In vitro glucuronidation of 3'-azido-3'-deoxythymidine by human liver. Role of UDP-glucuronosyltransferase 2 form. 1991

J F Rajaonarison, and B Lacarelle, and G De Sousa, and J Catalin, and R Rahmani
Institut National de la Santé et de la Recherche Médicale, Laboratoire de Toxicocinétique et Pharmaćocinetique, Faculté de Pharmacie, Marseille, France.

The glucuronidation of 3'-azido-3'-deoxythymidine (AZT) by human liver microsomes and human hepatocytes in culture has been studied in vitro to determine the UDP-glucuronosyltransferase (UDPGT) form conceivably involved in the AZT biotransformation process. The glucuronide of AZT was preliminarily identified through hydrolysis by beta-D-glucuronidase. Brij 58 was shown to be the best activator of AZT glucuronidation by human liver microsomes, as it increased the rate of glucuronide formation 3-fold. The UDPGT activities toward AZT measured in 29 different microsomal fractions was slightly variable among samples (79 to 268 nmol/hr/mg protein). The apparent KM value for AZT glucuronidation was about 5 mM. We sought to determine if various known UDPGT activities (i.e. p-nitrophenol UDPGT, 4-hydroxybiphenyl UDPGT, and DT1-UDPGT) in 18 microsomal samples were correlated with AZT-UDPGT activity. Experiments revealed that only 4-hydroxybiphenyl UDPGT activity was strongly correlated (r = 0.815, p less than 0.001) with AZT-UDPGT activity, whereas no correlation was found for the other UDPGT activities. To determine the isozyme conceivably involved in AZT glucuronidation, we studied the effect of various compounds on AZT glucuronidation. AZT glucuronidation was inhibited by numerous substrates of the UDPGT2, form: morphine (Ki = 1.8 mM), 4-hydroxybiphenyl (Ki = 0.92 mM), and ketoprofen (Ki = 0.75 mM), but also oxazepam, codeine, and chloramphenicol. p-Nitrophenol appeared to be an inhibitor, whereas acetaminophen had no effect. Bilirubin, aspirin, cimetidine, and acyclovir did not inhibit AZT glucuronidation. Since all the inhibitors tested except p-nitrophenol are known to be glucuronidated by the UDPGT2 form, our results strongly suggest the involvement of this isozyme in AZT glucuronidation.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D007527 Isoenzymes Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics. Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D003902 Detergents Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties. Cleansing Agents,Detergent Pods,Laundry Detergent Pods,Laundry Pods,Syndet,Synthetic Detergent,Agent, Cleansing,Agents, Cleansing,Cleansing Agent,Detergent,Detergent Pod,Detergent Pod, Laundry,Detergent Pods, Laundry,Detergent, Synthetic,Detergents, Synthetic,Laundry Detergent Pod,Laundry Pod,Pod, Detergent,Pod, Laundry,Pod, Laundry Detergent,Pods, Detergent,Pods, Laundry,Pods, Laundry Detergent,Synthetic Detergents
D005965 Glucuronates Derivatives of GLUCURONIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that include the 6-carboxy glucose structure. Glucosiduronates,Glucuronic Acids,Acids, Glucuronic
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001711 Biotransformation The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.
D014453 Glucuronosyltransferase A family of enzymes accepting a wide range of substrates, including phenols, alcohols, amines, and fatty acids. They function as drug-metabolizing enzymes that catalyze the conjugation of UDPglucuronic acid to a variety of endogenous and exogenous compounds. EC 2.4.1.17. Glucuronyltransferase,UDP Glucuronosyltransferase,17 beta-Hydroxysteroid UDP-Glucuronosyltransferase,4-Nitrophenol-UDP-Glucuronosyltransferase,7-Hydroxycoumarin UDP Glucuronyltransferase,Androsterone UDP-Glucuronosyltransferase,Bilirubin UDP-Glucuronyltransferase,Estrogen UDP-Glucuronosyltransferase,Estrone Glucuronyltransferase,Glucuronic Transferase,Morphine Glucuronyltransferase,UDP Glucuronyl Transferase,UDP-Glucuronic Acid 3-O-beta-D-Galactosyl-D-Galactose Glucuronosyltransferase,p-Nitrophenyl UDP-Glucuronosyltransferase,17 beta Hydroxysteroid UDP Glucuronosyltransferase,4 Nitrophenol UDP Glucuronosyltransferase,7 Hydroxycoumarin UDP Glucuronyltransferase,Androsterone UDP Glucuronosyltransferase,Bilirubin UDP Glucuronyltransferase,Estrogen UDP Glucuronosyltransferase,Glucuronosyltransferase, UDP,Glucuronyl Transferase, UDP,Glucuronyltransferase, 7-Hydroxycoumarin UDP,Glucuronyltransferase, Estrone,Glucuronyltransferase, Morphine,Transferase, Glucuronic,Transferase, UDP Glucuronyl,UDP Glucuronic Acid 3 O beta D Galactosyl D Galactose Glucuronosyltransferase,UDP Glucuronyltransferase, 7-Hydroxycoumarin,UDP-Glucuronosyltransferase, 17 beta-Hydroxysteroid,UDP-Glucuronosyltransferase, Androsterone,UDP-Glucuronosyltransferase, Estrogen,UDP-Glucuronosyltransferase, p-Nitrophenyl,UDP-Glucuronyltransferase, Bilirubin,p Nitrophenyl UDP Glucuronosyltransferase
D015215 Zidovudine A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by an azido group. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is a potent inhibitor of HIV replication, acting as a chain-terminator of viral DNA during reverse transcription. It improves immunologic function, partially reverses the HIV-induced neurological dysfunction, and improves certain other clinical abnormalities associated with AIDS. Its principal toxic effect is dose-dependent suppression of bone marrow, resulting in anemia and leukopenia. AZT (Antiviral),Azidothymidine,3'-Azido-2',3'-Dideoxythymidine,3'-Azido-3'-deoxythymidine,AZT Antiviral,AZT, Antiviral,BW A509U,BWA-509U,Retrovir,3' Azido 2',3' Dideoxythymidine,3' Azido 3' deoxythymidine,Antiviral AZT,BWA 509U,BWA509U

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