Synthesis and Hepatic Transport of Strongly Fluorescent Cholephilic Dipyrrinones.

Woydziak, Zachary R.; Boiadjiev, Stefan E.; Norona, Wilma S.; McDonagh, Antony F.; Lightner, David A.

doi:10.1002/chin.200603162

Cited by 3 publications

(5 citation statements)

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“…17,18,20 Animal procedures, HPLC methods, and the provenance of the animals used also have been described in detail previously. 28 All animal studies were in compliance with institutional guidelines and approval requirements. For metabolism studies, each pigment (∼0.25 mg, accurately weighed on a microbalance) was dissolved in 0.1 mL of dimethyl sulfoxide (DMSO) or argon-degassed 0.1 M NaOH and the optically clear solution was slowly and quantitatively diluted into 1 mL of rat serum using a finely drawn out Pasteur pipet.…”

Section: Methodsmentioning

confidence: 99%

“…Hydration and bile flow were maintained by infusion of a bile salt/lipid solution. 28 Bile was collected in 20-µL aliquots into glass tubes and flash-frozen immediately with dry ice, and bile flow rates were estimated gravimetrically. Frozen samples were stored at -70 °C pending HPLC analysis, when they were mixed with 80 µL of eluent and microfuged.…”

Section: Methodsmentioning

confidence: 99%

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Influence of Conformation and Intramolecular Hydrogen Bonding on the Acyl Glucuronidation and Biliary Excretion of Acetylenic Bis-Dipyrrinones Related to Bilirubin

McDonagh

Lightner

2007

J. Med. Chem.

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Glucuronidation and transporter-mediated efflux into bile are important in the elimination of xeno- and endobiotics, including the natural biladienone pigment bilirubin. The mechanisms of these processes and the structural factors that dictate whether cholephilic compounds are excreted directly in bile or require prior glucuronidation are poorly understood. To investigate effects of molecular shape and intramolecular hydrogen bonding on the interplay between direct excretion and glucuronidation in the liver, we studied a series of novel synthetic exploded and homologated bilirubin analogues. These include dicarboxylic mono- and diacetylenic tetrapyrroles with linear shapes that are unable to adopt the folded ridge-tile conformations that are crucially important in bilirubin metabolism. Intramolecular hydrogen bonding was varied by adjusting the alkyl chain lengths of the pendent carboxyl groups, and preferred conformations were predicted by molecular dynamics calculations. Metabolism studies were done in rats, including Gunn rats, congenitally deficient in UGT1 glucuronosyl tranferases, and TR- rats, deficient in the canalicular transporter Mrp2 (Abcc2). The results show strikingly that minor, seemingly inconsequential, changes in constitution, amplified by their influence on hydrogen bonding and molecular conformation, can profoundly influence competing clearance pathways in the liver, an effect that is unlikely to be restricted to bis-dipyrrinone carboxylic acids. Exposed carboxyl groups seem to favor the direct route of elimination, whereas the potential for carboxyl infolding by hydrogen bonding seems to favor glucuronidation. The results also show that molecular shape is less important in the hepatic glucuronidation and biliary excretion of bilirubin and of this series of acids than the capacity for intramolecular hydrogen bonding.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Influence of Conformation and Intramolecular Hydrogen Bonding on the Acyl Glucuronidation and Biliary Excretion of Acetylenic Bis-Dipyrrinones Related to Bilirubin

McDonagh

Lightner

2007

J. Med. Chem.

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“…Bilirubin ditaurate (10) was from Frontier Scientific (Logan, UT) and di-n-octylamine from Sigma-Aldrich (St. Louis, MO). Animal procedures, sources of rats, and HPLC methods were as detailed elsewhere (Woydziak et al, 2005;McDonagh and Lightner, 2007). For biliary excretion studies, pigments (ϳ0.25 mg, accurately weighed), freshly dissolved in argon-degassed 0.1 M NaOH, were quantitatively diluted into 1 ml of rat serum.…”

Section: Methodsmentioning

confidence: 99%

Slipping Past UGT1A1 and Multidrug Resistance-Associated Protein 2 in the Liver: Effects of Steric Compression and Hydrogen Bonding on the Hepatobiliary Elimination of Synthetic Bilirubins

