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Affiliation(s)
- R. Bakhtiar
- a Novartis Institute for Biomedical Research , 59 Route 10, East Hanover, NJ, 07936, U.S.A
| | - Luis Ramos
- a Novartis Institute for Biomedical Research , 59 Route 10, East Hanover, NJ, 07936, U.S.A
| | - Francis L. S. Tse
- a Novartis Institute for Biomedical Research , 59 Route 10, East Hanover, NJ, 07936, U.S.A
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Shen Z, Reed JR, Creighton M, Liu DQ, Tang YS, Hora DF, Feeney W, Szewczyk J, Bakhtiar R, Franklin RB, Vincent SH. Identification of novel metabolites of pioglitazone in rat and dog. Xenobiotica 2003; 33:499-509. [PMID: 12746106 DOI: 10.1080/0049825031000085951] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
1. Four new metabolites of pioglitazone were identified by liquid chromatography-mass spectrometry (LC-MS/MS) as being formed by hydroxylation (M-VII and M-VIII), opening of the thiazolidinedione ring (M-X) and by desaturation of the terminal ethyl side chain or tether ethoxy moiety (M-IX), respectively. The structure of one of the hydroxylated metabolites (M-VII) was confirmed by chemical modification using the Jones reaction. 2. Oxidative cleavage of the thiazolidinedione ring is a novel pathway not previously reported for pioglitazone. 3. The hydroxylated M-VII was detected in incubations with rat, dog and human liver and kidney microsomes, and in plasma from rats and dogs dosed orally with [(3)H]pioglitazone. 4. The carboxylic acid derivative of M-VII (M-V) and its taurine conjugate were the major radioactive components in dog bile.
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Affiliation(s)
- Z Shen
- Departments of Drug Metabolism, Merck Research Laboratories, Rahway, NJ 07065, USA.
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Bakhtiar R, Khemani L, Hayes M, Bedman T, Tse F. Quantification of the anti-leukemia drug STI571 (Gleevec) and its metabolite (CGP 74588) in monkey plasma using a semi-automated solid phase extraction procedure and liquid chromatography-tandem mass spectrometry. J Pharm Biomed Anal 2002; 28:1183-94. [PMID: 12049982 DOI: 10.1016/s0731-7085(02)00080-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signal Transduction Inhibitor 571 (STI571, formerly known as CGP 57148B) or Gleevec received fast track approval by the US Food and Drug Administration (FDA) for treatment of chronic myeloid leukemia (CML). STI571 (Gleevec) is a revolutionary and promising new oral therapy for CML, which functions at the molecular level with high specificity. The dramatic improvement in efficacy compared with existing treatments prompted an equally profound increase in the pace of development of Gleevec. The duration from first dose in man to completion of the New Drug Application (NDA) filing was less than 3 years. In addition, recently, FDA approved Gleevec for the treatment of gastrointestinal stromal tumor (GIST). In order to support all toxicokinetic (TK) studies with sufficient speed to meet various target dates, a semi-automated procedure using solid phase extraction (SPE) was developed and validated. A Packard Multi-Probe I and a SPE step in a 96-well plate format were utilized. A 3M Empore octyl (C(8))-standard density 96-well plate was used for plasma sample extraction. A Sciex API 3000 triple quadrupole mass spectrometer with an atmospheric pressure chemical ionization (APCI) interface operated in positive ion mode was used for detection. Lower limits of quantification of 1.00 and 2.00 ng/ml were attained for STI571 and its metabolite, CGP 74588, respectively. The method proved to be rugged and allowed the simultaneous quantification of STI571 and CGP 74588 in monkey plasma. Herein, assay development, validation, and representative concentration-time profiles obtained from TK studies are presented.
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Affiliation(s)
- R Bakhtiar
- Department of Drug Metabolism and Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA.
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Bakhtiar R, Jacobson DB. Characterization of strongly bound transition-metal-molecular silane cationic complexes in the gas phase. Organometallics 2002. [DOI: 10.1021/om00032a002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bakhtiar R, Holznagel CM, Jacobson DB. Rearrangement of nascent .alpha.-silyl-substituted carbenium ions in the gas phase. 1,2-Hydrogen versus 1,2-methyl versus 1,2-phenyl migration. J Am Chem Soc 2002. [DOI: 10.1021/ja00035a010] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bruce JE, Cheng X, Bakhtiar R, Wu Q, Hofstadler SA, Anderson GA, Smith RD. Trapping, Detection, and Mass Measurement of Individual Ions in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer. J Am Chem Soc 2002. [DOI: 10.1021/ja00096a046] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bakhtiar R, Holznagel CM, Jacobson DB. Generation and characterization of isomeric iron-silylene and iron-silene cationic complexes in the gas phase. J Am Chem Soc 2002. [DOI: 10.1021/ja00054a050] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jacobson DB, Bakhtiar R. Generation, characterization, and properties of iron-silylene and iron-silene cationic complexes in the gas phase. J Am Chem Soc 2002. [DOI: 10.1021/ja00076a046] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bakhtiar R, Holznagel CM, Jacobson DB. Unimolecular dissociation of methylsilylium and monochloromethylsilylium in the gas phase. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100151a014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bakhtiar R, Holznagel CM, Jacobson DB. Efficient isomerization of Si(C2H5)H2+ to Si(CH3)2H+ by collisional activation in the gas phase. Organometallics 2002. [DOI: 10.1021/om00027a010] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bakhtiar R, Drader JJ, Jacobson DB. Iron-mediated [4 + 2] cycloaddition of 1,3-butadiene with ethyne and propyne in the gas phase. J Am Chem Soc 2002. [DOI: 10.1021/ja00047a060] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bakhtiar R, Lohne J, Ramos L, Khemani L, Hayes M, Tse F. High-throughput quantification of the anti-leukemia drug STI571 (Gleevec) and its main metabolite (CGP 74588) in human plasma using liquid chromatography-tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2002; 768:325-40. [PMID: 11888061 DOI: 10.1016/s1570-0232(01)00611-0] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The signal transduction inhibitor STI571 (formerly known as CGP 57148B) or Gleevec received fast track approval by the US Food and Drug Administration (FDA) for treatment of chronic myeloid leukemia (CML). STI571 is a revolutionary and promising new oral therapy for CML, which functions at the molecular level with high specificity. The dramatic improvement in efficacy compared to existing treatments prompted an equally profound increase in the pace of development of Gleevec. The duration from first dose in man to completion of the New Drug Application (NDA) filing was approximately 2.6 years. In order to support all pharmacokinetics studies with sufficient speed to meet various target dates, a semi-automated procedure using protein precipitation was developed and validated. A Tomtec Quadra 96 (Model 320) and a protein precipitation step in a 96-well plate format were utilized. A Sciex API 3000 triple quadrupole mass spectrometer with an atmospheric pressure chemical ionization interface operated in positive ion mode was used for detection. The method proved to be rugged and allowed the simultaneous quantification of STI571 and its main metabolite (CGP 74588) in human plasma. Herein, assay development, validation, and representative concentration-time profiles obtained from clinical studies are presented.
