Related Experiment Video

Updated: Jul 14, 2026

Mass Spectrometry and Luminogenic-based Approaches to Characterize Phase I Metabolic Competency of In Vitro Cell Cultures
10:44

Mass Spectrometry and Luminogenic-based Approaches to Characterize Phase I Metabolic Competency of In Vitro Cell Cultures

Published on: March 28, 2017

Metabolism of benzo(a)pyrene by duck liver microsomes

S Honey1, P O'Keefe, A T Drahushuk

  • 1Environmental Toxicology and Chemistry Laboratory, Great Lakes Center for Environmental Research and Education, State University of New York College at Buffalo, 14222, USA.

Comparative Biochemistry and Physiology. Toxicology & Pharmacology : CBP
|October 26, 2000
PubMed

Insights

Duck liver microsomes from polluted areas metabolize benzo(a)pyrene [BP] faster, showing higher cytochrome P-450 1A1 levels. Metabolite patterns differ, with polluted ducks producing more dihydrodiols, indicating environmental impact on toxicant metabolism.

Area of Science:

  • Environmental Toxicology
  • Biochemistry
  • Comparative Metabolism

Background:

  • Benzo(a)pyrene (BP) is a model carcinogenic polycyclic aromatic hydrocarbon (PAH).
  • Hepatic microsomes are key for xenobiotic metabolism in vertebrates.
  • Ducks are valuable bioindicators of environmental contamination.

Purpose of the Study:

  • Investigate benzo(a)pyrene metabolism in mallard and common merganser ducks.
  • Compare BP metabolism rates and metabolite profiles between ducks from contaminated and non-contaminated sites.
  • Assess the role of cytochrome P-450 1A1 in BP metabolism in these species.

Main Methods:

  • Collected liver microsomes from mallard and common merganser ducks from varying pollution levels.
  • Quantified BP metabolism rates using microsomal protein assays.
  • Analyzed BP metabolite profiles using chromatography and mass spectrometry.
  • Measured cytochrome P-450 1A1 levels.

Main Results:

  • Significantly higher BP metabolism rates in ducks from polluted areas compared to non-polluted areas.
  • Elevated cytochrome P-450 1A1 levels in liver microsomes of ducks from polluted sites.
  • Qualitatively similar major BP metabolites, but quantitative differences in metabolite patterns observed.
  • Polluted-area ducks produced more benzo-ring dihydrodiols; non-polluted ducks produced more BP-phenols.
  • Predominant enantiomer of BP-7,8-diol was (-)R,R.

Conclusions:

  • Environmental contamination significantly induces BP metabolism and cytochrome P-450 1A1 in ducks.
  • Duck liver microsomal enzymes exhibit differential regioselectivity in BP metabolism based on environmental exposure.
  • Duck and rat liver microsomal enzymes show similar stereoselectivity but different regioselectivity in BP metabolism.

More Related Videos

Elucidating the Metabolism of 2,4-Dibromophenol in Plants06:54

Elucidating the Metabolism of 2,4-Dibromophenol in Plants

Published on: February 10, 2023

Unveiling Xenobiotic Transport and Effects in Isolated Mitochondria: Insights from Respirometric and Enzymatic Assays08:03

Unveiling Xenobiotic Transport and Effects in Isolated Mitochondria: Insights from Respirometric and Enzymatic Assays

Published on: March 7, 2025

Related Concept Videos

Oxidation of Phenols to Quinones01:17

Oxidation of Phenols to Quinones

In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Drug Metabolism: Phase I Reactions01:17

Drug Metabolism: Phase I Reactions

A phase I reaction is a biochemical process that introduces a functionally reactive polar group to a substance. This transformation predominantly occurs in the liver, facilitated by the cytochrome P450 system of hemoproteins situated in the lipophilic endoplasmic reticulum of cells. The metabolite generated through this process can have varying polarities. If it is sufficiently polar, it can be easily excreted in the urine due to its water compatibility. However, if the metabolite is nonpolar,...
Phase I Oxidative Reactions: Overview01:19

Phase I Oxidative Reactions: Overview

Phase I biotransformation, or functionalization, is a crucial chemical process that converts drugs and other xenobiotics into more water-soluble forms, facilitating expulsion from the body. It involves oxidative, reductive, and hydrolytic reactions that add or unveil polar functional groups on lipophilic substrates. Key players in phase I reactions are the mixed-function oxidases. Situated in liver cell microsomes, these enzymes predominantly carry out drug metabolism. They require molecular...
Phase I Reactions: Oxidation of Aliphatic and Aromatic Carbon-Containing Systems01:19

Phase I Reactions: Oxidation of Aliphatic and Aromatic Carbon-Containing Systems

Phase I biotransformation reactions are integral to drug metabolism, predominantly involving oxidative, reductive, and hydrolytic transformations. Chief among these are oxidative reactions, which enhance the hydrophilicity of xenobiotics and introduce polar functional groups to facilitate their elimination from the body.
Oxidation reactions are fundamental in aromatic carbon-containing systems. An example is the hydroxylation of phenobarbital, a process that transforms it into...
Bioactivation and Tissue Toxicity01:25

Bioactivation and Tissue Toxicity

Bioactivation is a metabolic process that transforms less reactive substances into highly reactive metabolites, initiating tissue toxicity. This transformation can lead to various toxic effects, including carcinogenesis and teratogenesis. Reactive metabolites are classified into two main types: electrophiles and free radicals.Electrophiles are electron-deficient species and are produced primarily by the enzyme cytochrome P-450 during the metabolism of compounds containing carbon, nitrogen, or...
Jaundice01:25

Jaundice

Jaundice, or icterus, is the yellow discoloration of the skin, sclerae, and mucous membranes. It happens when plasma bilirubin levels rise above 2.5-3 mg/dL, leading to bilirubin deposition in tissue.Bilirubin is a byproduct of hemoglobin degradation. In macrophages, hemoglobin breaks down into globin and heme. Globin is converted into amino acids, while heme is turned into biliverdin by heme oxygenase, which is then reduced to unconjugated bilirubin by biliverdin reductase.Unconjugated...