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  • 1
    Electronic Resource
    Electronic Resource
    Studies on pyrazinyl-pyrazylidene tautomerism of pyrazine-acetonitrile derivatives (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 179-185 
    Details
    ISSN: 1434-4475
    Keywords: CNDO/2-MO ; IR ; PMR ; UV
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Gleichgewichte zwischen Pyrazinyl- und 2(1H)-Pyrazyliden-Formen von Pyrazinacetonitril-Derivaten wurden mittels IR-, PMR- und UV-Spektroskopie untersucht. Die Überschußladungen und Dipolmomente der zwei Tautomeren wurden nach dem CNDO/2-MO-Verfahren berechnet.
    Notes: Abstract The equilibria between the pyrazinyl and 2(1H)-pyrazylidene forms of pyrazineacetonitrile derivatives were studied by IR,1H-NMR and UV spectroscopy. The excess charges and dipole moments for the two tautomers were calculated by the CNDO/2-MO method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798408
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  • 2
    Electronic Resource
    Electronic Resource
    Analgesic activity of new pyrazine CH and NH acids and their Hydrophobic and electron donating properties (1985)
    Springer
    Pharmacy world & science 7 (1985), S. 141-145 
    Details
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Analgesic efficacy was determined by the hot plate method for a group of 17 new pyrazine and 3 non-pyrazine CH and NH acids. The biological data were quantitatively related to the hydrophobicity of the compounds, expressed by fragmental constant, and to the orbital energy of the highest occupied molecular orbital, calculated quantumchemically. It has been found that the higher the electron donating properties, the more active is the agent, provided that its hydrophobicity allows it to reach its site of action. The results obtained support the charge transfer model for the biological interaction of analgesic agents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02097250
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  • 3
    Electronic Resource
    Electronic Resource
    The relationship between electron densities and the electronic substituent constants for substituted pyridines (1985)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985), S. 233-237 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron density at the pyridine nitrogen atom and the π-electron density of the pyridine ring were calculated by the CNDO/2-MO method assuming standard bond lengths and angles. The indices were found to correlate with the pKa values of pyridine derivatives and with the electronic substituent constants of the Hammett type. The correlations were best for four-substituted pyridines, making the routine CNDO/2-MO calculations useful for studies of quantitative relations between structure and biological activity of the compounds.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560280206
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  • 4
    Electronic Resource
    Electronic Resource
    Linear and Quadratic Relationships between Retention and Organic Modifier Content in Eluent in Reversed Phase High-Performance Liquid Chromatography: A Systematic Comparative Statistical Study (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 667-676 
    Details
    ISSN: 0935-6304
    Keywords: Reversed-phase high performance liquid chromatography (RP-HPLC) ; relationships between retention and eluent composition ; linear and quadratic models ; statistical comparison of ; evaluation of HPLC columns ; stationary phases ; lipophilicity/hydrophobicity ; log kw ; log P ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Statistical evaluation of linear and quadratic models of chromatographic retention was performed. The relationships describing retention were derived for a set of 23 carefully selected test analytes chromatographed on 18 HPLC columns using methanol-water or acetonitrile-water solutions as mobile phase. It was ascertained whether the square term in the quadratic model improves the description of chromatographic retention in a statistically significant manner. It was also checked whether the retention data extrapolated to a hypothetical neat water eluent (log kw) obtained with the two models and the two organic modifiers are equivalent or should be considered different. The research proved that both models yield similar results and the extrapolated log kw values do not differ statistically significantly in the case of methanol-containing mobile phases. In the case of acetonitrile-water systems the log kw values obtained with linear and quadratic models are normally statistically different. Correlation analysis for log kw vs. log P parameters was performed for data determined on six columns. The best correlations were achieved employing log kw data derived with the linear model for methanol/water systems.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Quantitative relationships between the structure of β-adrenolytic and antihistamine drugs and their retention on an α1-acid glycoprotein HPLC column (1994)
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 8 (1994), S. 125-129 
    Details
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Chromatographic retention parameters of a series of 7 β-adrenolytics and of 12 antihistamine drugs were determined employing an α1-acid glycoprotein (AGP) high-performance liquid chromatographic (HPLC) column. For the group of antihistamines capillary electrophoretic (CE) retention was additionally measured in the presence of either AGP or human serum albumin (HSA). Two series of solutes hydrophobicity parameters were obtained by reversed-phase HPLC on an immobilized artificial membrane (IAM) column. The solutes studied were subjected to molecular modelling and the structural descriptors obtained were applied in studies of quantitative structure-retention (protein binding) relationships (QSRR). It was found that retention on AGP correlates well with the literature on physiological protein binding data. This retention was demonstrated to depend on hydrophobicity: to a lesser extent in the case of β-adrenolytics and strongly in the case of antihistamines. Hydrophobicity, along with molecular width and electron excess charge on aliphatic nitrogen was demonstrated to describe retention of antihistamines on AGP. The AGP column is recommended as a convenient reactor for studies of drug-protein interactions. Preliminary CE data do not correlate with the HPLC data.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bmc.1130080306
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  • 6
    Electronic Resource
    Electronic Resource
    Chromatographic modelling of interactions between melanin and phenothiazine and dibenzazepine drugs (1995)
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 9 (1995), S. 233-237 
    Details
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Differences in drug-melanin interactions were determined for 13 phenothiazine neuroleptics and 2 dibenzazepine thymoleptics by means of high-performace liquid chromatography. The chromatographic column was packed with a stationary phase obtained by chemical immobilization of synthetic L-dopa melanin on silica particles. For six phenothiazines the melanin-binding parameters were also determined by an ultrafiltration method. Correlation between measures of drug-melanin interaction determined chromatographically and by the standard slow-equilibrium method was significant, however moderate. The chromatographic method of assessing interactions between drugs-melanin interaction determined chromatographically and by the standard slow-equilibrium method was significant, however moderate. The chromatographic method of assessing interactions between drugs and melanin permitted reliable and quantitatively comparable data for representative series of solutes to be readily obtained. Such data were subjected to the analysis of quantitative structure-retention relationships (QSRR). It was found that retention of the agents on the immobilized melanin column could be described by two-parameter regression equations comprising the energy of the lowest unoccupied molecular orbital and either the water-accessible surface area of a drug molecule or its hydrophobicity parameter, determined chromatographically on an immobilized artificial membrane column. The QSRR equation derived allows for the estimation of melanin binding based on the structure of a compound candidate, and thus rationalizes predictions of potential toxicity of drugs or drug candidates.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bmc.1130090509
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  • 7
    Electronic Resource
    Electronic Resource
    Binding site for basic drugs on α1-acid glycoprotein as revealed by chemometric analysis of biochromatographic data (1995)
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 9 (1995), S. 211-215 
    Details
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Interactions between α1-acid glycoprotein (AGP) and 52 basic drugs were quantified by means of highperformance liquid chromatography (HPLC). The HPLC retention parameters were related quantitatively to the hydrophobicity and molecular modelling parameters, giving rise to the prediction of relative drug-AGP binding from the chemical structure of a drug. A structural model of one binding site on AGP, common for various classes of drugs, was defined which accounted for the observed and reported differences in binding to AGP. A combination of biochromatography and chemometrics has been presented as a promising new approach in biochemical/pharmacological studies.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bmc.1130090504
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