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Affiliation(s)
- R Bakhtiar
- Department of Drug Metabolism and Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA.
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Bakhtiar R, Nelson RW. Mass spectrometry of the proteome. Mol Pharmacol 2001; 60:405-15. [PMID: 11502869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Affiliation(s)
- R Bakhtiar
- Novartis Institute for Biomedical Research, East Hanover, New Jersey, USA.
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Abstract
Peptidyl-prolyl isomerases (PPIases) are ubiquitous cellular enzymes that play roles in cellular signaling and protein folding. In addition, these proteins are the receptors for the widely used immunosuppressants cyclosporin A and FK506. We report the first structure-activity studies of de novo designed inhibitors of cyclophilin, the cellular target of cyclosporin A. Our mechanism-based inhibitors were modeled on the ground- and transition-state structures of proline-containing peptides, the natural substrates of the enzyme. Both ground-state analogues 1 and transition-state analogues 2 were prepared as single enantiomers from L-proline following a "self-reproduction of chirality" procedure. The binding affinities of the analogues for the active site of cyclophilin were measured by a fluorescence perturbation assay. While the transition-state analogues 2 did not display significant avidity for the active site (K(d) = 77 microM for 2b), several ground-state analogues bound to the enzyme with low micromolar affinity (K(d) = 1.5 microM for 1e). These results proclaim that properly designed small molecular weight molecules can form strong complexes with cyclophilin and may find use as probes in cell biology and as therapeutic agents.
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Affiliation(s)
- H C Wang
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, USA
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Abstract
Recent advances in mass spectrometry have rendered it an attractive and versatile tool in industrial and academic research laboratories. As a part of this rapid growth, a considerable body of literature has been devoted to the application of mass spectrometry in studies involving enantioselectivity, molecular recognition, and supramolecular chemistry. In concert with separation techniques such as capillary electrophoresis and liquid chromatography, mass spectrometry allows rapid characterization of a large array of molecules in complex mixtures. A majority of these findings have been made possible by the introduction of 'soft-ionization' techniques such as electrospray ionization interface. Other techniques such as atmospheric pressure chemical ionization mass spectrometry have been widely used as a rugged interface for quantitative liquid chromatography-mass spectrometry. Herein, we present a brief overview of the above techniques accompanied with several examples of enantioselective capillary electrophoresis- and liquid chromatography-mass spectrometry in drug discovery and development. Although the emphasis of this article is on quantitative enantiomeric chromatography-mass spectrometry, we envisage that similar strategies are adaptable in qualitative studies.
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Affiliation(s)
- R Bakhtiar
- Department of Drug Metabolism and Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, New Jersey, USA.
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He H, Kramp R, Ramos L, Bakhtiar R. A preliminary study on the feasibility of an automated blood-sampling system in conjunction with liquid chromatography/mass spectrometry. Rapid Commun Mass Spectrom 2001; 15:1768-1772. [PMID: 11555879 DOI: 10.1002/rcm.418] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Abstract
Biological polymers undergo numerous significant and fascinating interactions, such as post-translational modifications, non-covalent associations and conformational changes. A valuable parameter for the characterization of a biopolymer is molecular weight. Modern methods of mass spectrometry, including electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry, are ideally suited for the accurate determination of the molecular weight of a biopolymer of interest. Molecular weight measurements are now routinely utilized in the qualitative and quantitative analysis of macromolecules. In many cases small sample quantities (i.e. a few micrograms) limit the utility of nuclear magnetic resonance spectroscopy and X-ray crystallography in obtaining structural information. Thus, mass spectrometry offers an attractive alternative to the more traditional bioanalytical methods for rapid and sensitive measurements. The ultimate goal of these experiments is to obtain sufficient information in order to map the complex molecular circuitry which operates within the cell. In the analysis of complex mixtures mass spectrometry is even more powerful when utilized in conjunction with separation methods. Herein we present some of the aspects of modern biological mass spectrometry for the investigation of large molecules. For more advanced or detailed technical descriptions we refer the reader to a number of recently published reports.
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Affiliation(s)
- R Bakhtiar
- Department of Drug Metabolism and Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA.
