toxicol Lett. 2014 Jan 13;224(2):290-9. doi: 10.1016/j.toxlet.2013.08.009. Epub 2013 Aug 16.

Abstract

In vitro metabolism of benfuracarb in liver microsomes from seven species was studied in order to quantitate species-specific metabolic profiles and enhance benfuracarb risk assessment by interspecies comparisons. Using LC-MS/MS, a total of seven phase-I-metabolites were detected from the extracted chromatograms and six of them were unequivocally identified. Benfuracarb was metabolized via two metabolic pathways, the sulfur oxidation pathway and nitrogen sulfur bond cleavage, yielding carbofuran, which metabolized further. Analysis of the metabolic profiles showed that benfuracarb was extensively metabolized with roughly similar profiles in different species in vitro. In vitro intrinsic clearance rates as well as calculated in vivo hepatic clearances indicated that all seven species metabolize benfuracarb via the carbofuran metabolic pathway more rapidly than the sulfoxidation pathway. The highest interspecies differences in hepatic clearance rate values were for mouse and rat liver microsomes compared to human, i.e. 4.8 and 4.1-fold higher, as illustrated by in vivo hepatic clearance of carbofuran. Overall, there are quantitative interspecies differences in the metabolic profiles and kinetics of benfuracarb biotransformation. These findings illustrate that in vitro studies of benfuracarb metabolite profiles and toxicokinetics are helpful for the proper selection and interpretation of animal models for toxicological evaluation and chemical risk assessment.

Keywords: In vitro metabolism; P450; Pesticides; Risk assessment; Toxicokinetics.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Benzofurans / metabolism*
  • Benzofurans / toxicity
  • Dogs
  • Female
  • Humans
  • Insecticides / metabolism*
  • Macaca fascicularis
  • Male
  • Mice
  • Mice, Inbred DBA
  • Microsomes, Liver / metabolism*
  • Middle Aged
  • Rabbits
  • Rats
  • Risk Assessment*
  • Species Specificity
  • beta-Alanine / analogs & derivatives*
  • beta-Alanine / metabolism
  • beta-Alanine / toxicity

Substances

  • Benzofurans
  • Insecticides
  • beta-Alanine
  • benfuracarb