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  • 1
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Microchimica acta 104 (1991), S. 113-128 
    ISSN: 1436-5073
    Schlagwort(e): enantioseparation ; liquid chromatography ; chiral recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 30-34 
    ISSN: 0899-0042
    Schlagwort(e): propafenone ; enantiomers ; α1-acid glycoprotein ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The interaction of propafenone enantiomers with human α1-acid glycoprotein was studied using high-performance liquid chromatography. Each of the two optical antipodes interacted with one class of high-affinity binding sites characterized by Ka(R) = (6.18 ± 0.93) × 105 M-1, n(R) = 1.34 ± 0.09 for the (R)-isomer and Ka(S) = (8.93 ± 1.82) × 105 M-1, n(S) = 0.99 ± 0.08 for the (S)-isomer. Nonspecific binding to secondary low-affinity high-capacity binding site(s) was only slightly greater in the case of the (S)-enantiomer (n′k′(S) = (1.06 ± 0.09) × 104 M-1) compared to the (R)-enantiomer (n′k′(R) = (6.87 ± 0.72) × 103 M-1). It was concluded that both enantiomers interact with common single class of high-affinity binding sites on AAG (along with nonspecific binding) exhibiting only slight stereoselectivity for propafenone.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 0899-0042
    Schlagwort(e): chiral recognition ; diphenylethylendiamine ; benzodiazepines ; amino acids ; phthalide ; sulfoxide ; drug ; carbinol ; tetrahydropyrimidine ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Undecanoyl bound 3,5-dinitrobenzoyl-(S,R)-1,2-diphenylethane-1,2-diamine [(1S,2R)-DNB-DPEDA] as chiral selector (SO) has been synthesized and used as a chiral stationary phase (CSP II) for normal-phase enantioselective HPLC. It is compared with the already published diastereomeric (1S,2S)-DNB-DPEDA-derived CSP I and with the “standard” Pirkle DNB-(R)-phenylglycine-derived CSP III. Chromatographic data for about 100 racemic analytes reveal that CSP II is able to separate especially well enantiomers of derivatized aromatic carboxylic acids and analytes having a benzyl substituent bound at the chiral center. However, CSP I was found to be superior to CSP II and III in its general applicability and its ability to resolve enantiomers of heterocyclic drugs. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 0899-0042
    Schlagwort(e): atenolol ; nitrile formation ; stability ; chromatography ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The chemical stability of the acetamido moiety of the β-blocker atenolol toward possible dehydration causing a nitrile formation during an acid-catalyzed chiral derivatization procedure with O,O′-(R,R)-diacylated tartaric acid anhydrides was elucidated. All the necessary reference compounds including the oxazolidine-2-one derivatives of the respective aminopropanols were synthesized, their structures confirmed by various spectroscopic methods, and chromatographically compared using HPLC and GC-MS. In the course of this work it was shown that the acetamido moiety of atenolol is quite stable toward dehydrating agents but shows a significant thermolability, e.g., in the injection system of a GC, which leads to the dehydrated form of atenolol namely, “nitriloatenolol.” © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0899-0042
    Schlagwort(e): atenolol enantiomers ; enantioselective HPLC bioassay ; stereoselective pharmacokinetics ; oxazolidine-2-one derivative ; fluorimetric detection ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An enantioselective HPLC bioassay has been developed relying on extraction of (R)- and (S)-atenolol from alkalinized plasma or serum (pH 〉 12) into dichloromethane containing 5% (v/v) 1-butanol followed by an achiral derivatization of the drug with phosgene leading to (R)- and (S)-oxazolidine-2-one derivatives. Under these conditions there was quantitative conversion of the acetamido group to the corresponding nitrile. These stable derivatives were separated on a (R,R)-diaminocylohexane-dinitrobenzoyl chiral stationary phase [(R,R)-DACH-DNB] using dichloromethane/methanol 98/2 as mobile phase. Determination limits of 0.5 ng for (R)- and 0.6 ng for (S)-atenolol could be achieved using fluorimetric detection. The assay was applied to a human pharmacokinetic study which was performed in a randomized cross-over, double-blind fashion in 12 healthy volunteers, administering single oral doses of 100 mg (R,S)-, 50 mg (R)-, and 50 mg (S)-atenolol AUC0-24 and Cmax values of (R)-atenolol were slightly but significant higher than those of (S)-atenolol. The R/S ratios were 1.09 for AUC(R)/AUC(S) and 1.03 for Cmax (R)/Cmax(S) (P 〈 0.01) respectively after administration of the racemic drug. However, there were no differences between AUC, Cmax, and t½ values of each enantiomer, whether they were administered as single enantiometers or in the form of its racemic mixture. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 0899-0042