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Xu H, Lee E, Sadik OA, Bakhtiar R, Drader J, Hendrikson C. A Receptor-Based Bioassay for Quantitative Detection of Gallium. Anal Chem 2000. [DOI: 10.1021/ac001701h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bakhtiar R, Nelson RW. Electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry. Emerging technologies in biomedical sciences. Biochem Pharmacol 2000; 59:891-905. [PMID: 10692554 DOI: 10.1016/s0006-2952(99)00317-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tremendous progress in biomedical sciences has been made possible in part by recent advances in bioanalytical methods, in particular biological mass spectrometry. Since the introduction of electrospray ionization mass spectrometry (ESI-MS) in 1984 and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) in 1988, the field of bioanalytical mass spectrometry has seen rapid growth. In concert with separation techniques such as capillary electrophoresis and high performance liquid chromatography, mass spectrometry allows characterization of a large array of small organic molecules, peptides, proteins, oligonucleotides, and RNA fragments. Thus, substantially more expedient and definitive determination of molecular weight is now possible by mass spectrometric analysis. In this commentary, general descriptions of ESI- and MALDI-MS are presented. Furthermore, several recent developments and applications in addressing difficult biological problems are discussed.
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Affiliation(s)
- R Bakhtiar
- Department of Chemistry, Stevens Institute of Technology, Hoboken, NJ, USA.
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Abstract
Mass spectrometry is a valuable tool in structural and functional viral proteomics, where it has been used to identify viral capsid proteins, viral mutants, and posttranslational modifications. Further, mass-based approaches combined with time-resolved proteolysis (mass mapping) have revealed the dynamic nature of viral particles in solution; this method is contributing to an understanding of the dynamic domains of the viral capsid which may have significant value in developing new approaches for viral inactivation. As a result of these experiments, and by comparison with complementary data from X-ray crystallography, a new dimension to viral protein structure and function is emerging.
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Affiliation(s)
- J J Thomas
- Beckman Center for Chemical Sciences, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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Brignol N, Bakhtiar R, Dou L, Majumdar T, Tse FL. Quantitative analysis of terbinafine (Lamisil) in human and minipig plasma by liquid chromatography tandem mass spectrometry. Rapid Commun Mass Spectrom 2000; 14:141-149. [PMID: 10637419 DOI: 10.1002/(sici)1097-0231(20000215)14:3<141::aid-rcm856>3.0.co;2-i] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A method using liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the determination of terbinafine in human and minipig plasma has been developed and validated. The method used positive-ion mode for monitoring terbinafine, and used a stable isotope labelled terbinafine as the internal standard. Subsequent to acetonitrile protein precipitation, the supernatant was directly (unfiltered) injected onto the LC column (retention time approximately 4.3 min) for analysis. Interday and intraday accuracy and precision were assessed from the relative recoveries (observed concentration in percent of the nominal value) of spiked samples analyzed on three different days. The lower limit of quantitation (LLOQ) was 0.0679 ng/mL in human and minipig using a plasma sample volume of 0.08 mL. The method was fast, specific, and exhibited ruggedness. Furthermore, the use of turbulent flow chromatography (TurboFlow LC/MS/MS) coupled to mass spectrometry for direct analysis of terbinafine in plasma is discussed. The technique allowed direct introduction of plasma with satisfactory chromatographic peak shape and increased throughput.
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Affiliation(s)
- N Brignol
- Department of Drug Metabolism & Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA
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Majumdar TK, Bakhtiar R, Melamed D, Tse FL. Determination of terbinafine (Lamisil) in human hair by microbore liquid chromatography/tandem mass spectrometry. Rapid Commun Mass Spectrom 2000; 14:1214-1219. [PMID: 10918370 DOI: 10.1002/1097-0231(20000730)14:14<1214::aid-rcm12>3.0.co;2-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
An analytical method for the determination of terbinafine (Lamisil(R)) in human hair was developed and validated. Human hair (10 mg) was hydrolyzed in 0.50 mL of 5.0 N sodium hydroxide for 1.5 h. The aqueous layer was extracted with 1.5 mL of n-hexane. The organic layer was separated and re-extracted with 0.20 mL of formic acid (12.5%)/2-propanol (85:15, v/v). The aqueous layer was separated and 0.010 mL of the aqueous extract was injected onto a reversed-phase microbore (50 x 1.0 mm i.d.) column for analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS). The instrument was equipped with an electrospray ionization (ESI) interface and operated in the positive ion mode of detection. Interday and intraday accuracy and precision were assessed from the relative recoveries of spiked samples analyzed on three different days. The method showed excellent specificity and ruggedness with a lower limit of quantitation of 10 ng/g (i.e., 10 ppb) using 10 mg of human hair.
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Affiliation(s)
- T K Majumdar
- Department of Drug Metabolism & Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA.
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Bakhtiar R. In vitro exposure of human hemoglobin to the antineoplastic drug thiotepa. Rapid Commun Mass Spectrom 2000; 14:534-537. [PMID: 10717668 DOI: 10.1002/(sici)1097-0231(20000331)14:6<534::aid-rcm894>3.0.co;2-p] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Abstract
Chiral liquid chromatography is a well-established area of bioanalytical chemistry and is often used during the processes of drug discovery and development. The development and use of a chiral drug require the understanding of the pharmacokinetic characteristics of each of the enantiomers, including potential differences in their absorption, distribution, metabolism, and excretion. Chromatographic techniques coupled to atmospheric pressure ionization-tandem mass spectrometry have shown potential as sensitive and robust tools in the quantitative and qualitative determination of enantiomers in biologic fluids and tissue extracts. However, development of a chiral liquid chromatography method requires time-consuming procedures that are devised empirically. Clearly, there is an incentive to design chromatographic approaches that are easy to use, compatible with mass spectrometry ionization interface conditions, exhibit relatively short run times without compromising sensitivity, and offer a broad analyte specificity. For these reasons, the present paper explores the feasibility of the bonded macrocyclic glycopeptide phases (teicoplanin and vancomycin) for analysis by chiral liquid chromatography/tandem mass spectrometry. Ritalinic acid, pindolol, fluoxetine, oxazepam, propranolol, terbutaline, metoprolol, and nicardipine were tested in this study. Furthermore, an example of a simultaneous chiral LC/MS/MS detection (chromatographic run time approximately 10 min) of four pharmaceutical products resulting in baseline resolutions of all four pairs of enantiomers is presented. Methanol, an MS-compatible mobile phase, was utilized in all the experiments.