McDonagh

Boiadjiev²,

Lightner³

2008

Drug Metab Dispos

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ABSTRACT:The hepatobiliary metabolism and excretion of three isomeric bilirubin analogs with propanoic replaced by benzoic acid side-chains were studied in the rat. Despite their isomeric relationship and similar constitutions, the three analogs were metabolized quite differently from each other and from bilirubin. In the di-o-benzoic compound, steric hindrance involving the phenyl groups reinforces intramolecular hydrogen bonding of the two carboxyl groups. This compound is considerably less polar than bilirubin on reversephase high-performance liquid chromatography and, like bilirubin, was not excreted in bile in UGT1-deficient (Gunn) rats. But, quite unlike bilirubin, it was not glucuronidated or excreted in bile in normal rats. In contrast to both bilirubin and the di-o-benzoic isomer, the more polar m-and p-isomers, in which intramolecular hydrogen bonding of carboxyl groups is sterically difficult, were excreted rapidly in bile in unchanged form in both normal and Gunn rats. However, only one of them, the di-m-isomer, was excreted rapidly and unchanged in bile in rats (TR ؊ rats) congenitally deficient in the canalicular ATP-binding cassette transporter Mrp2. The marked differences in hepatobiliary metabolism of the three isomers studied can be rationalized on the basis of their computed three-dimensional structures and minimum-energy conformations and the remote effects of steric compression on intramolecular hydrogen bonding.Bilirubin (1) (Fig. 1) is formed in mammals by reduction of biliverdin (2), end product of most heme catabolism. It is insoluble in water, lipophilic, extensively protein-bound in plasma, and, unlike biliverdin, requires phase-2 metabolism, mainly to mono-and diglucuronides, for elimination. Once used as a liver function test (Harrop and Barron, 1931;Kornberg, 1942), bilirubin is a constituent of several Asian traditional medicines (McDonagh, 1990), and its antioxidant/anti-inflammatory properties are currently attracting attention (Stocker et al., 1987;Stocker, 2004; Ollinger et al., 2007a,b). Historically, bilirubins have been useful for investigating mechanisms of acyl glucuronidation, membrane transport, and hepatobiliary excretion. Bilirubin and its two monoglucuronides are isozyme-specific substrates for the glucuronosyl transferase UGT1A1 (Owens et al., 2005), and its three acyl glucuronides are classic examples of compounds that depend wholly on the ATP-binding cassette transporter MRP2 (ABCC2) for elimination in bile (Nies and Keppler, 2007). Deficiencies of UGT1A1 cause neonatal jaundice, Gilbert's and CriglerNajjar syndromes (Kaplan and Hammerman, 2005), and congenital deficiency of MRP2 underlies the rare Dubin-Johnson syndrome (Nies and Keppler, 2007). Studies on bilirubin glucuronides led to the discovery that acyl glucuronides of many drugs are reactive, potentially toxic, metabolites (Smith et al., 1986), and studies on bilirubin analogs have revealed how subtle changes in molecular conformation can profoundly influence hepatic metabolism (McDonagh and Lightner, 1991;...

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“…4) that is taken up by unknown hepatic transport proteins and is excreted into bile by Mrp2 and an Mrp2-independent pathway. 16 The hepatobiliary disposition of this substrate was evaluated in automated SCRH studies, and results consistently showed significant accumulation (cells + bile = 180 ± 27 pmoles/mg protein; cells= 110 ± 9.2 pmoles/mg protein) and a relatively high BEI (41 ± 8.6) in SCRH (n = 6), which are both desirable probe quantities.…”

Section: Evaluation Of a Fluorescent Probe Using Scrhmentioning

confidence: 95%

“…[13][14][15] Sulfoglow 1a was selected as a novel substrate to evaluate with automated studies because it is a water-soluble, fluorescent molecule with some structural similarities to bilirubin, and it is rapidly taken up and excreted intact following intravenous injection into rats. 16 Bilirubin and its glucuronide conjugates are well-recognized markers of hepatic dysfunction. 17 Here, we demonstrate the use of the applications described above using SCRH in a fully automated format.…”

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confidence: 99%

Automated Applications of Sandwich-Cultured Hepatocytes in the Evaluation of Hepatic Drug Transport

Perry¹,

Smith²,

Claire³

et al. 2011

SLAS Discovery

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Predictions of the absorption, distribution, metabolism, excretion, and toxicity of compounds in pharmaceutical development are essential aspects of the drug discovery process. B-CLEAR is an in vitro system that uses sandwich-cultured hepatocytes to evaluate and predict in vivo hepatobiliary disposition (hepatic uptake, biliary excretion, and biliary clearance), transporterbased hepatic drug-drug interactions, and potential drug-induced hepatotoxicity. Automation of predictive technologies is an advantageous and preferred format in drug discovery. In this study, manual and automated studies are investigated and equivalence is demonstrated. In addition, automated applications using model probe substrates and inhibitors to assess the cholestatic potential of drugs and evaluate hepatic drug transport are examined. The successful automation of this technology provides a more reproducible and less labor-intensive approach, reducing potential operator error in complex studies and facilitating technology transfer. (Journal of Biomolecular Screening. 2011;16:427-435)

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Synthesis and Hepatic Transport of Strongly Fluorescent Cholephilic Dipyrrinones.

Cited by 3 publications

References 1 publication

Influence of Conformation and Intramolecular Hydrogen Bonding on the Acyl Glucuronidation and Biliary Excretion of Acetylenic Bis-Dipyrrinones Related to Bilirubin

Influence of Conformation and Intramolecular Hydrogen Bonding on the Acyl Glucuronidation and Biliary Excretion of Acetylenic Bis-Dipyrrinones Related to Bilirubin

Slipping Past UGT1A1 and Multidrug Resistance-Associated Protein 2 in the Liver: Effects of Steric Compression and Hydrogen Bonding on the Hepatobiliary Elimination of Synthetic Bilirubins

Automated Applications of Sandwich-Cultured Hepatocytes in the Evaluation of Hepatic Drug Transport

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