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  • enantioseparation  (2)
  • (S)-Propranolol  (1)
  • DryLab  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 104 (1991), S. 113-128 
    ISSN: 1436-5073
    Keywords: enantioseparation ; liquid chromatography ; chiral recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this brief overview diverse chiral recognition models and chiral host-guest (selector-selectand, SO-SA) relationships which are used in enantioselective chromatography are discussed. In particular it is focussed on aspects of chiral interactions on (a) small molecular “brush type” chiral stationary phases (CSPs) and on (b) biopolymer and synthetic polymer type CSPs. The importance and the great variability of intermolecular SO-SA bindings via complementary contact sites, also in connection with molecule conformations, is stressed. Some representative and selected examples of chromatographic enantioseparations are presented.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1912
    Keywords: (R)-Propranolol ; (S)-Propranolol ; Betaadrenoceptor antagonists ; Stereoselectivity ; Iodocyanopindolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a randomized, double-blind, placebo-controlled, cross-over study 24 healthy volunteers were examined before and 2 h after oral administration of 80 mg (R,S)-, 40 mg (R)- and 40 mg (S)-propranolol · HCI; 8 of them received placebo in an additional run. During exercise on a bicycle ergometer and a rest period the rate pressure product was decreased by 80 mg (R,S)-propranolol · HCl (−32.8%p 〈 0.0001) and 40 mg (S)-propranolol · HCl (−32.3%;p 〈 0.0001), whera 40 mg (R)-propranolol · HCl as well as placebo showed no effect. corresponding binding inhibition experiments using (−)-(125I)iodocyanopindolol in a sarcolemma-enriched cardiac membrane preparation yielded a eudismic ratio of 179 for (S)- over (R)-propranolol. 2 h after oral application, stereospecific HPLC analysis revealed different individual concentrations in plasma of (R)-(22.3 ± 21.7 ng/ml) and (S)-propranolol (30.4 ± 26.9 ng/ml) when 80 mg of (R,S)-propranolol · Hcl was administered. The plasma levels were similar when 40 mg of the pure enantiomer of (R)- (22.7 ± 20.3 ng/ml) or (S)-propranolol · HCl (28.7 ± 22.5 ng/ml) was applied. (R)- and (S)-propranolol are two substances with different pharmacodynamic and pharmacokinetic properties. As there are methods available to produce the optically pure enantiomers, they should be used rather than the racemic mixture.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0899-0042
    Keywords: high-performance liquid chromatography ; nonporous chiral stationary phase ; MICRA NPS ; tert-butyl carbamoylated quinine selector ; weak chiral anion exchanger ; N-protected α-amino acids ; DNP ; DNB ; DNZ ; mobile phase optimization ; DryLab ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this study, tert-butyl carbamoylated quinine as chiral selector was immobilized on nonporous silica (NPS) 1.5 μm particles developed by MICRA, and this new chiral stationary phase (CSP) was packed into a 3.3 cm column (4.6 mm ID). A series of various N-protected α-amino acids was chosen as chiral selectands, including 3.5-dinitrobenzyloxycarbonyl amino acids (DNZ-AAs). In order to optimize the chromatographic conditions with this novel CSP and to apply it to the resolution of acidic analytes the following parameters have been varied and studied: pH of the mobile phase, buffer concentration, and percentage of methanol or acetonitrile in the mobile phase. DryLabR software was applied to optimize enantioseparation by simulating chromatographic functions of experimental conditions for isocratic and/or gradient runs. Thus, we were able to resolve a set of test compounds within several minutes, whereby our attention was particularly drawn to the resolution of DNZ-AA derivatives. Chirality 9:157-161, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0935-6304
    Keywords: High-performance liquid chromatography ; β-methyl amino acids ; enantioseparation ; quinine-derived chiral stationary phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quinine-derived chiral anion-exchange stationary phase was used for the direct high-performance liquid chromatographic separation of the enantiomers of the N-protected unusual β-substituted α-amino acids, β-methylphenylalanine, β-methyltyrosine, β-methyltryptophan, and β-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid. The readily prepared 2,4-dinitrophenyl and tert-butyloxycarbonyl derivatives were well separated, and in most cases the separation of all four stereoisomers of these β-methyl-α-amino acids could be obtained in one chromatographic run. The elution sequences of the enantiomers of the different derivatives were determined and revealed a dependence on the type of the N-protecting group. In this context, the effects of different protecting groups (acetyl, tert-butyloxycarbonyl, benzoyl, 3,5-dinitrobenzoyl, benzyloxycarbonyl, 3,5-dinitrobenzyloxycarbonyl, 2,4-dinitrophenyl, and 9-fluorenylmethoxycarbonyl) on the chromatographic behavior were investigated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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