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  • 1
    ISSN: 1573-904X
    Schlagwort(e): adinazolam mesylate ; gradient reversed-phase liquid chromatography ; mass spectrometry ; decomposition products assay
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A gradient high performance liquid chromatographic method was developed to determine degradation products of adinazolam mesylate in a sustained release tablet formulation. Sample preparations were chromatographed on a YMC-Basic column using a formate buffer/acetonitrile gradient with absorbance detection at 254 nm. Adinazolam mesylate was found to degrade at high relative humidity and temperature to form a major product, the 6-aminoquinoline analog, plus numerous other compounds. Five of these compounds were identified and their structures indicate that the solid-state degradation of adinazolam, in the presence of sufficient moisture, involves not only a hydrolytic mechanism, but also an oxidative mechanism. Potential process impurities were resolved from the drug and degradation products. Recovery was near 100% over the 0.5 to 10% range for the major degradate (6-aminoquinoline) and over the 0.5 to 1% range for the other analytes. The method was applied to tablet samples stressed at high relative humidity and temperature. The relative standard deviation of the assay for the 6-aminoquinoline was less than 2% and less than 13% for the minor components. Calculated mass balances (sum of adinazolam plus degradation products in the degraded tablet divided by the same sum in the undegraded tablet) were less than 100% and were dependent on the extent of degradation in the tablet. The average mass balance result obtained for samples that were an average of 9.5% degraded was 95.0 ± 1.5%. It is possible that the decrease in mass balance with increase in percent degradation may be explained by the formation of many components at trace levels due to degradation by various permutations of hydrolytic and oxidative reaction pathways.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1573-904X
    Schlagwort(e): fluphenazine ; stable isotope ; deuterium labeled ; mass spectrometry ; schizophrenics ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    The protein journal 9 (1990), S. 623-632 
    ISSN: 1573-4943
    Schlagwort(e): Pancreatic thread protein ; primary structure ; mass spectrometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Pancreatic thread protein (PTP) forms double helical threads in the neutralpH range after purification, undergoing freely reversible,pH-dependent globule-fibril transformation. The purified bovine PTP consists on SDS gels of two carbohydrate-free polypeptide chains (Grosset al., 1985). Plasma desorption mass spectrometry and amino acid sequence analysis now confirm that bovine PTP contains two disulfide-bonded polypeptides, an A chain of 101 amino acid residues with a molecular weight of 11,073 and a B chain of 35 residues with a molecular weight of 3970. The intact protein exhibits a molecular weight of 15,036, agreeing 〉99.9% with the molecular weight calculated from the sequence. The B chain sequence was determined by gas-phase Edman degradation of the intact polypeptide. The A chain sequence was determined from overlapping peptides generated by cleavage at lysyl, tryptophanyl, and aspartyl-prolyl residues. Based upon the bovine PTP cDNA structure, the two chains of the protein result from cleavage of a single polypeptide with removal of a dipeptide between the NH2-terminal A chain and COOH-terminal B chain. Comparison of bovine PTP with other proteins reveals significant structural relatedness with the single-chain homologues from human and rat pancreas and with the motif associated with Ca2+-dependent carbohydrate recognition domains. The physiological role of PTP has not yet been resolved. The protein is present in very high concentration in pancreatic secretion and it has been detected in brain lesions in Alzheimer's disease and Down syndrome and in regenerating rat pancreatic islets. The present results provide a firm protein base for ongoing molecular, physical-chemical, and structure-function studies of this unusual protein.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1573-1561
    Schlagwort(e): Alkaloids ; mass spectrometry ; infrared spectroscopy ; amphibians ; ants ; decahydroquinolines ; quinolizidines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Three alkaloids—two minor decahydroquinolines (DHQs) and a major quinolizidine—were detected in an extract of a Brazilian myrmicine ant (Solenopsis (Diplorhoptrum) sp. picea group). One DHQ (3) was identical to a known frog-skin alkaloid, cis-195A (cis-5-methyl-2-propyldecahydroquinoline), while the second DHQ, an isomer of 3, designated 195J, was assigned a tentative cis-2-methyl-5-propyldecahydroquinoline structure (2) based on mass and infrared spectra. The third alkaloid proved identical to the frog-skin alkaloid 195C, for which a structure had not been previously proposed. Mass and infrared spectral analysis, including chemical ionization tandem mass spectrometry, indicated a 4-methyl-6-propylquinolizidine structure (1) for 195C. The four possible diastereomers were synthesized and the (6Z,10E)-4-methyl-6-propylquinolizidine diastereomer (1b) was identical to the natural alkaloid. Skin extracts of a population of a Madagascan mantelline frog contained, among other alkaloids, minor amounts of the same alkaloid triad 1–3 with 1 again predominating. The common occurrence of alkaloids 1–3 in both ant and frog supports the hypothesis that ants are a likely dietary source for sequestered frog-skin alkaloids and brings to six, the alkaloid classes common to ant and frog.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1573-4986
    Schlagwort(e): N-terminal sequencing ; glycoprotein ; glycan analysis ; covalent immobilization ; mass spectrometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The characterization of site-specific glycosylation is traditionally dependent on the availability of suitable proteolytic cleavage sites between each glycosylated residue, so that peptides containing individual glycosylation sites are recovered. In the case of heavily glycosylated domains such as theO-glycosylated mucins, which have no available protease sites, this approach is not possible. Here we introduce a new method to gain site-specific compositional data on the oligosaccharides attached to a single amino acid. Using a model glycopeptide from a mutant human albumin Casebrook, glycosylated PTH-Asn was recovered after sequential solid-phase Edman degradation, subjected to acid hydrolysis and the sugars were identified by high performance anion exchange chromatography with pulsed amperometric detection. The PTH-Asn(Sac) derivative was further characterized by ionspray mass spectrometry. Comparison between an endoproteinase Glu-C glycopeptide and a tryptic glycopeptide showed that the oligosaccharide attached to Asn494 was stable after at least 10 cycles of Edman degradation.
    Materialart: Digitale Medien
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  • 6
    ISSN: 0570-0833
    Schlagwort(e): fluorine compounds ; mass spectrometry ; NMR spectroscopy ; phosphorus compounds ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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