Biotransformation metabolite conversion

In tissues, its monomethylated metabolite may undergo further biotransformation. Ultimately, conversion into inorganic mercury enables the metal to bind to glutathione for biliary excretion. However, much of this complex can also be reabsorbed by the gastrointestinal tract. Such bile-hepatic recycling permits redistribution of mercury. 

The oxidation of OPs can bring detoxication as well as activation. Oxidative attack can lead to the removal of R groups (oxidative dealkylation), leaving behind P-OH, which ionizes to PO . Such a conversion looks superficially like a hydrolysis, and was sometimes confused with it before the great diversity of P450-catalyzed biotransformations became known. Oxidative deethylation yields polar ionizable metabolites and generally causes detoxication (Eto 1974 Batten and Hutson 1995). Oxidative demethy-lation (0-demethylation) has been demonstrated during the metabolism of malathion. 

Biotransformation involves the chemical alteration of a molecule to alter its effects. This often terminates the pharmacological effects of a drug, but active metabolites are produced in some cases. Biotransformation also changes the ease with which a drug is eliminated. This involves conversion of the drug to a more hydrophilic metabolite that enhances renal excretion. Although this process pertains to most drugs, it probably... 

Dealkylations have been used in the regioselective conversion of methoxyaryl groups to phenols in natural products, particularly alkaloids 1471 such as papaverine (30), and in the production of mammalian metabolites by microbial biotransformation, as exemplified by the biotransformation of bisprolol (4). 

The majority of compounds that enter the organism require metabolism in order to be excreted. If the parent compound is responsible for the toxicity and its metabolites are less toxic, an increased biotransformation rate will reduce the toxicity, and conversely. However, if the chemical s toxicity is mainly due to its metabolite, stimulating the biotransformation will enhance the toxicity. 

Biotransformation. Steroid hormones and bilirubin, as well as drugs, ethanol, and other xenobiotics are taken up by the liver and inactivated and converted into highly polar metabolites by conversion reactions (see p. 316). 

Some drugs are eliminated from the body unchanged, but most drugs undergo biotransformation. Biotransformation enables a drug to be converted to forms readily excreted by the liver and kidney, whereas sometimes it enables a drug to be converted to an active form. These conversions almost always result in metabolites that are more polar than the parent drug. 

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