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  • 1
    Digitale Medien
    Digitale Medien
    Evaluation of the macrocyclic antibiotic vancomycin as a chiral selector for capillary electrophoresis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 496-509 
    Details
    ISSN: 0899-0042
    Schlagwort(e): enantiomeric separations ; macrocyclic antibiotics capillary electrophoresis ; vancomycin ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Vancomycin is one of a family of related macrocyclic glycopeptide antibiotics that were discovered by scientists at the Eli Lilly Company in the 1950s. It has been used to treat severe staphylococcal infections, particularly when bacterial resistance to other antibiotics has developed. Vancomycin is a naturally occurring chiral compound and has a number of stereogenic centers. Furthermore, it contains a variety of functionalities that are known to be useful for enantioselective interactions (e.g., hydrogen bonding groups, hydrophobic pockets, aromatic groups, amide linkages, etc.). The physicochemical properties of vancomycin, including its stability in solution, are discussed as they pertain to capillary electrophoresis. Over 100 racemates were resolved including many nonsteroidal antiinflammatory drugs, antineoplastic compounds and N-derivatized amino acids. Many of these compounds had very high resolution factors. Optimization and the effect of different experimental parameters on the enantioselective separations are discussed. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530060609
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    In vitro study of the metabolic effects of D-amino acids (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 24-29 
    Details
    ISSN: 0899-0042
    Schlagwort(e): CHO cells ; HeLa cells ; lipid peroxidation ; catalase ; D-amino acids ; L-amino acids ; toxicity ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: While the L-configuration of amino acids predominates in all known living systems, D-enantiomers of amino acids have been detected with highly sensitive chromatographic techniques in human physiological fluids. In the present study, the survival of Chinese hamster ovary cells (CHO) and HeLa cells was inhibited by exposure to high concentrations of some D- or L-amino acids. Inhibition of colony formation, though, was not necessarily observed to be chiral-dependent. Some L-amino acids (LAAS) were found to be toxic while other D-amino acids (DAAS) were innocuous in both cultures. This is contradictory to the previous observations that DAAS were generally considered to be harmful. Frequently it was implied, although not experimentally proven, that the LAAS were not toxic. One of the metabolites produced by oxidative deamination of D- or LAAS is hydrogen peroxide (H2O2), a reactive oxygen species (ROS) that is decomposed by catalase. Increased intracellular H2O2 can result in peroxidation of lipids. We measured catalase activity and the lipid peroxide levels (LPO) after incubating cells in either D- or LAAS. The amino acids (AAS) that were found to inhibit colony formation were found to be associated with higher levels of catalase activity and LPO. Therefore, we hypothesize that enhanced ROS generation may be, in part, responsible for the observed toxicity of some amino acids. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Highly enantioselective HPLC separations using the covalently bonded macrocyclic antibiotic, ristocetin A, chiral stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 434-483 
    Details
    ISSN: 0899-0042
    Schlagwort(e): ristocetin A ; macrocyclic antibiotic ; enantiomeric separations ; underivatized amino acids ; chiral stationary phase ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The macrocyclic glycopeptide, ristocetin A, was covalently bonded to a silica gel support and evaluated as a liquid chromatographic (LC) chiral stationary phase (CSP). Over 230 racemates were resolved in either the reversed-phase mode, the normal-phase mode, or the polar-organic mode. The retention behavior and selectivity of this CSP were examined in each mode. Optimization of separations on this column is discussed. The ristocetin A CSP appeared to be complimentary to other glycopeptide CSPs (i.e., vancomycin and teicoplanin). Column stability was excellent. The CSP was not irreversibly altered when going from one mobile phase mode to another. Chirality 10:434-483, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Evaluation of the macrocyclic antibiotic avoparcin as a new chiral selector for HPLC (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 627-660 
    Details
    ISSN: 0899-0042
    Schlagwort(e): avoparcin ; macrocyclic antibiotics ; enantiomeric separations ; chiral stationary phases ; verapamil ; thyroxine ; mephenytoin ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Avoparcin is a macrocyclic glycopeptide antibiotic structurally related to vancomycin, teicoplanin, and ristocetin A. When attached to 5-μm spherical silica gel, the avoparcin proved to be an effective chiral stationary phase (CSP) that could be used in the reversed-phase, normal-phase, and polar-organic modes. The avoparcin CSP was complimentary to the other macrocyclic glycopeptide CSPs in that it could resolve some racemates that the others could not, and vice versa. Some important compounds resolved on the avoparcin CSP include verapamil, thyroxine, mephenytoin, and 2-imidazolidone-4-carboxylic acid. The use of this CSP and the optimization of separations on it are discussed. Avoparcin appears to be a useful addition to this family of CSPs. Chirality 10:627-660, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    A covalently bonded teicoplanin chiral stationary phase for HPLC enantioseparations (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 7 (1995), S. 474-497 
    Details
    ISSN: 0899-0042
    Schlagwort(e): enantiomeric separations ; teicoplanin ; macrocyclic antibiotic ; amino acids ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A macrocyclic glycopeptide antibiotic containing a hydrophobic “tail” is covalently attached to silica gel via linkage chains. This material is extensively evaluated as a chiral stationary phase (CSP) for HPLC. The relevant structural features of the teicoplanin molecule which make it an effective chiral selector are discussed. The teicoplanin CSP appears to have excellent enantioselectivity for native amino acids, peptides, α-hydroxycarboxylic acids, and a variety of neutral analytes including cyclic amides and amines. Enantio-separations can be achieved in the reversed phase, normal phase, and “polar-organic” modes. This chiral selector is stable and the integrity of the CSP is excellent in all separation modes. Hence it can be considered a highly effective multimodal column. Optimization of these separations is discussed in terms of both selectivity and efficiency. Results indicate that the surface loading of the chiral selector affects all relevant separation parameters. A hypothesis is proposed to explain the enhanced efficiency obtained when using teicoplanin CSPs with higher surface coverage. It appears that teicoplanin is a widely applicable, highly effective chiral selector for HPLC enantioseparations. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530070614
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