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Affiliation(s)
- R Bakhtiar
- Department of Drug Metabolism and Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA.
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Majumdar TK, Bakhtiar R, Melamed D, Tse FL. Trace-level quantitation of iralukast in human plasma by microbore liquid chromatography/tandem mass spectrometry. Rapid Commun Mass Spectrom 2000; 14:476-481. [PMID: 10717659 DOI: 10.1002/(sici)1097-0231(20000331)14:6<476::aid-rcm898>3.0.co;2-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Iralukast (CGP 45715A) is a potent peptido-leukotriene antagonist that is active in various in vitro and animal models for the treatment of asthma. An analytical challenge was to develop a sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method with a lower limit of quantitation (LLOQ) of 10 pg/mL for the analysis of iralukast when administered at low doses during clinical trials. Several issues had to be addressed in order to devise a LC/MS/MS assay for the above compound. First, iralukast appeared to be light sensitive and unstable at room temperature under acidic conditions. Second, a LLOQ of 10 pg/mL was needed to support several clinical trials. Third, positive electrospray ionization of iralukast did not yield the necessary sensitivity required for studies in humans. Consequently, LC/MS/MS conditions were optimized for the negative ion mode of detection. Fourth, sample preparation steps proved to be critical to reduce the possibility of microbore HPLC column (50 mm x 1.0 mm i.d.) obstruction, chromatographic deterioration, and matrix-mediated electrospray ion suppression. While our validated method addressed the above challenges, its major drawback was limited sample throughput capability. Nonetheless, plasma concentration-time profiles for patients with moderate asthma after oral administration of 200, 500, 1000, and 5000 microgram/kg/day of iralukast were successfully obtained.
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Affiliation(s)
- T K Majumdar
- Department of Drug Metabolism & Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA.
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Ramos L, Brignol N, Bakhtiar R, Ray T, Mc Mahon LM, Tse FL. High-throughput approaches to the quantitative analysis of ketoconazole, a potent inhibitor of cytochrome P450 3A4, in human plasma. Rapid Commun Mass Spectrom 2000; 14:2282-2293. [PMID: 11114039 DOI: 10.1002/1097-0231(20001215)14:23<2282::aid-rcm164>3.0.co;2-v] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ketoconazole, an imidazole-piperazine compound, is an orally active antimycotic agent. In addition, ketoconazole is a specific inhibitor of cytochrome P450 3A4. As about 60% of oxidized drugs are biotransformed by this isoform, the potential effect of a concomitant administration of ketoconazole on drug disposition may be of interest during drug development. The present paper describes three different approaches (methods A, B, and C) to attain high-throughput sample preparation and analysis in the quantification of ketoconazole in human plasma. Method A consisted of acetonitrile precipitation in a 96-well plate, transfer of the supernatant via a Tomtec Quadra 96 Model 320, and subsequent injection onto a 50 x 4.6 mm (i.d.) Develosil Combi-RP-5 column (packed with C30 bonded silica particles). Method B consisted of an identical sample preparation to method A with the exception that a Michrom Magic Bullet(trade mark) column, 2.0 --> 0.50 mm (i.d., tapered bore) x25 mm length, was used. Lastly, in method C, a turbulent-flow chromatography (TurboFlow LC/APCI-MS/MS) module was used for the direct analysis of ketoconazole in human plasma. A Sciex API 3000 was used in methods A and B, while a Micromass Quattro LC was employed in method C. Based on the values obtained for the calibrator (standard) and quality control samples, all three protocols yielded satisfactory accuracy, precision, and reduced manual sample preparation time.
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Affiliation(s)
- L Ramos
- Department of Drug Metabolism & Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA
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Ramos L, Bakhtiar R, Tse FL. Liquid-liquid extraction using 96-well plate format in conjunction with liquid chromatography/tandem mass spectrometry for quantitative determination of methylphenidate (Ritalin) in human plasma. Rapid Commun Mass Spectrom 2000; 14:740-745. [PMID: 10825011 DOI: 10.1002/(sici)1097-0231(20000515)14:9<740::aid-rcm938>3.0.co;2-c] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Methylphenidate (MPH; Ritalin: methyl-alpha-phenyl-2-piperidinacetate hydrochloride) is utilized for the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy. Recently, we described a rapid enantioselective liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the determination of the enantiomers of MPH (Rapid Commun. Mass Spectrom. 1999; 13: 2054). A lower limit of quantification (LLOQ) of 87 pg/mL was attained for the human plasma assay. The present paper describes a high-throughput sample preparation procedure in conjunction with racemic LC/MS/MS analysis for MPH with a LLOQ of 50 pg/mL. A semi-automated robotics method using liquid-liquid extraction (LLE) in a 96-well plate format was developed and validated. The correlation coefficients were > or =0.998 for MPH indicating good fits of the regression models over the range of the calibration curve. The accuracy and precision of the semi-automated approach were comparable to those obtained using the manual sample preparation technique reported previously (vide supra). The current method can easily be adapted to the enantioselective LC/MS/MS assay of MPH. The assay was simple, fast, specific, and exhibited excellent ruggedness.
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Affiliation(s)
- L Ramos
- Drug Metabolism and Pharmacokinetics Department, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA
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Abstract
The detection of gallium in biological samples is required due to its role in the diagnosis of tumor and for possible treatment of malignancies. However, the use of purely instrumental techniques is unsuitable for detection of low levels of gallium in biological matrixes. We have synthesized new protein conjugates based on 4-(2-pyridylazo) ligands. The conjugates were successfully employed for the detection of gallium in biological matrixes using a nonantibody-based sandwich assay format. The recovery level obtained was between 97 and 101.3 with a relative standard deviation of less than 5%. The assay resulted in a detection limit of 5 x 10(-8) M and a remarkable selectivity for gallium(III) relative to other metals investigated. The new method provided adequate accuracy for gallium applicable for animal physiology and clinical toxicology.
