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  • 1
    Electronic Resource
    Electronic Resource
    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
    Keywords: enantiomeric separations ; macrocyclic antibiotics capillary electrophoresis ; vancomycin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060609
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  • 2
    Electronic Resource
    Electronic Resource
    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
    Keywords: CHO cells ; HeLa cells ; lipid peroxidation ; catalase ; D-amino acids ; L-amino acids ; toxicity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    D-amino acid levels in human physiological fluids (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 375-378 
    Details
    ISSN: 0899-0042
    Keywords: urine ; plasma ; cerebrospinal fluid ; amniotic fluid ; D-pipecolic acid ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plasma, urine, cerebrospinal fluid (CSF), and amniotic fluid were examined to determine whether free D-amino acids were present and if so at what levels. It was found that D-amino acids exist in all physiological fluids tested, but that their level varied, considerably. The lowest levels of D-amino acids were usually found in amniotic fluid or CSF (almost always 〈1% of the corresponding L-amino acid). The highest levels were found in urine (usually tenth percent to low percent levels). Pipecolic acid seemed to be different from the other amino acids tested in that it was excreted primarily as the D-enantiomer (often 〉90%). Correspondingly high levels of D-pipecolic acid were not found in plasma. Some of the trends found in this work seemed to be analogous to those found in a recent rodent study. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050519
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  • 4
    Electronic Resource
    Electronic Resource
    Evaluation of enantiomeric purity of selected amino acids in honey (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 270-276 
    Details
    ISSN: 0899-0042
    Keywords: honey ; D-amino acids ; cyclodextrin columns ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly sensitive and accurate HPLC methods were used for the determination of total amounts of proline, leucine and phenylalanine and their enantiomeric ratios in a variety of different honey samples. Significant amounts of D-leucine and D-phenylalanine and relatively low concentrations of D-proline have been found in honeys of different botanical and geographical origins. It is suggested that the enantiomeric ratios of amino acids could be used to test for storage effects, age, and the quality of the processing of the honey. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060409
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  • 5
    Electronic Resource
    Electronic Resource
    Sixth International Symposium on chiral discrimination (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 1-1 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of the concentration and enantiomeric purity of selected free amino acids in fermented malt beverages (beers) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 49-57 
    Details
    ISSN: 0899-0042
    Keywords: racemization ; fermented beverages ; beer ; D-amino acids ; D-leucine ; D-phenylalanine ; D-proline ; cyclodextrin columns ; column switching ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Even though amino acids are important trace components in the brewing of beers, they have not been extensively evaluated in these beverages. Studies involving the enantiomeric composition of these amino acids are even less prevalent. A brief summary of the brewing process for malt beverages is given. The total concentration and enantiomeric composition of three amino acids (leucine, phenylalanine, and proline) were determined in 25 different beers. Proline tended to have the highest average absolute concentration and the lowest percentage of the D-enantiomer in most samples. In some cases the relative amounts of D-phenylalanine and D-leucine exceeded 10% of the individual amino acids. The enantiomeric composition of the amino acids in different beer samples did not vary as extensively as the absolute concentrations. The reason for the concentration differences between proline and the other amino acids is discussed. A knowledge of amino acid concentrations and enantiomeric compositions appears to be useful in characterizing specific beers and brewing processes. © 1996 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Eighth International Symposium on Chiral Discrimination (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 555-555 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    Enantiomeric composition of nicotine in smokeless tobacco, medicinal products, and commercial reagents (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 587-591 
    Details
    ISSN: 0899-0042
    Keywords: snuff ; chewing tobacco ; Turkish tobacco ; Burley tobacco ; Virginia tobacco ; transdermal patches ; gum ; nasal spray ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomeric composition of nicotine in 18 smokeless tobaccos, 3 strains of tobacco leaf, 8 pharmaceutical products, and 4 commercial reagents was determined. The relative amount of the minor enantiomeric component, (R)-(+)-nicotine, ranged from ∼0.1% to ∼1.2% of the total nicotine in all samples. In some cases it appears that (R)-(+)-nicotine may be considered one of the five most common alkaloids in tobacco products. The highest level of (R)-(+)-nicotine was found in a commercial transdermal patch. The extraction and purification processes used in obtaining commercial (S)-(-)-nicotine supplies from tobacco do not appear to decrease the amount of (R)-(+)-nicotine present. Chirality 10:587-591, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Evaluation of free D-glutamate in processed foods (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 277-282 
    Details
    ISSN: 0899-0042
    Keywords: D-amino acids ; D-glutamate ; monosodium glutamate ; food analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monosodium glutamate (MSG) is added to many processed foods at significant levels for flavor enhancement. It is also naturally occurring at high levels in some foods. The enantiomeric composition of free glutamate in foods was examined and all foods analyzed were found to contain D-glutamate. The relative percent of D-glutamate in the food products studied depended on the origin of the glutamate. Foods to which MSG was added by the manufacturer had a high total level of MSG but a lower relative percentage of the D-enantiomer (usually less than 0.8%). In comparison, fermented foods tend to have high relative levels of D-glutamate but a lower total amount of the amino acid. The relative percent of D-glutamate in nonfermented foods containing no added MSG was also found to be low compared to fermented products. In some cases the percent D-glutamate could be related to the relative amounts of other food ingredients such as cheese. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060410
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  • 10
    Electronic Resource
    Electronic Resource
    Editors' note (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. iii 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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