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  • 1
    Electronic Resource
    Electronic Resource
    Microbial and Mammalian Metabolism Studies on the Semisynthetic Antimalarial, Deoxoartemisinin (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1493-1498 
    Details
    ISSN: 1573-904X
    Keywords: antimalarial ; deoxoartemisinin ; microbial ; metabolites ; mammalian ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Deoxoartemisinin is a semisynthetic antimalarial with potential for treatment of multiple drug resistant malaria. Metabolism studies were conducted to aid in future drug development. Methods. Microbial model systems were employed which have been shown to be good predictors of mammalian drug metabolites. Metabolism studies using rats were also performed. Results. Three microbial metabolites of deoxoartemisinin were identified (2, 3, and 4). Metabolite 3 was also found in rat plasma. HPLC/MS analyses were performed on the rat plasma using 2, 3, and 4 as standards. All metabolites were thoroughly characterized by 1H and 13C-NMR. An additional rat plasma metabolite was revealed and it was shown not to be 9α-hydroxyartemisinin. Conclusions. Deoxoartemisinin was metabolized to three microbial metabolites. Metabolism by rats showed the presence of two metabolites in the plasma, one of which was the same as the microbial metabolite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016239505506
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  • 2
    Electronic Resource
    Electronic Resource
    Microbial and Mammalian Metabolism Studies of the Semisynthetic Antimalarial, Anhydrodihydroartemisinin (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 990-994 
    Details
    ISSN: 1573-904X
    Keywords: microbial and mammalian metabolism ; antimalarial ; anhydrodihydroartemisinin ; microbial and mammalian metabolites ; two-dimensional nuclear magnetic resonance (2D-NMR) techniques ; thermospray liquid chromatography/mass spectroscopy(LC/MS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Microbial metabolism studies of the semisynthetic antimalarial anhydrodihydroartemisinin (1), have shown that it is metabolized by a number of microorganisms. Large scale fermentation with Streptomyces lavendulaeL-105 and Rhizopogonspecies (ATCC 36060) have resulted in the isolation of four microbial metabolites. These metabolites have been identified as a 14-carbon rearranged product (2), 9β-hydroxyanhydrodihydroartemisinin (3), 1 l-epi-deoxydihydro-artemisinin (4), and 3α-hydroxydeoxyanhydrodihydroartemisinin (5). Microbial metabolites were completely characterized by spectral methods, including 1H-NMR and 13C-NMR spectroscopy. The structure and stereochemistry of metabolite 2 were unequivocally established by X-ray crystallographic analysis. Thermospray mass spectroscopy/high-performance liquid chromatographic analyses of plasma from rats used in mammalian metabolism studies of 1 have shown microbial metabolite 3 to be the major mammalian metabolite. In vitroantimalarial testing has shown metabolite 3 to possess antimalarial activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018979202933
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  • 3
    Electronic Resource
    Electronic Resource
    13C- and 1H-NMR. Assignments for colchicine derivatives (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 50-56 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C-NMR. spectra of a number of colchicine derivatives are given comprising examples of the normal series (4→10), iso series (11→16) and colchicine series (17), which were either reported in the literature or obtained by partial synthesis or degradation reactions. The 13C-NMR. assignments were made by comparisons with known compounds and selective single-frequency offresonance decoupling experiments. Selective proton decoupling experiments have also allowed assignments of the H - C(11) and H - C(12) protons of the iso and colchicine series.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630106
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  • 4
    Electronic Resource
    Electronic Resource
    Structure Determination of Brominated Morphinan-6-ones by 13C-NMR. Spectroscopy: A novel closure of the oxygen bridge using 4-acetoxymorphinan-6-onesDedicated to Professor George H. Büchi on the occasion of his 60th birthday (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1672-1681 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bromination of (-)-4-hydroxy-N-methylmorphinan-6-one (3), prepared from natural morphine, with 1 mol of bromine in acetic acid, afforded the 1-bromo ketone 5. The structure of 5 was assigned by 13C-NMR.spectroscopy, and confirmed by X-ray diffraction analysis of its hydrobromide salt. It is suggested that monobromination of synthetic (±)-2,4-dihydroxy-N-formylmorphinan-6-one (7) takes in principle a similar course, although the 13C-NMR.spectrum of the primary reaction product 9 could not be measured because of insolubility in commonly used solvents. Monobromination of (-)-4-acetoxy-N-formylmorphinan-6-one (12) of the natural series, and of (±)-2,4-diacetoxy-N-formylmorphinan-6-one (8) of the synthetic series, followed by treatment of the monobrominated ketones with potassium carbonate in methanol resulted in closure of the O-bridge, and afforded after acid hydrolysis, the corresponding 4,5-epoxy-morphinan-6-ones (-)-16 and (±)-17 respectively. This variation of the ring closure reaction represents a novel and convenient method to convert 4-hydroxymorphinan-6-ones into their corresponding 4,5-epoxymorphinan-6-ones, without involving aromatic bromination and with only 1 mol of bromine.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640545
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  • 5
    Electronic Resource
    Electronic Resource
    Revision of the Structure of ‘Epoxycolchicine’ (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 406-412 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Revision der Struktur von «Epoxycolchicin»Die für natürliches «Epoxycolchicin» vorgeschlagene Struktur 2 muss aufgrund einer Kristall-Röntgenstrukturanalyse zu derjenigen des cyclischen Acetals 3 abgeändert werden. Es wird vorgeschlagen, den Namen «Epoxycolchicin» aus der Literatur zu streichen, da er irreführend ist.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630211
