xenobiotic catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of a xenobiotic compound, a compound foreign to the organim exposed to it. It may be synthesized by another organism (like ampicilin) or it can be a synthetic chemical. [GOC:jl, GOC:krc]

Xenobiotic catabolic processes encompass the metabolic breakdown of foreign compounds, collectively known as xenobiotics, which are not naturally found within the body. These processes are crucial for detoxification and elimination of harmful substances, thereby protecting the organism from their detrimental effects. Xenobiotics, including drugs, pollutants, pesticides, and food additives, can enter the body through various routes like ingestion, inhalation, or dermal absorption.

The primary goal of xenobiotic catabolism is to transform these foreign compounds into more water-soluble and excretable forms. This transformation often involves two phases:

**Phase I: Functionalization**
In this phase, xenobiotics undergo structural modifications, typically by introducing polar functional groups like hydroxyl (-OH), carboxyl (-COOH), or amine (-NH2) groups. This step increases their water solubility and facilitates their interaction with enzymes in the subsequent phase. Important enzymes involved in phase I reactions include cytochrome P450 (CYP) enzymes, which catalyze oxidation, reduction, and hydrolysis reactions.

**Phase II: Conjugation**
Phase II reactions involve the conjugation of xenobiotics or their phase I metabolites with endogenous molecules, such as glucuronic acid, sulfate, glutathione, or glycine. This conjugation process further enhances their water solubility and facilitates their excretion. These reactions are typically catalyzed by transferase enzymes, which transfer the conjugating group from a donor molecule to the xenobiotic.

**Excretion**
Once metabolized, the water-soluble xenobiotic metabolites are readily excreted from the body through various routes, including urine, bile, feces, and expired air.

The efficiency of xenobiotic catabolic processes is crucial for maintaining homeostasis and preventing the accumulation of toxic substances in the body. However, it is important to note that these processes can also lead to the formation of reactive intermediates that may cause cellular damage.

Moreover, variations in xenobiotic metabolism among individuals can contribute to differences in drug efficacy and adverse drug reactions. Genetic polymorphisms in metabolic enzymes, such as CYP enzymes, can influence the rate and extent of drug metabolism, leading to variations in drug response.'
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Proteins (16)

Compounds (1,143)