    Schlagwort(e): hyperthyroidism ; (R)-4-hydroxypropranolol ; peripheral conversion ; metabolites of propranolol ; negative chronotropic effect ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The inhibiting effect of (R,S)-propranolol on peripheral T4/T3 conversion can be related to the (R)-isomer. The intention of this study is to clarify if (R)-4-hydroxypropranolol, a main metabolite of (R)-propranolol, develops the same or even a stronger effect on peripheral thyroxine metabolism as the parent drug. (R)-4-hydroxypropranolol was synthesized via (R)-4-methoxypropranolol and their optical purity was checked chromatographically. Twenty patients suffering from hyperthyroidism were divided into five groups and treated with (R)-4-hydroxypropranolol · HCl in dosages from 12 to 75 mg per day in a placebo controlled study over a period of 5 days. The serum hormone levels and resting pulse rate were measured. No significant changes of thyroid parameter could be observed but a significant decrease of resting pulse rate under treatment with 75 mg (R)-4-hydroxypropranolol occurred. It could be concluded that (R)-4-hydroxypropranolol possesses negative chronotropic effects but develops no changes in thyroid hormone metabolism in hyperthyroid patients.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 0899-0042
    Schlagwort(e): enantiomers ; chirality ; beta-blockers ; iodocyanopindolol ; cardiology ; adrenergic receptors ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In a randomized, double-blind, cross-over study in 12 healthy volunteers, the effects of single oral doses of 100 mg rac-atenolol were compared during exercise to those of equal amounts of the optically pure enantiomers, i.e., 50 mg (R)- and 50 mg (S)-atenolol. The mean rate pressure product decreased with rac-atenolol (-37%; P 〈 0.01) and half-dosed (S)-atenolol (-35%; P 〈 0.01) to the same extent, whereas (R)-atenolol caused no effect. Radioligand binding studies in beta-adrenergic receptors of the guinea pig heart yielded a eudismic ratio of 46 for (S)- to (R)-atenolol. The mean AUCs, maximal plasma concentrations, and plasma half-lives of the enantiomers were similar regardless of whether they were administered as optically pure enantiomers or as racemic mixture. On the other hand, the AUC of (R)-atenolol was 1.08-fold greater (P 〈 0.01) than that of the (S)-enantiomer. The reason for this finding remains unclear. We conclude that only (S)-atenolol, but not (R)-atenolol, contributes to the beta-blocking effect of currently used rac-atenolol since the same effect can be elicited with the (S)-enantiomer alone. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 0899-0042
    Schlagwort(e): indirect and direct enantioseparation ; chromatographic assignment of absolute configuration ; econazole ; miconazole ; imidazolylethanol ; protein type CSPs (OVM) ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method is described for the synthesis and optical purity determination of (-)-(R)- and (+)-(S)-econazole via the optically pure intermediates, (R)- and (S)-imidazolylethanol, which are available by chromatographic resolution or by fractional crystallization of diastereomeric O,O′-disubstituted (R*;R*)- or (S*;S*)-tartaric acid monoesters of the parent imidazolylethanol racemate. Furthermore, this method allows the chromatographic assignment of the absolute configuration of the chiral center of the imidazolylethanol enantiomers and consequently of econazole enantiomers. In addition, a direct liquid chromatographic enantioseparation method for the determination of the optical purity of (R)- and (S)-econazole and other chiral imidazoles on a protein type CSP (OVM) is described and applied to confirm chromatographically the absolute configuration evaluations. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2017-04-01
    Beschreibung: Analytical Chemistry DOI: 10.1021/acs.analchem.6b03732
    Print ISSN: 0003-2700
    Digitale ISSN: 1520-6882
    Thema: Chemie und Pharmazie
    Standort Signatur Erwartet Verfügbarkeit
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