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Phase II Reactions: Glucuronidation

Phase II Reactions: Glucuronidation

Glucuronidation, a pivotal phase II biotransformation process, involves the coupling of glucuronic acid to a drug or xenobiotic. Given its widespread occurrence and critical role in drug metabolism, it's considered the most crucial phase II reaction. It enhances the water solubility of substances, aiding their expulsion from the body. The driving force behind these reactions is a group of enzymes known as UDP-glucuronosyltransferases (UGTs). UGTs facilitate the transfer of a glucuronic acid...

Drug Metabolism: Phase II Reactions

Drug Metabolism: Phase II Reactions

Phase II reactions are essential for the detoxification and elimination of drugs from the body. These reactions involve the conjugation of parent drugs or their phase I metabolites with endogenous molecules, resulting in more hydrophilic drug conjugates. The primary conjugation reactions in this phase are sulfation and glucuronidation. Both sulfation and glucuronidation typically produce biologically inactive metabolites. However, in some cases involving prodrugs, active metabolites may be...

Phase II Reactions: Glutathione Conjugation and Mercapturic Acid Formation

Phase II Reactions: Glutathione Conjugation and Mercapturic Acid Formation

Glutathione, a tripeptide made up of glutamate, cysteine, and glycine, is a critical player in the detoxification of drugs and xenobiotics via a process known as glutathione conjugation or mercapturic acid formation. This phase II biotransformation reaction involves the covalent binding of glutathione to a drug or its metabolite, enhancing the compound's water solubility and enabling its excretion.
Several distinctive characteristics distinguish glutathione conjugation from other phase II...

Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase

Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase

Phase II biotransformation reactions are essential for detoxifying and eliminating xenobiotics, including many pharmaceutical compounds. These reactions typically involve conjugation, the covalent attachment of polar endogenous groups such as glucuronic acid, sulfate, methyl, or acetyl moieties to functional groups introduced during Phase I metabolism. The resulting conjugates are more water-soluble, enabling efficient renal or biliary excretion.The major classes of Phase II enzymes include...

Phase II Reactions: Sulfation and Conjugation with α-Amino Acids

Phase II Reactions: Sulfation and Conjugation with α-Amino Acids

Sulfation and α-amino acid conjugation are two critical biotransformation reactions in drug metabolism. Sulfation, a phase II biotransformation reaction, involves adding a polar sulfate group to a drug, enhancing its water solubility and promoting excretion. This process can either co-occur with or occur independently of glucuronidation. Nonmicrosomal sulfotransferase enzymes catalyze the process. The reaction involves 3'-phosphoadenosine-5'-phosphosulfate or PAPS coenzyme activation, sulfur...

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

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...

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Collection of Alfalfa Root Exudates to Study the Impact of Di(2-ethylhexyl) Phthalate on Metabolite Production

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Autism and phthalate metabolite glucuronidation.

T Peter Stein¹, Margaret D Schluter, Robert A Steer

¹Department of Surgery, School of Osteopathic Medicine, University of Medicine and Dentistry of New Jersey, 2 Medical Center Drive, Stratford, NJ, 08084, USA, tpstein@umdnj.edu.

Journal of Autism and Developmental Disorders

|April 12, 2013

Summary

Environmental chemical exposure may trigger autism spectrum disorders (ASD) in susceptible children. This study found impaired glucuronidation, a key detoxification pathway, in children with ASD, suggesting a potential biological difference.

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Area of Science:

Environmental health
Biochemistry
Neurodevelopmental disorders

Background:

Genetic susceptibility plays a role in autism spectrum disorders (ASD).
The glucuronidation pathway is crucial for metabolizing environmental chemicals.
Variations in glucuronidation efficiency can affect chemical toxicity.

Purpose of the Study:

To investigate the efficiency of the glucuronidation pathway in children with ASD.
To determine if impaired glucuronidation is associated with ASD.

Main Methods:

Collected spot urine samples from children with and without ASD.
Measured glucuronidation efficiency for diethylhexyl phthalate metabolites.
Utilized isotope dilution-liquid chromatography mass spectrometry-mass spectrometry for precise analysis.

Main Results:

Children with ASD exhibited a lower degree of glucuronidation.
The efficiency of this metabolic pathway was compromised in the ASD group.
Specific metabolite analysis revealed differences in conjugation.

Conclusions:

The glucuronidation pathway may function differently in some children with ASD.
This finding suggests a potential biological mechanism linking environmental chemical exposure and ASD.
Further research is warranted to explore therapeutic interventions targeting metabolic pathways.