Detoxification Phase

TALALAY p (1991) Chemical Protection Against Cancer by Inducation of Electrophile Detoxification (phase 2) Enzymes Cellular Molec Targets Chemoprev, 1-11. 

Medications can play a prominent role in the treatment of alcohol use disorders (see Table 6.4). As noted earlier, they are widely used during the initial detoxification phase of treatment. In recent years, psychiatric medications have taken on a more prominent role during the rehabilitation phase of treatment. 

Enzyme induction and enhancement of detoxification Phase ii enzymes Glutathione peroxidase Catalase... 

Treatment of drug addicts can be sqDarated into two phases detoxification and relapse prevention. Detoxification programs and treatment of physical withdrawal symptoms, respectively, is clinically routine for most drugs of abuse. However, pharmacological intervention programs for relapse prevention are still not veiy efficient. 

NHO c w and JEFFERY E (2001) The synergistic upregulation of phase II detoxification enzymes by glucosinolate breakdown products in cruciferous vegetables , Toxicol Appl Pharmacol, 174 146-52. 

Carney CK.HarrySR,Sewell SL.WrightDW (2007) Detoxification Biominerals. 270 155-185 Castagner B, Seeberger PH (2007) Automated Solid Phase Oligosaccharide Synthesis. 278 289-309... 

Adsorption is a physicochemical process whereby ionic and nonionic solutes become concentrated from solution at solid-liquid interfaces.3132 Adsorption and desorption are caused by interactions between and among molecules in solution and those in the structure of solid surfaces. Adsorption is a major mechanism affecting the mobility of heavy metals and toxic organic substances and is thus a major consideration when assessing transport. Because adsorption is usually fully or partly reversible (desorption), only rarely can it be considered a detoxification process for fate-assessment purposes. Although adsorption does not directly affect the toxicity of a substance, the substance may be rendered nontoxic by concurrent transformation processes such as hydrolysis and biodegradation. Many chemical and physical properties of both aqueous and solid phases affect adsorption, and the physical chemistry of the process itself is complex. For example, adsorption of one ion may result in desorption of another ion (known as ion exchange). 

Carotenoids have been found to exert numerous other effects of potential importance for the RPE. Carotenoids can activate transcription pathways (Ben-Dor et al., 2005 Kalariya et al., 2008 Palozza et al., 2006 Sharoni et al., 2004) for example, by activation of the antioxidant response element (ARE) (Ben-Dor et al., 2005 Sharoni et al., 2004). The ARE is an enhancer sequence responsible for the expression of many phase-II detoxification and antioxidant genes. Thus carotenoids may upregulate cellular antioxidant defenses. 

Researchers focused on the metabolically competent human hepatoma cell line HepG2 as a model of human liver. HepG2 cells are a well-known hepatoma cell line that retains many of the morphological characteristics of liver parenchymal cells. This model is often used as a useful tool for HRA/ERA-oriented chemical risk assessment due to the expression of antioxidant and xenobiotic metabolizing enzymes (in particular phase I and phase II enzymes responsible for the bioactivation/detoxification of various xenobiotics) that can be induced or inhibited by dietary and non-dietary agents [28-30]. 

Stimulation of phase II detoxification enzymes (Kong and others 2001 Walle and Walle 2002). 

Virtually all organisms possess biotransformation or detoxification enzymes that convert lipophilic xenobiotics to water-soluble and excretable metabolites (Yu et al. 1995). In the metabolic process, PAHs are altered by Phase I metabolism into various products such as epoxides, phenols,... 

GSTs contain a site that accommodates GSH ("GSH binding domain") [31], where the proton of the GSH s thiol group is abstracted, promoting the nucleophilic conjugation of the thiolate to electrophilic substrates. The resulting adducts become more water-soluble and are then eliminated by a phase II detoxification mechanism. 

In order for allelochemicals to enter the body of a herbivore, absorption must occur across the gut lining. Curtailing the initial absorption of dietary allelochemicals may be a herbivore s first line of defense against plant toxins. Studies have citied the lack of absorption or metabolism of lipophilic plant secondary metabolites (i.e., terpenes), conducive to phase I or II detoxification, in the gut of terrestrial herbivores rather these compounds are excreted unchanged in the feces (Marsh et al. 2006b). While physical barriers or surfactants have been used to explain this limited adsorption in both marine and terrestrial herbivores (Lehane 1997 Barbehenn and Martin 1998 Barbehenn 2001 for review of marine herbivores, see Targett and Arnold 2001), active efflux of plant allelochemicals out of enterocytes into the gut lumen has received limited attention until now. 

In addition to the common pathways, glycolysis and the TCA cycle, the liver is involved with the pentose phosphate pathway regulation of blood glucose concentration via glycogen turnover and gluconeogenesis interconversion of monosaccharides lipid syntheses lipoprotein formation ketogenesis bile acid and bile salt formation phase I and phase II reactions for detoxification of waste compounds haem synthesis and degradation synthesis of non-essential amino acids and urea synthesis. 

Urea ((NH2)2CO), a small and highly water soluble molecule, is an end product of amine and ammonia nitrogen metabolism and as such represents an example of biodetoxification (Section 6.4). The process is discussed in this section because it illustrates a genuine de novo biosynthetic pathway rather than detoxification involving chemical modification, via phase I and phase II reactions, of a pre-existing molecule as is the case for haem or steroid hormones. 

The following section discusses the different types and phases of microbial degradation of organic pollutants present at aqueous-solid phase interfaces. This includes a discussion of growth-linked biodegradation, acclimation, detoxification, activation, defusing, threshold, and co-metabolism. 

Quinones and other xenobiotics are metabolized primarily in the liver, and the end products are water-soluble compoimds that are excreted from the body. The first step in metabolism is usually an oxidative process (phase I detoxification), after which further oxidation and conjugation can occur (phase II detoxification). Although those reactions normally yield easily excreted products, some steps in the metabolic pathway may generate metabolites that are more toxic than the parent comporuid. 

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