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Affiliation(s)
- H Xu
- Department of Chemistry, State University of New York at Binghamton 13902, USA
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30
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Abstract
Inorganic complexes have long been utilized for many therapeutic purposes. They were used or tried, perhaps because of the general notion that inorganic compounds (e.g., metal complexes) are toxic and a controlled use of such a compound may suppress some biological process. In this review, we briefly outline the properties of several selected groups of inorganic complexes and how they can affect biological systems and contribute to human pathologies.
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Affiliation(s)
- R Bakhtiar
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030, USA
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Ramos L, Bakhtiar R, Tse F. Application of liquid chromatography atmospheric pressure chemical ionization tandem mass spectrometry in the quantitative analysis of glyburide (glibenclamide) in human plasma. Rapid Commun Mass Spectrom 1999; 13:2439-2443. [PMID: 10589091 DOI: 10.1002/(sici)1097-0231(19991230)13:24<2439::aid-rcm809>3.0.co;2-c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Glyburide (glibenclamide) is widely prescribed in the treatment of Type II diabetes. A validated liquid chromatography atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI-MS/MS) method for the determination of glyburide is reported. The method uses a stable isotope labeled glyburide as the internal standard. Subsequent to acetonitrile protein precipitation, the supernatant was directly (unfiltered) injected onto the LC column (retention time approximately 3 min) for analysis. A lower limit of quantification (LLOQ) of 1.01 ng/mL was attained for the human plasma assay. The method was fast, specific, and exhibited excellent ruggedness. It was successfully applied to the analysis of clinical samples from patients dosed with glyburide.
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Affiliation(s)
- L Ramos
- Bioanalytics and Pharmacokinetics, Novartis Institute for Biomedical Research, East Hanover, NJ 07936, USA
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32
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Ramos L, Bakhtiar R, Majumdar T, Hayes M, Tse F. Liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry enantiomeric separation of dl-threo-methylphenidate, (Ritalin) using a macrocyclic antibiotic as the chiral selector. Rapid Commun Mass Spectrom 1999; 13:2054-2062. [PMID: 10510420 DOI: 10.1002/(sici)1097-0231(19991030)13:20<2054::aid-rcm749>3.0.co;2-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Vancomycin, a macrocyclic antibiotic, is an amphoteric glycopeptide produced by Streptomyces orientalis which has proven to be a viable chiral selector for high performance liquid chromatograph (HPLC) (D. W. Armstrong, Y. Tang, S. Chen, Y. Zhou, C. Bagwill and J-R. Chen, Anal. Chem. (1994; 66: 1473). While it is related to other glycopeptide antibiotics, vancomycin has a number of unique structural features, including 18 stereogenic centers, five aromatic rings, and two side chains one of which is a carbohydrate dimer. Therefore, a vancomycin-based stationary phase appears to be multimodal in that it can be utilized in both normal-phase and reversed-phase liquid chromatography. Consequently, the enantiomeric separation may be operative via several mechanisms, including pi-pi complexation, dipole stacking, inclusion, hydrogen bonding, or combinations of these interactions. LC/MS/MS is a powerful tool for quantitative analysis when evaluated on the basis of speed, specificity, reliability and sensitivity. For these reasons, the present paper explored the feasibility of bonded macrocyclic glycopeptide phases for chiral LC/MS/MS quantitative analysis. Methylphenidate was used as a model compound. A rapid chiral bioanalytical method (<7.5 min) for the determination of the enantiomers of methylphenidate was developed. A lower limit of quantification (LLOQ) of 87 pg/mL was attained for the human plasma assay. This is to our knowledge the first example of enantioselective reversed-phase LC/MS/MS for methylphenidate. The chiral column was relatively cost effective and exhibited excellent performance with no separation deterioration observed after approximately 2500 injections.
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Affiliation(s)
- L Ramos
- Drug Metabolism and Pharmacokinetics Department, Novartis Institute for Biomedical Research, East Hanover, New Jersey 07936, USA
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33
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Zhu L, Bakhtiar R, Kostić NM. Transition-metal complexes as alternatives to proteolytic enzymes. Regioselective cleavage of myoglobin by palladium(II) aqua complexes. J Biol Inorg Chem 1998. [DOI: 10.1007/s007750050248] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Walker RB, Dholakia VN, Brasfield KL, Bakhtiar R. Effect of hydroxypropyl-beta-cyclodextrin on the central stimulant activity of (-)-ephedrine and an oxazolidine prodrug in rats. Gen Pharmacol 1998; 30:725-31. [PMID: 9559325 DOI: 10.1016/s0306-3623(97)00341-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
1. Hydroxypropyl-beta-cyclodextrin (HP-beta-CD) increases the stability of the oxazolidine prodrug toward hydrolysis. 2. The binding constant (Kb) and rate constant (Kc) for the hydrolysis of the prodrug-HP-beta-CD complex were calculated from the kinetic data. 3. Ion-spray mass spectra confirmed prodrug-HP-beta-CD complexation. 4. Mass spectral and kinetic data indicated 1:1 stoichiometry for the complex. 5. A significant elevation of locomotor activity in rats was observed when either (-)-ephedrine or the prodrug was administered by either the intraperitoneal or the oral route. 6. Addition of HP-beta-CD potentiated the central nervous system effect of both (-)-ephedrine and the prodrug when administered intraperitoneally. However, when the drugs were administered orally, HP-beta-CD caused a decrease in activity.
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Affiliation(s)
- R B Walker
- Department of Chemistry and Physics, University of Arkansas at Pine Bluff 71611, USA.
