Biotransformation xenobiotics

Watkins, J. and Klaassen, C. (1986). Xenobiotic biotransformation in livestock Comparison to other species commonly used in toxicity testing. J. Anim. Sci. 63 933-942. 

Croci, T. and Williams, G.M. (1985). Activities of several phase I and phase II xenobiotic biotransformation enzymes in cultured hepatocytes from male and female rats. Biochem. Pharm. 17(34) 3029-3035. 

McQueen, C.A. and Williams, G.M. (1987). Toxicology studies in cultured hepatocytes from various species. In The Isolated Hepatocyte Use in Toxicology and Xenobiotic Biotransformation (Rauckman, E.J. and Padilla, G.M., Eds.). Academic Press, Orlando, FL, pp. 51-67. 

With respect to drug-metabolizing enzymes, the majority of the CYPs responsible for phase I metabolism are concentrated in liver. The CYPs considered here are all found in the endoplasmic reticulum (isolated as microsomes ). Of the 18 human CYP families known, the bulk of xenobiotic biotransformation processes are carried out by enzymes from the CYP1, CYP2 and CYP3 families. In humans, realistically,... 

Chambers, J. E., Yarbrough, J. D. Xenobiotic biotransformation systems in fishes. Comp. Bioahem. Physiol. (1976)... 

Further, by virtue of their larger livers, the R fish have a greater xenobiotic biotransformation potential. However, the in vivo studies show few consistent differences in metabolism between the two populations. Biotransformation may be a major contributory factor in mosquitofish resistance to other pesticides, for example, organophosphorus and botanical insecticides, since the level of resistance to these chemicals is very low (4 fold or less) 08,20,21). However, biotransformation does not appear to play a major role in organochlorine insecticide resistance. 

Parkki MG, Marniemi J, Vainio H Action of styrene and its metabolites styrene oxide and styrene glycol on activities of xenobiotic biotransformation enzymes in rat liver in vivo. Toxicol Appl Pharmacol 38 59-70, 1976... 

Drew R Miners JO (1984) The effects of buthionine sulphoximine (BSO) on glutathione depletion and xenobiotic biotransformation. Biochem Pharmacol. 33 2989-2994. 

Lipophilic materials require intracellular carrier proteins to be optimally mobilized, just as they required transport proteins in the blood (Figure 10.3). Several intracellular carrier proteins that mobilize specific endogenous chemical have been characterized, although less is known of which proteins typically mobilize xenobiotics. Some of the cytosolic glutathione S-transferase proteins have been shown to noncatalytically bind xenobiotics and to be coordinately induced along with xenobiotic biotransformation enzymes and efflux transporters, suggesting that these proteins may function to mobilize xenobiotics. 

Table 2 Examples of Clinically Relevant Substrates, Inhibitors, and Inducers of the Major Human Liver Microsomal P450 Enzymes Involved in Xenobiotic Biotransformation... 

The testes have xenobiotic biotransformation capabifities within both Leydig and Sertoli cells (Thomas and Thomas, 2001). While many toxicants and/or their metabofites are capable of producing relatively nonspecific effects, such as... 

Heinonen T, Elovaara E, Sade L., et al. 1983. Effect of various solvents on the xenobiotic biotransformation in the liver and the kidneys of the rat A comparative study. In Rydstrom J, Montelius J, Bengtsson M, eds. Extrahepatic drug metabolism and chemical carcinogenesis. New York, NY Elsevier Science Publishers, 29-33. 

Andersson, T., B.-E. Bengtsson, L. Forlin, J. Hardig, and A. Larsson. 1987. Long-term effects of bleached kraft mill effluents on carbohydrate metabolism and hepatic xenobiotic biotransformation enzymes in fish. Ecotoxicol. Environ. Saf. 13 53-60. 

TARLOFF, J.B., GOLDSTEIN, R.S. and HOOK, J.B. (1990) Xenobiotic biotransformation by the kidney pharmacological and toxicological aspects. In Progress in Drug Metabolism, Vol. 12, edited by G.G.Gibson (London Taylor Francis). 

The wide array of enzyme families, subfamilies, and isoforms that mediates xenobiotic biotransformations serves as an important defense mechanism to protect the body against a dazzling variety of xenobiotic insults. Nebert (University of Cincinnati Medical Center) once drew a broad parallel between the immune system and the drug metabolizing enzymes, noting that both systems are adaptive and are capable of protecting the body against diverse molecular species. 

Juchau MR, Lee QP, Fantel AG (1992) Xenobiotic biotransformation/bioactivation in organogenesis-stage conceptal tissues implications for embryotoxicity and teratogenesis. Drug Metab Rev 24 195-238... 

Thies, F, Backhaus, T, Bossmann, B, Grimme, LH, Xenobiotic biotransformation in unicellular green algae. Involvement of cytochrome P450 in the activation and selectivity of the pyridazinone pro-herbidde metflura-zon. Plant Physiol. 112, 361-370 (1996). 

Schlenk D, Buhler DR (1989) Xenobiotic biotransformation in the Pacific oyster Crassostrea gigas). Comp Biochem Physiol 94C 469-475... 

As it has been known, no systematic reviews have been undertaken to assess the role of xenobiotic biotransformation in colon, in particular in what concerns anthocyanins. 

McCloskey (64) has directed attention to the characterization of nucleic acids by MS. These include nucleic acid photoproducts, radical induced products, those modified by xenobiotic biotransformation, new and naturally occurring nucleosides, specially found in RNA, methylated bases, stable isotopes, and interface between MS and liquid chromatography systems. 

Most living beings have the capacity to metabolize xenobiotics by the process denominated biotransformation (Tuvikene, 1995). Biotransformation is characterized as a conjunct of enzymatic reactions, responsible for the conversion of the liposoluble substances in hydrosoluble facilitating, thus, their excretion process. However, although the purpose of the xenobiotics biotransformation is detoxification not always the originated metabohte is less toxic than the own chemical. Thus, xenobiotics biotransformation can increase the toxicity of the chemical products by the formation of electrophilic metabolites, extremely reactive, which can present potential to bind, covalently, with macromolecules inside the cells with DNA, RNA and proteins, which can result in several alterations such as disturbance in the immime system, mutations and even the organism death (Stanley, 1992,1994 Landis and Yu, 1998 Guecheva and Henriques, 2003). 

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