Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Biotransformation pathways factors affecting

This section focuses on (1) a discussion of the overall process of biodegradation, (2) a review of the different types, aspects and phases of biodegradation of several classes of organic pollutants, (3) an examination of the environmental factors affecting biodegradation and biotransformation mechanisms, and (4) a description of the different biodegradation and biotransformation pathways. [Pg.331]

In addition to the physicochemical factors that affect xenobiotic metabolism, stereochemical factors play an important role in the biotransformation of drugs. This involvement is not unexpected, because the xenobiotic-metabolizing enzymes also are the same enzymes that metabolize certain endogenous substrates, which for the most part are chiral molecules. Most of these enzymes show stereoselectivity but not stereospecificity in other words, one stereoisomer enters into biotransformation pathways preferentially but not exclusively. Metabolic stereochemical reactions can be categorized as follows substrate stereoselectivity, in which two enantiomers of a chiral substrate are metabolized at different rates product stereoselectivity, in which a new chiral center is created in a symmetric molecule and one enantiomer is metabolized preferentially and substrate-product stereoelectivity, in which a new chiral center of a chiral molecule is metabolized preferentially to one of two possible diastereomers (87). An example of substrate stereoselectivity is the preferred decarboxylation of S-a-methyIdopa to S-a-methyIdopamine, with almost no reaction for R-a-methyIdopa. The reduction of ketones to stereoisomeric... [Pg.480]

Low et al. (2004) have proposed a model to explain thioacetamide-induced hepatotox-icity and cirrhosis in rat livers. The pathways of thioacetamide-induced liver fibrosis were found to be initiated by thioacetamide S-oxide derived from the biotransformation of thioacetamide by the microsomal flavin-adenine nucleotide containing monooxygenase and cytochrome P450 systems and involve oxidative stress and depletion of succinyl-CoA, thus affecting heme and iron metabolism. Karabay et al. (2005) observed such hepatic damage in rats with elevation of total nitrite level in livers and decrease in arginase activity. The authors have reported that nitrosative stress was essentially the critical factor in thioacetamide-induced hepatic failure in rats. [Pg.879]


See other pages where Biotransformation pathways factors affecting is mentioned: [Pg.311]    [Pg.66]    [Pg.1868]    [Pg.40]    [Pg.694]    [Pg.282]    [Pg.93]    [Pg.109]   
See also in sourсe #XX -- [ Pg.311 ]




SEARCH



Biotransformation pathways

© 2024 chempedia.info