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35
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36
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Abstract
Depsipeptide, a cyclic peptide (FR), isolated from Chrombacterium violaceum strain WB968 by Fujisawa Company during a screening program for anti-oncogene agents, possesses potent antitumor activity against human tumor cell lines and xenografts. This compound has been selected for preclinical and early clinical development by the National Cancer Institute. The pharmacokinetics and oral bioavailability of this depsipeptide in the rat were investigated in the present study. A sensitive and specific electrospray LC-tandem mass spectrometry method was first developed and validated for the analysis of this depsipeptide in plasma using t-boc-alpha-d-glutamic acid benzyl ester as the internal standard. The routine sensitivity limit was 1 or 10 ng/ml using 1.0 or 0.1 ml of plasma sample. The within-run CV values were 11.8, 17.9, 11.0, and 5.0% at 1, 10, 100, and 500 ng/ml levels, respectively, with corresponding accuracy of 94.4, 109, 95, and 97% (all n = 6). A formulation based on ethanol, normal saline and PEG400 was then developed and Fischer rats were given this formulated drug separately by intravenous and oral route. Plasma drug concentrations were measured by this method and pharmacokinetics were analyzed by the standard techniques. Plasma concentration-time profiles were found to follow a biexponential decline with a mean terminal t1/2 of 97 min and mean total clearance (CLt) of 425.3 ml/min/kg following i.v. dosing at 10 mg/kg. Following oral dosing at 50 mg/kg, the peptide was absorbed but produced erratic drug levels also with a bioavailability of 15.6%. Thus, active plasma concentrations can be produced up to 3 hrs in the rat following a single dose at 10 mg/kg and the peptide represents one of the very few orally absorbed peptides reported.
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Affiliation(s)
- K K Chan
- College of Pharmacy, Ohio State University, Columbus, USA
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37
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Bakhtiar R, Leung KH, Stearns RA, Hop CE. Evidence for a novel heme adduct generated by the in vitro reaction of 2,4,6-trinitrotoluene with human hemoglobin using electrospray ionization mass spectrometry. J Inorg Biochem 1997; 68:273-8. [PMID: 9397575 DOI: 10.1016/s0162-0134(97)00108-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The bioactivation of nitroaromatic compounds to highly reactive intermediates is responsible for the genotoxic and cytotoxic effects by reaction with DNA and proteins. Due to its continued use as a secondary explosive and its prevalence at contaminated sites, the mechanism of covalent binding of 2,4,6-trinitrotoluene (TNT), or its metabolites, to critical cellular proteins has been of interest. Herein, we report the in vitro reaction of TNT with human hemoglobin under anaerobic and reductive (using sodium hydrosulfite) conditions, yielding a novel adduct between a putative nitrosodinitrotoluene (MW = 211 Da) and the prosthetic heme group (iron protoporphyrin-IX or heme b). While the covalent modification of hemoglobin polypeptide chains by TNT has been established, to our knowledge, this is the first example of a heme-TNT related adduct. This finding could be of relevance in investigation of biotransformation of TNT in subjects exposed to TNT via skin exposure or inhalation.
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Affiliation(s)
- R Bakhtiar
- Department of Drug Metabolism, Merck Research Laboratories, Rahway, New Jersey, USA.
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38
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Bakhtiar R, Leung KH. Covalent binding of 2,4,6-trinitrotoluene to human hemoglobin. Evidence for protein adducts probed by electrospray ionization mass spectrometry. Rapid Commun Mass Spectrom 1997; 11:1935-1937. [PMID: 9404041 DOI: 10.1002/(sici)1097-0231(199711)11:17<1935::aid-rcm98>3.0.co;2-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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39
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Bakhtiar R, Hop CE. A study of the complexation between dimethyl-beta-cyclodextrin and steroid hormones using electrospray ionization mass spectrometry. Rapid Commun Mass Spectrom 1997; 11:1478-1481. [PMID: 9299764 DOI: 10.1002/(sici)1097-0231(19970830)11:13<1478::aid-rcm30>3.0.co;2-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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40
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Bakhtiar R, Hop CE, Walker RB. Effect of cyclodextrins on the hydrolysis of an oxazolidine prodrug of (1R,2S)-(-)-ephedrine-cis-2-(4-methoxyphenyl)-3, 4-dimethyl-5-phenyloxazolidine. Rapid Commun Mass Spectrom 1997; 11:598-602. [PMID: 9149432 DOI: 10.1002/(sici)1097-0231(199704)11:6<598::aid-rcm903>3.0.co;2-v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Molecular complexes of an oxazolidine prodrug of (-)-ephedrine, cis-2-(4-methoxyphenyl)-3,4-dimethyl-5-phenyloxazolidine, with alpha-, beta-, dimethyl-beta- (DM-beta-) and hydroxypropl-beta- (HP-beta-) cyclodextrins (CDs) were examined using ionspray mass spectrometry. The results suggest, under our experimental conditions, a 1:1 stoichiometric complex between the prodrug and all CDs. Apart from the putative inclusion complexation, the stabilization effect of CDs on the prodrug in an aqueous solution was studied. beta-, DM-beta- and HP-beta-CD exhibited a retardation effect on the rate of hydrolysis of the prodrug. Conversely, alpha-CD did not alter the rate of hydrolysis even at excess concentrations. Presumably, the larger cavity diameter of beta-CDs may permit a greater depth of penetration of the prodrug, resulting in its shielding from hydrolysis. The observations in this work indicate that mass spectrometry could be a rapid and informative analytical method to aid in the preliminary evaluation of the potential utility of CDs in enhancement of drug stability.
