Where are xenobiotics metabolism?

Where are xenobiotics metabolism?

Most of these compounds are subject to metabolism, mainly in the liver. While the metabolism of xenobiotics is generally considered to be a process of detoxification, sometimes the metabolites of compounds that are themselves inert or harmless are biologically active.

Which cell is involved in xenobiotic metabolism?

The ER contains the majority of cytochrome P450 enzymes involved in xenobiotic metabolism, as well as a number of conjugating enzymes. In addition to its role in drug bioactivation and detoxification, the ER can be a target for damage by reactive intermediates leading to cell death or immune-mediated toxicity.

What are the factors influencing xenobiotic metabolism?

Environmental influences include diet, stress, medication, lifestyle, and disease. Genetic variation includes gender, epigenetics, and polymorphisms in genes encoding xenobiotic-metabolizing components such as Phase I and II enzymes, transporters, receptors, and ion channels.

What are xenobiotic metabolizing enzymes?

Xenobiotic metabolizing enzymes, important for the metabolism, elimination and detoxification of exogenous agents, are found in most tissues and organs and are distinguished into phase I and phase II enzymes, as well as phase III transporters.

What is a xenobiotic compound?

Definition. A xenobiotic (Greek, xenos “foreign”; bios “life”) is a compound that is foreign to a living organism. Principal xenobiotics include: drugs, carcinogens and various compounds that have been introduced into the environment by artificial means.

Where does Phase 1 xenobiotic metabolism occur?

Phase I biotransformation reactions introduce or expose functional groups on the drug with the goal of increasing the polarity of the compound. Although Phase I drug metabolism occurs in most tissues, the primary and first pass site of metabolism occurs during hepatic circulation.

How does the liver conduct xenobiotic metabolism?

Hepatic enzymes are responsible for the metabolism of xenobiotics by first activating them (oxidation, reduction, hydrolysis, and/or hydration of the xenobiotic), and then conjugating the active secondary metabolite with glucuronic acid, sulfuric acid, or glutathione, followed by excretion in bile or urine.

What is Bioactivation of xenobiotic compounds?

Bioactivation of a number of xenobiotics, including carbon tetrachloride and acetaminophen, leads to both lipid peroxidation and covalent binding, leaving the scientist unsure about which pathway is fatal. Experiments to test whether acetaminophen toxicity is due solely to one path or the other are inconclusive.

Are xenobiotics nutrients?

For the purpose of this symposium, however, xenobiotic does not include non-essential nutrients which occur in the diet, but will be restricted to environmental compounds which are acutely toxic, potentially toxic requiring activation, or which exhibit long term effects, such as mutagens, carcinogens or teratogens.

How are xenobiotics metabolized and detoxified?

In the first step of xenobiotic metabolisms, foreign compounds are processed by phase I detoxification enzymes. In the phase I reaction, multiple cytochrome P450 enzymes are employed,2 and xenobiotics are modified mainly by oxidation reactions to increase electrophilicity.

What would happen to a xenobiotic without metabolism?

Without metabolism, many xenobiotics would reach toxic concentrations. Most metabolic activity inside the cell requires energy, cofactors, and enzymes in order to occur. Xenobiotic-metabolizing enzymes can be divided into phase I, phase II, and transporter enzymes.

What enzymes are involved in xenobiotic metabolism?

Xenobiotic-metabolizing enzymes can be divided into phase I, phase II, and transporter enzymes. Lipophilic xenobiotics are often first metabolized by phase I enzymes, which function to make xenobiotics more polar and provide sites for conjugation reactions.

What is a xenobiotic concentration?

Some researchers also use the term ‘ xenobiotic concentration ’, meaning a concentration that is not found in nature – so we may have a natural compound present at a xenobiotic concentration. Such a concentration might occur as the result of, for example, an oil spill or discharge of an industrial effluent.

Do xenobiotics in plant foods have antioxidant effects?

Many of the xenobiotics in plant foods have potentially beneficial effects (eg, acting as antioxidants, Chapter 45 ), and knowledge of their metabolism will permit extrapolation from in vitro measurement of antioxidant activity to in vivo protective action.