Biotransformation pathway

Most of these enzymes have steroids or fatty acids as their substrates (Table 1). Many P450s in endogenous biotransformation pathways are characterized by usually very narrow substrate and product specificity and by tight regulatory systems, especially those involved in steroid hormone biosynthesis. 

Kaplan DL (1990) Biotransformation pathways of hazardous energetic organo-nitro compounds. In Biotechnology and Biodegradation (Eds D Kamely, A Chakrabarty and GS Omenn), Vol. 4, pp. 155-181. Gulf Publishing Company, Houston. 

Kassahun, K. Pearson, P. G. Tang, W. McIntosh, I. Leung, K. Elmore, C. Dean, D. Wang, R. Doss, G. Baillie, T. A. Studies on the metabolism of troglitazone to reactive intermediates in vitro and in vivo. Evidence for novel biotransformation pathways involving quinone methide formation and thiazolidinedione ring scission. Chem. Res. Toxicol. 2001, 14, 62-70. 

Other chlorotriazines (simazine, propazine, terbuthylazine) follow the same biotransformation pathway of atrazine therefore, urinary excretion of bi-dealkylated, deisopropylated, and deethylated metabolites is not compound specific. When simultaneous exposure to different chlorotriazines occurs, the unmodified compound measured in urine, even though it represents a minor portion of the absorbed dose, may be useful for a qualitative confirmation of exposure. 

Bromocriptine is rapidly and completely metabolised in animals and man. The major components of the urinary metabolites have been identified as 2-bromo-lysergic acid and 2-bro-mo-isolysergic acid. Apart from the hydrolytic cleavage of the amine bond and the isomerization at position 8 of the lysergic acid moiety, a third principal biotransformation pathway consists in the oxidative attack of the molecule at the proline fragment of the peptide part, predominantly at position 8, giving rise to the formation of a number of hydroxylated and further oxidized derivatives of bromocriptine, and in addition of conjugated derivatives thereof. 

The species differences in biotransformation pathways, rates of elimination, and intrinsic hepatic clearance of esfenvalerate and deltamethrin using rat and human liver microsomes were examined [33]. Esfenvalerate was eliminated primarily via NADPH-dependent oxidative metabolism in both rat and human liver microsomes. The CLint of esfenvalerate was estimated to be threefold greater in rodents than in humans on a per kg body weight basis. Deltamethrin was also eliminated primarily via NADPH-dependent oxidative metabolism in rat liver microsomes however, in human liver microsomes, deltamethrin was eliminated almost entirely via... 

Studies on the metabolism of troglitazone to reactive intermediates in vitro and in vivo. Evidence for novel biotransformation pathways involving quinone methide formation and thiazolidinedione ring scission. Chemical Research in Toxicology, 14 (1), 62—70. 

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. 

Valuable metabolic insights have been gained from in-depth studies of phenytoin (diphenylhydantoin, 10.21), whose main biotransformation pathway is by cytochrome P450 catalyzed phenyl oxidation. Incubations with rat liver 9000 g supernatant produced the para-phenol (4 -hydroxyphenytoin) as the major metabolite, and the dihydrodiol in smaller proportions. Minute amounts of other metabolites were also detected, e.g., the meto-phenol and the 3-O-mclhylcalcchol. Studies in rats confirmed the urinary excretion, in decreasing order of importance, of the para-phenol, the dihydrodiol, and the 3-O-mclhylcalcchol metabolites [78][79],... 

M. Comet, A. Callaerts, U. Jorritsma, H. Bolt, A. Vercruysse, V. Rogiers, Species-Dependent Differences in Biotransformation Pathways of 2-Methylpropene (Isobutene) , Chem. Res. Toxicol. 1995, 8, 987 - 992. 

Surh YJ, Lee SS. (1992). Enzymatic reduction of shogaol a novel biotransformation pathway for the alpha, beta-unsaturated ketone system. Biochem Int. 27(1) 179-87. 

Similar or identical biotransformation pathways, including ability to induce or inhibit biotransformation enzymes... 

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