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Affiliation(s)
- R Bakhtiar
- Merck Research Laboratories, Rahway, NJ 07065-0900, USA
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41
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Bakhtiar R, Jacobson DB. Erratum to: "Transition-metal mediated heteroatom removal by reactions of FeL (+)[L=O, C 4H 6, c-C 5H 6, c-C 5H 5, C 6H 6, C 5H 4 (=CH 2)] with Furan, Thiophene, and Pyrrole in the Gas Phase. J Am Soc Mass Spectrom 1996; 7:1177. [PMID: 24203081 DOI: 10.1016/s1044-0305(96)00144-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- R Bakhtiar
- Department of Chemistry, North Dakota State University, Fargo, North Dakota, USA
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42
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Bakhtiar R, Jacobson DB. Transition-metal mediated heteroatom removal by reactions of FeL(+) [L=O, C 4H 6, c-C 5H 6, c-C 5H 5, C 6H 6, C 5H 4(=CH 2)] with furan, thiophene, and pyrrole in the gas phase. J Am Soc Mass Spectrom 1996; 7:938-952. [PMID: 24203608 DOI: 10.1016/1044-0305(96)00024-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/1996] [Accepted: 04/11/1996] [Indexed: 06/02/2023]
Abstract
Reactions of Fe(+) and FeL(+) [L=O, C4H6, c-C5H6, C5H5, C6H6, C5H4(=CH2)] with thiophene, furan, and pyrrole in the gas phase by using Fourier transform mass spectrometry are described. Fe(+), Fe(C5H5)(+), and FeC6H 6 (+) yield exclusive rapid adduct formation with thiophene, furan, and pyrrole. In addition, the iron-diene complexes [FeC4H 6 (+) and Fe(c-C5H6)(+)], as well as FeC5H4(=CH2)(+) and FeO(+), are quite reactive. The most intriguing reaction is the predominant direct extrusion of CO from furan by FeC4H6 (+), Fe(c-C5H6)(+), and FeC5H4(=CH2)(+). In addition, FeC4H 6 (+) and Fe(c-C5H6)(+) cause minor amounts of HCN extrusion from pyrrole. Mechanisms are presented for these CO and HCN extrusion reactions. The absence of CS elimination from thiophene may be due to the higher energy requirements than those for CO extrusion from furan or HCN extrusion from pyrrole. The dominant reaction channel for reaction of Fe(c-C5H6)(+) with pyrrole and thiophene is hydrogen-atom displacement, which implies D(O)(Fa(N5H5)(+)-C4H4X)>D(O)(Fe(C5H5)(+)-H)=46±5 kcal mol(-1). D(O)(Fe(+)-C4H4S) and D(O)(Fe(+)-C4H5N)=D(O)(Fe(+)-C4H6)=48±5 kcal mol(-1). Finally, 55±5 kcal mol(-1)=D(O)(Fe(+)-C6H6)>D(O)(Fe(+)-C4H4O)>D(O)(Fe(+)-C2H4)=39.9±1.4 kcal mol(-1). FeO(+) reacts rapidly with thiophene, furan, and pyrrole to yield initial loss of CO followed by additional neutral losses. D(O)(Fe(+)-CS)>D(O)(Fe(+)-C4H4S)≈48±5 kcal mol(-1) and D(O)(Fe(+)-C4H5N)≈48±5 kcal mol(-1)>D(O)(Fe(+)-HCN)>D(O)(Fe(+)-C2H4)=39.9±1.4 kcal mil(-1).
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Affiliation(s)
- R Bakhtiar
- Department of Chemistry, North Dakota State University, Fargo, North Dakota, USA
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43
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Cheng X, Camp DG, Wu Q, Bakhtiar R, Springer DL, Morris BJ, Bruce JE, Anderson GA, Edmonds CG, Smith RD. Molecular weight determination of plasmid DNA using electrospray ionization mass spectrometry. Nucleic Acids Res 1996; 24:2183-9. [PMID: 8668552 PMCID: PMC145889 DOI: 10.1093/nar/24.11.2183] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Ionization and molecular weight (MW) determination of megadalton size plasmid DNA has been achieved using electrospray ionization (ESI) with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. DNA molecules were shown to remain intact through electrospray ionization by collection on a specially prepared surface, followed by agarose gel electrophoresis. Individual highly charged ions of plasmid DNA produced by ESI were trapped in an FTICR cell for up to several hours and reacted with acetic acid to induce charge state shifts. Measurements of mass-to-charge ratios for these multiple peaks arising from charge state shifting give MW measurements of individual ions with an average accuracy of 0.2%. The MW distribution was obtained by measurements for a number of individual ions from the same sample [plasmid DNA: pGEM-5S MW(cal) = 1.946 MDa], yielding a MW(obs) of 1.95 +/- 0.07 MDa for ions clustered in the vicinity of the expected MW.
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Affiliation(s)
- X Cheng
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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44
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Wu Q, Van Orden S, Cheng X, Bakhtiar R, Smith RD. Characterization of cytochrome c variants with high-resolution FTICR mass spectrometry: correlation of fragmentation and structure. Anal Chem 1995; 67:2498-509. [PMID: 8686880 DOI: 10.1021/ac00110a027] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The dissociation of cytochrome c ions (15+ charge state) generated by electrospray ionization has been studied by Fourier transform ion cyclotron resonance mass spectrometry (FTICR) using a sustained off-resonance irradiation/collision-induced dissociation (SORI-CID) technique. Over 95% of the fragment ions can be accurately assigned (to better than 10 ppm), yielding information on the primary sequences of the various proteins. Up to four stages of mass spectrometry (MS4) have been achieved without the need for quadrupole excitation/collisional cooling of the product ions. The subtle structural differences among the cytochrome c variants (from bovine, tuna, rabbit, and horse) are clearly reflected in their fragmentation patterns: replacing 3 out of 104 residues of the cytochrome c is shown to dramatically change the dissociation pattern. Of particular importance are a variety of results indicating that the dissociation of the cytochrome c's is influenced by higher-order structure and charge location, in addition to the primary structure (i.e., sequence). No fragmentation is observed in the region between residues 10-20 and little dissociation between residues 70-90. This is most likely due to the interactions of the heme group with the polypeptide chain, and such a heme "footprinting" pattern is analogous to the protein conformation in solution. These studies demonstrate that electrospray ionization-FTICR using SORI-CID can be a useful tool to probe not only the small differences in the primary sequences of proteins but also suggest the potential for probing their higher-order structures and yielding information not readily available from H/D exchange or circular dichoism studies.
