Synthesis and Characterization of Quaternary Ammonium-Linked Glucuronide Metabolites of Drugs with an Aliphatic Tertiary Amine Group

Luo, Haoming; Hawes, E. M.; McKay, G.; Midha, K. K.

doi:10.1002/jps.2600811107

Cited by 21 publications

(13 citation statements)

References 6 publications

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“…Also by use of 10 commercially available recombinant enzymes, the UGT(s) responsible for the formation of the N-1 glucuronides of nicotine isomers and S(Ϫ)-cotinine were investigated. (Vashishtha et al, 2000) and trifluoperazine N4Ј-glucuronide, (Luo et al, 1992) were synthesized by modification of previously reported procedures, and S(Ϫ)-cotinine N1-glucuronide was purchased from Toronto Research Chemicals Inc. (Toronto, ON, Canada).…”

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confidence: 99%

N-Glucuronidation of Nicotine and Cotinine in Human: Formation of Cotinine Glucuronide in Liver Microsomes and Lack of Catalysis by 10 Examined UDP-Glucuronosyltransferases

Ghosheh

Hawes²

2002

Drug Metab Dispos

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ABSTRACT:Two predominant human glucuronide metabolites of nicotine result from pyridine nitrogen atom conjugation. The present objectives included determination of the kinetics of formation of S(؊)-cotinine N1-glucuronide in pooled human liver microsomes and investigation of the UDP-glucuronosyltransferases (UGTs) involved in N-glucuronidation of nicotine isomers and S(؊)-cotinine by use of recombinant enzymes (UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT1A10, UGT2B7, and UGT2B15). Quantification was by radiochemical high-performance liquid chromatography with use of radiolabeled substrates. S(؊)-Cotinine N1-glucuronide formation in human liver microsomes was proven by comparing the chromatographic behaviors and electrospray ionization-mass spectral characteristics of the metabolite with a synthetic reference standard. This glucuronide was formed by one-enzyme kinetics with K m and V max values of 5.4 mM and 696 pmol/min/mg, respectively, and the apparent intrinsic clearance value (V max/Km ) was 9-fold less than that previously determined for S(؊)-nicotine N1-glucuronide (0.13 versus 1.2 l/min/mg) using the same pooled microsomes. This comparison of values is consistent with the observation that on smoking cigarettes, although the average S(؊)-cotinine plasma levels usually far exceed S(؊)-nicotine levels, the urinary recovery of S(؊)-cotinine N1-glucuronide only averages 3-fold greater than for S(؊)-nicotine N1-glucuronide. None of the UGTs examined catalyzed the N-glucuronidation of S(؊)-nicotine, R(؉)-nicotine, and S(؊)-cotinine, including UGT1A3and UGT1A4, the only isoforms known to catalyze many substrates at a tertiary amine. Also, neither S(؊)-nicotine or S(؊)-cotinine affected enzyme inhibition of trifluoperazine, a UGT1A4 substrate. It would appear that the same, as yet unexamined, UGT catalyzes the N-glucuronidation of both cotinine and nicotine.The major routes of metabolism of nicotine in human involve oxidation and glucuronidation. The former metabolic routes have been thoroughly investigated, including establishing that the predominant proportion of nicotine metabolism is accounted for by routes of metabolism involving the lactam oxidation product cotinine as an intermediate and that CYP2A6 dominates as the main cytochrome P450 enzyme involved in catalysis (Nakajima et al., 1996a(Nakajima et al., , 1996bMessina et al., 1997;Murphy et al., 1999). In contrast, most studies of the glucuronidation routes of nicotine metabolism involve investigation of in vivo formation in human. It is established that three glucuronide metabolites account for 25 to 30% of the urinary metabolites after either inhalation or transdermal administration of nicotine. These three metabolites are the quaternary ammonium-linked glucuronides of S(Ϫ)-nicotine and S(Ϫ)-cotinine (Fig. 1), and the Oglucuronide of trans-3Ј-hydroxycotinine Caldwell et al., 1992;Benowitz et al., 1994). Further knowledge has been lacking regarding these three glucuronide metabolites, including the apparent formation kinetics and the UDP-...