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  • 6
    Electronic Resource
    Electronic Resource
    Thermospray mass spectroscopy/high performance liquid chromatographic identification of the metabolites formed from arteether using a rat liver microsome preparation (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 337-351 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermospray LC/MS methods with internal standardization were developed for the quantification of the antimalarial arteether and six of its metabolites at the 1-10 μg/ml level in liver microsome preparations without the use of solvent extraction. The thermospray mass spectra of arteether and most of its metabolites exhibited strong [M + NH4]+ and [M - OR]+ peaks arising from the molecular ion adduct and the loss of the alkoxy or hydroxy group of the side chain. In addition to the six metabolites for which authentic reference standards were available, three additional metabolites were detected. The major metabolites of arteether were found to be dihydroartemisinin, deoxydihydroartemisinin, 3-hydroxydeoxydihydroartemisinin, two isomers of hydroxyarteether, and 3-hydroxydeoxyarteether. Deoxyartheether was not found at significant concentrations in the microsome preparation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180509
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  • 7
    Electronic Resource
    Electronic Resource
    Microbial Metabolism Studies of the Antimalarial Drug Arteether (1990)
    Springer
    Pharmaceutical research 7 (1990), S. 199-203 
    Details
    ISSN: 1573-904X
    Keywords: microbial metabolism ; antimalarial ; arteether ; microbial metabolites ; two-dimensional nuclear magnetic resonance (2D-NMR) techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Microbial metabolism studies of the antimalarial drug arteether (1) have shown that arteether is metabolized by a number of microorganisms. Large-scale fermentation with Aspergillus niger (ATCC 10549) and Nocardia corallina (ATCC 19070) have resulted in the isolation of four microbial metabolites which have been characterized using two-dimensional nuclear magnetic resonance (2D-NMR) techniques. These metabolites have been identified as “AEM1” (2), 3α-hydroxydeoxyarteether (3), 3α-hydroxydeoxydihydroartemisinin (4), and deoxydihydroartemisinin (5).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015845306124
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  • 8
    Electronic Resource
    Electronic Resource
    Structure Elucidation and Thermospray High-Performance Liquid Chromatography/Mass Spectroscopy (HPLC/MS) of the Microbial and Mammalian Metabolites of the Antimalarial Arteether (1990)
    Springer
    Pharmaceutical research 7 (1990), S. 923-927 
    Details
    ISSN: 1573-904X
    Keywords: microbial and mammalian metabolism ; antimalarial ; arteether ; two-dimensional nuclear magnetic resonance (2D-NMR) techniques ; thermospray liquid chromatography/mass spectros-copy (LC/MS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Microbial metabolism studies of the antimalarial drug arteether (1) have shown that arteether is metabolized to six new metabolites in addition to those previously reported (3). Large-scale fermentations with Cunninghamella elegans (ATCC 9245) and Streptomyces lavendulae (L-105) have resulted in the characterization of these metabolites primarily by two-dimensional nuclear magnetic resonance (2D-NMR) methods as 9β-hydroxyarteether (2), a ring rearrangement metabolite (3), 3α-hydroxy-11-epi-deoxydihydroartemisinin (4), 9α-hydroxyarteether (5), 2α-hydroxyarteether (6), and 14-hydroxyarteether (7). Thermospray mass spectroscopy/high-performance liquid chromatographic analyses have shown that four of these metabolites (2, 5, 6, 7) are also present in rat liver microsome preparations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015993722846
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  • 9
    Electronic Resource
    Electronic Resource
    Identification of the in vivo metabolites of the antimalarial arteether by thermospray high-performance liquid chromatography/mass spectrometry (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1991), S. 609-628 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermospray mass spectra of arteether and 16 of its potential metabolites all showed strong [M + NH4]+ ions and with only a few exceptions these compounds also showed spectral peaks corresponding to [M + NH4 - HOR]+ and [M + H - HOR]+, where OR represents the alkoxy or hydroxy group at the 12-position. A method for quantifying the metabolites was developed in which the plasma was spiked with an internal standard (the propyl ether analog of arteether), extracted using a C-18 solid-phase cartridge, then subjected to thermospray high-performance liquid chromatographic/mass spectrometric analysis using selected ion monitoring and a C-18 reversed-phase analytical column. Following the intravenous administration of arteether (11.6 mg kg-1), the plasma was found to contain 12 metabolites of arteether in the 10-1000 ng ml-1 range 15 min post-injection, and within 60 min two of these metabolites attained higher concentrations than that of the parent compound, while several other of the metabolites attained concentrations similar to the parent compound. The pseudo-first-order half-life of arteether was found to be 10.0 ± 0.6 min, while the apparent half-lives of most of the metabolites were in the 15-30 min range. Nine of these metabolites were identified by comparison to authentic reference standards and the structures of three remaining metabolites were tentatively assigned from their spectral and chromatographic properties. The metabolic pathways leading to these 12 metabolites was a rather complex, multiple-step process, but most of the metabolites arose from an enzymatic oxidation at one of three sites; 3α, 9α, or the CH2 of the side-chain. Conversion of the endoperoxide group to an cyclic ether was not a major pathway. The in vitro antimalarial activity of reference standards of several of the metabolites was determined and all of those tested were found to be active in the low nanogram per milliliter range.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200201006
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