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Affiliation(s)
- Q Wu
- Chemical Sciences Department, Pacific Northwest Laboratory, Richland, Washington 99352, USA
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Bakhtiar R, Stearns RA. Studies on non-covalent associations of immunosuppressive drugs with serum albumin using pneumatically assisted electrospray ionization mass spectrometry. Rapid Commun Mass Spectrom 1995; 9:240-244. [PMID: 7535601 DOI: 10.1002/rcm.1290090313] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Pneumatically assisted electrospray ionization (ion-spray) mass spectrometry was employed in the detection of non-covalent interactions of immunosuppressive drugs with proteins. Non-covalent complexes of albumin (rat and bovine) with FK506, dihydro-FK506, and FK520 were observed. No complexation was detected between albumin and cyclosporin A (CsA), even at a protein-ligand molar ratio of 1:20. It is suggested that the lack of detection of an albumin-CsA non-covalent complex may be attributed to dissociation of the weakly associated species during ion vaporization. Nonetheless, preliminary results indicate that ion-spray mass spectrometry has potential in qualitative evaluation of drug-plasma protein interaction.
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Affiliation(s)
- R Bakhtiar
- Department of Drug Metabolism (I), Merck Research Laboratories, Rahway, New Jersey 07065-0900
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Bakhtiar R, Wu Q, Hofstadler SA, Smith RD. Charge state specific facile gas-phase cleavage of Asp 75-Met 76 peptide bond in the alpha-chain of human apohemoglobin probed by electrospray ionization mass spectrometry. Biol Mass Spectrom 1994; 23:707-10. [PMID: 7811760 DOI: 10.1002/bms.1200231110] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Herein, we present the first example of charge state specific facile gas-phase cleavage of an aspartic acid-methionine peptide linkage. This cleavage (Asp 75-Met 76) was observed in the alpha-chain of human adult hemoglobin (Hb) and was probed by electrospray ionization mass spectrometry. This specific conformational and/or charge density dependent dissociation was observed primarily in the [M + 11H]11+ and [M + 12H]12+ species. A mechanism involving an intramolecular proton transfer from the protonated carboxyl side chain of Asp 75 to the neighboring Met 76 residue yielding an anhydride moiety at the C-terminal of the Asp 75 is proposed. Dramatic differences in dissociation of [M + 13H]13+ and [M + 14H]14+ species were observed.
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Affiliation(s)
- R Bakhtiar
- Chemical Sciences Department, Pacific Northwest Laboratory, Richland, Washington 99352
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Hofstadler SA, Wahl JH, Bakhtiar R, Anderson GA, Bruce JE, Smith RD. Capillary electrophoresis fourier transform ion cyclotron resonance mass spectrometry with sustained off-resonance irradiation for the characterization of protein and peptide mixtures. J Am Soc Mass Spectrom 1994; 5:894-899. [PMID: 24226235 DOI: 10.1016/1044-0305(94)87014-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/1994] [Revised: 06/13/1994] [Accepted: 06/14/1994] [Indexed: 06/02/2023]
Abstract
A new approach to protein and peptide analysis that involves the coupling of on-line capillary electrophoresis-electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry with a variation of sustained off-resonance irradiation is described. With this technique, multiple irradiation frequencies are broadcast simultaneously, which yields fragmentation of species at different mass-to-charge ratio values from the same waveform. In conjunction with capillary electrophoresis, this technique can provide sequence information from small amounts of proteins or peptides in complex mixtures. Initial results obtained from a mixture of gramicidin S (1141 u), bee venom melittin (2845 u), and equine apomyoglobin (16,951 u) are presented.
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Affiliation(s)
- S A Hofstadler
- Chemical Methods and Separations Group, Chemical Sciences Department, Battelle, Pacific Northwest Laboratories, Battelle Boulevard, P8-19, P.O. Box 999, 99352, Richland, WA
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48
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Cheng X, Bakhtiar R, Van Orden S, Smith RD. Charge-state shifting of individual multiply-charged ions of bovine albumin dimer and molecular weight determination using an individual-ion approach. Anal Chem 1994; 66:2084-7. [PMID: 8067525 DOI: 10.1021/ac00085a025] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Ion-molecule reactions of individual multiply-protonated ions of bovine albumin dimer, formed from electrospray ionization, have been studied using a Fourier transform ion cyclotron resonance mass spectrometer. Upon reaction of ammonia with a group of individual ions, charge-state shifting was observed due to proton transfer. Repeated additions of ammonia during remeasurements of the same ion population were observed to induce multiple-step charge-state shifts. Charge-state-dependent reactivity, as well as nonstatistical behavior in reactivity, was observed due to the small ion population. The molecular weights of individual ions whose charge state shifted during reaction were determined with an accuracy of 67 ppm, the first example of using an individual-ion approach to the determination of molecular weight for a large biopolymer. The molecular weight distribution of a group of ions can be determined with a precision related to the number of ions examined and the weight heterogeneity of the sample. We obtained the molecular weight for eight individual ions from which a molecular weight of 133,320 +/- 210 Da was calculated for bovine albumin dimer.
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Affiliation(s)
- X Cheng
- Chemical Sciences Department, Pacific Northwest Laboratory, Richland, Washington 99352
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Bakhtiar R, Holznagel CM, Jacobson DB. Generation and characterization of isomeric iron-silylene and iron-silene cationic complexes in the gas phase. [Erratum to document cited in CA118(17):169276k]. J Am Chem Soc 1993. [DOI: 10.1021/ja00060a087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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