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confidence: 99%

N-Glucuronidation of Nicotine and Cotinine in Human: Formation of Cotinine Glucuronide in Liver Microsomes and Lack of Catalysis by 10 Examined UDP-Glucuronosyltransferases

Ghosheh

Hawes²

2002

Drug Metab Dispos

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“…[1][2][3] More recently it has been recognised that structurally similar zwitterionic N þ -glucuronides, of general structure 2, are important metabolites for a wide range of drugs that contain a tertiary amino group. 4,5 Thus amitriptyline 3, 5 imipramine 4 5 and tamoxifen 5 6 are all metabolised at least in part in this way and a very recent report confirmed the isolation of a similar metabolite of 1-hydroxymidazolam. 7 N-Glucuronide metabolites are often unique to humans and are therefore not detected in pre-clinical studies.…”

Section: Introductionmentioning

confidence: 67%

Syntheses and structures of anomeric quaternary ammonium β-glucosides and comments on the anomeric C–N bond lengths

et al. 2009

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“…The N-glucuronidation metabolite of SEN was synthesized by following an established method (Luo et al, 1992). In brief, all of the hydroxyls of the glucuronic acid were protected via acetylation and then the anomeric acetylhydroxyl group with a bromine atom was substituted, and the brom-acetylglucuronic acid was used to react with pure SEN to prepare the sugar-acetylated conjugation product.…”

Section: Methodsmentioning

confidence: 99%

Identification of the UDP-Glucuronosyltransferase Isozyme Involved in Senecionine Glucuronidation in Human Liver Microsomes

He¹,

Liu²,

Zhang³

et al. 2010

Drug Metab Dispos

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ABSTRACT:Senecionine (SEN) is a representative of the hepatotoxic pyrrolizidine alkaloids. Although phase I metabolism for cytochrome P450-mediated metabolic activation of SEN was investigated extensively, phase II metabolism for glucuronidation of this compound has not been investigated until now. In our present study, one unique glucuronidation product of SEN in human liver microsomes (HLMs) was identified as SEN N-glucuronide using an authentically synthesized product for which the structure was identified via 1 H Hepatotoxic pyrrolizidine alkaloids (HPAs) are widely distributed in higher plants around the world (Roeder, 1995) and are highly toxic to wildlife (Hartmann, 2008), livestock (Nobre et al., 2005Stegelmeier et al., 2009), experimental animals (Tang et al., 2007, and humans (Stegelmeier et al., 1999) by multiple pathways such as consumption of foods (Crews et al., 1997;Prakash et al., 1999) and use of traditional herbs (Roeder, 1995(Roeder, , 2000 containing HPAs.In general, HPAs induce liver intoxication through metabolic activation by liver P450 enzymes, especially CYP3A4, to form reactive dehydrogenated pyrrolic esters (Couet et al., 1996) that can covalently conjugate with proteins and nucleic acids to evoke various toxicities such as cell necrosis, veno-occlusive diseases, and carcinogenicity (Fu et al., 2004). However, other detoxification pathways of HPAs were also observed, such as nonenzymatic dehydrogenated pyrrole-glutathione conjugation (Lin et al., 2000), N-oxidation (Huan et al., 1998) catalyzed by flavin-containing monooxygenase, and hydrolysis catalyzed by guinea pig hepatic carboxylesterase (Dueker et al., 1992).As the most important phase II drug-metabolizing enzymes, UDPglucuronosyl transferases (UGTs) play a very important role in the elimination of xenobiotic and endogenous substances and nearly half of the known phase II metabolism of the top 200 prescribed drugs in United States is catalyzed by them (Williams et al., 2004). However, whether UGTs participate in the metabolism of HPAs is still not clear.In our preliminary experiment, senecionine (SEN) (Fig. 1), a representative HPA isolated from Senecio vulgaris, underwent glucuronidation by UGTs in human liver microsomes (HLMs). As a competitive metabolic pathway of P450-mediated metabolic activation, glucuronidation is promising as a new detoxification pathway of SEN, and the UGT isozyme(s) participating in SEN glucuronidation needs to be clarified.The purpose of this study was to authenticate the conjugated site of SEN by glucuronic acid and to identify the UGT isozyme(s) partici-

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Synthesis and Characterization of Quaternary Ammonium-Linked Glucuronide Metabolites of Drugs with an Aliphatic Tertiary Amine Group

Cited by 21 publications

References 6 publications

N-Glucuronidation of Nicotine and Cotinine in Human: Formation of Cotinine Glucuronide in Liver Microsomes and Lack of Catalysis by 10 Examined UDP-Glucuronosyltransferases

N-Glucuronidation of Nicotine and Cotinine in Human: Formation of Cotinine Glucuronide in Liver Microsomes and Lack of Catalysis by 10 Examined UDP-Glucuronosyltransferases

Syntheses and structures of anomeric quaternary ammonium β-glucosides and comments on the anomeric C–N bond lengths

Identification of the UDP-Glucuronosyltransferase Isozyme Involved in Senecionine Glucuronidation in Human Liver Microsomes

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