Related Experiment Video

Updated: Aug 9, 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

Structure-Activity Relationships for CYP4B1 Bioactivation of 4-Ipomeanol Congeners: Direct Correlation between

John P Kowalski1, Matthew G McDonald1, Dale Whittington1

  • 1Department of Medicinal Chemistry, School of Pharmacy , University of Washington , Seattle , Washington 98105 , United States.

Chemical Research in Toxicology
|December 5, 2019
PubMed

Insights

Researchers explored new substrates for Cytochrome P450 4B1 (CYP4B1) to enhance suicide gene therapy. They found N-alkyl-3-furancarboxamides with 3-6 carbon chains are effective, showing a parabolic relationship between chain length and toxicity.

Area of Science:

  • Biochemistry
  • Enzyme kinetics
  • Drug discovery

Background:

  • Cytochrome P450 4B1 (CYP4B1) activates prodrugs for cancer therapy.
  • 4-ipomeanol (IPO) is a CYP4B1-activated cytotoxic agent with metabolic limitations.
  • New pro-toxicant substrates are needed for CYP4B1-based suicide gene systems.

Purpose of the Study:

  • To synthesize and evaluate N-alkyl-3-furancarboxamides as novel CYP4B1 substrates.
  • To establish structure-activity relationships for CYP4B1-mediated cytotoxicity.
  • To investigate the mechanism of CYP4B1 bioactivation and reactive intermediate formation.

Main Methods:

  • Synthesis of N-alkyl-3-furancarboxamides with varying alkyl chain lengths (C1-C8).
  • Cytotoxicity assays in HepG2 cells expressing CYP4B1.
  • In vitro bioactivation studies using purified recombinant rabbit CYP4B1 and nucleophile trapping assays.

Main Results:

  • N-alkyl-3-furancarboxamides with C3-C6 chain lengths exhibited potent cytotoxicity, comparable to IPO.
  • Cytotoxicity and reactive intermediate formation showed a parabolic relationship with alkyl chain length.
  • Time-dependent inhibition studies indicated reactive intermediates can escape the CYP4B1 active site.

Conclusions:

  • N-alkyl-3-furancarboxamides represent a promising class of CYP4B1 substrates.
  • Alkyl chain length critically influences CYP4B1 substrate affinity and bioactivation pathways.
  • The insulated active site of CYP4B1 may contribute to the direct correlation between adduct formation and cytotoxicity.

More Related Videos

Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling09:33

Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling

Published on: March 20, 2018

Functionalized Spirocyclic Heterocycle Synthesis and Cytotoxicity Assay05:17

Functionalized Spirocyclic Heterocycle Synthesis and Cytotoxicity Assay

Published on: February 9, 2021

Related Concept Videos

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH301:11

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
Cycloaddition Reactions: MO Requirements for Photochemical Activation01:12

Cycloaddition Reactions: MO Requirements for Photochemical Activation

Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
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,...
Indirect-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship01:29

Indirect-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship

Indirect-acting cholinergic agonists are agents that interact with the acetylcholinesterase enzyme in the synaptic cleft, preventing the breakdown of acetylcholine into choline and acetate. Consequently, the concentration of acetylcholine in the synaptic cleft increases. These agonists can be classified into reversible and irreversible inhibitors based on their duration of action.
Reversible inhibitors display short to medium durations of action. Short-acting agents include simple alcohols with...
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...