What are xenobiotics and their examples?
Xenobiotic is a term used to describe chemical substances that are foreign to animal life and thus includes such examples as plant constituents, drugs, pesticides, cosmetics, flavorings, fragrances, food additives, industrial chemicals and environmental pollutants.
What is xenobiotic compound?
A xenobiotic (Greek, xenos “foreign”; bios “life”) is a compound that is foreign to a living organism. A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism.
What is the study of xenobiotics called?
The studies on xenobiotics include the rates and extents of the processes and the biological consequences. The term Xenobiotic comes from the Greek for xeno (foreign) and biotics (of or pertaining to life). Examples of Xenobiotics are compounds that include drugs, food additives, and environmental pollutants.
Are vitamins xenobiotics?
Xenobiotic Storage Depots Plasma proteins represent a storage site for many xenobiotics (e.g., salicylates, barbiturates, cardiac glycosides) and important physiologic constituents, including steroid hormones, vitamins, and various essential minerals.
Is caffeine a xenobiotic?
Caffeine is one of the most widely used psychoactive drugs in humans, acting as a stimulant, and has been employed as a convenient model xenobiotic in Drosophila research, where it is known to induce the expression of a number of P450 and GST genes in Drosophila S2 cells, larvae and adults [19–22].
What is not a xenobiotic?
Definition. Xenobiotics are chemicals found but not produced in organisms or the environment. Some naturally occurring chemicals (endobiotics) become xenobiotics when present in the environment at excessive concentrations. The “xeno” in “xenobiotics” comes from the Greek word xenos meaning guest, friend, or foreigner.
Why xenobiotics are recalcitrant?
But some xenobiotics are recalcitrant in nature because of various reasons. Some of them cannot be used as substrate by microbes, some cannot transport them due to absence of transporting enzymes and some are in accessible to microbes due to larger structure and insolubility.
Is alcohol a xenobiotic?
Abstract. Alcohol and xenobiotics share the same oxidative microsomal pathway, which is mainly located in the endoplasmic reticulum of hepatocytes.
Does alcohol inhibit CYP450?
Ethanol is known to induce certain cytochrome P450 (CYP) enzymes, particularly the 2E1 isoform, which has been shown to metabolise arachidonic acid (AA) to the 19-hydroxy metabolite (19-HETE), which could have pro-hypertensive activity; CYP4A, by comparison, is the principal AA omega-hydroxylase in the liver.
What is xenobiotic degradation?
In contrast, man-made compounds, also known as xenobiotics, are often refractory to degradation. Some compounds may be transformed only in the presence of another compound which appears as a carbon and energy source. Very often compounds are degraded sequentially through the activity of a series of different organisms.
Are xenobiotics harmful?
With the development of the society, the xenobiotics have brought high potential risk to human and animal. Insecticides bring high risk to human and animal through food, water, and air. …
Why xenobiotics are carcinogenic?
It appears that most of the carcinogen-metabolizing enzymes are inducible by xenobiotics: they respond to environmental stimuli and therefore vary in their activity. Furthermore, many of the encoding genes are polymorphic and multiple allelic variants relevant for the phenotype may exist in human populations.
What are xenobiotics Mcq?
What are xenobiotics? Explanation: All chemical substances that are not nutrients for the body and enter the body through different routes like inhalation, ingestion, absorption, etc.
What is xenobiotics PDF?
Xenobiotic compounds are man made chemicals that are present in the environment at higher concentration. These are either not produced naturally or are produced at much lower amount than that by man. The compounds that resist biodegradation and persist in the environment for long period of time are called recalcitrant.
What is xenobiotic stress?
Description. Xenobiotics such as drugs, chemotherapy, food additives, and environmental pollutants are foreign chemical compounds to our biological system. These compounds generate several free radicals that lead to increase the oxidative stress in the cells.
What are xenobiotics Slideshare?
A xenobiotic is a foreign chemical substance found within an organism that is not normally naturally produced by or expected to be present within. Specifically, drugs such as antibiotics are xenobiotics in humans because the human body does not produce them itself, nor are they part of a normal food.
Which one is the rate limiting step in the oxidation of xenobiotics?
Explanation: The rate-limiting step is the transfer of an electron from NADPH to the complex of substrate and cytochrome 450. The gaining of an electron by cytochrome 450 reduces the Fe3+ to Fe2+. This step is considered the rate-limiting step of the oxidation of xenobiotics.
How are xenobiotics excreted?
Xenobiotics are excreted via faeces, urine, sweat, breath or milk. They are consequently excreted in faeces. Many compounds are excreted via kidneys. Excretion of toxicants in sweat is importance for detecting agents used for doping.
What organ in the body is responsible for drug and xenobiotic metabolism?
The liver is the principal site of drug metabolism; moreover, hepatic metabolic CL is the predominant elimination route for oral marketed drugs. The most important drug metabolism enzyme family is cytochrome P-450, a superfamily of membrane-bound isoenzymes that catalyses the oxidation of many drugs.
What is a Phase 1 reaction?
Phase 1 metabolism involves chemical reactions such as oxidation (most common), reduction and hydrolysis. There are three possible results of phase 1 metabolism. The drug becomes completely inactive. One or more of the metabolites are pharmacologically active, but less so than the original drug.
What is xenobiotic detoxification?
In general, xenobiotic detoxification involves the conversion of lipid-soluble substances to water-soluble, excretable metabolites. In Phase I detoxification, the toxin structure is enzymatically altered and rendered unable to interact with lipophilic target sites.
What are the phases of detoxification?
There are many processes of conjugation, including glutathionation, methylation, glucuronidation, sulfation, and acetylation. Each of these processes involves the addition of a different substance to a phase I end-product. Each requires specific nutrients, mostly amino acids, which we must obtain from our diet.
What is detoxification in biochemistry?
Definition. Detoxification or detoxication is a series of biochemical reactions to convert toxic compounds to less toxic and more easily excretable forms.
What is meant by biotransformation?
Biotransformation is the process by which a substance changes from one chemical to another (transformed) by a chemical reaction within the body. Metabolism or metabolic transformations are terms frequently used for the biotransformation process.
What are the phases of biotransformation?
Biotransformation Reaction Phases
| Phase I | Phase II |
|---|---|
| Oxidation | Sulfate conjugation |
| Reduction | Glucuronide conjugation |
| Hydrolysis | Glutathione conjugation |
| Acetylation | Amino acid conjugation |
What is the difference between Phase 1 and Phase 2 metabolism?
Phase I reactions of drug metabolism involve oxidation, reduction, or hydrolysis of the parent drug, resulting in its conversion to a more polar molecule. Phase II reactions involve conjugation by coupling the drug or its metabolites to another molecule, such as glucuronidation, acylation, sulfate, or glicine.
What is cytochrome P450?
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown.
What is the meaning of cytochromes?
Cytochromes are redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in electron transport chain and redox catalysis. They are classified according to the type of heme and its mode of binding.
What is cytochrome system?
The cytochrome chain of mitochondria is a multienzyme, membrane associated system, composed of some twenty polypeptides and nine metal redox centers, optimized during evolution to catalyze, in a controlled fashion, the transfer of reducing equivalents from dehydrogenases to oxygen and convert the free energy made …