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  • 1
    ISSN: 1612-1112
    Keywords: Capillary gas chromatography ; Natural products ; Citrus analysis ; Pre-separation by gel-permeation ; Pre-column
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Gaschromatographie von Naturstoffen wird durch nicht-flüchtige Anteile sehr erschwert. Störungen erfolgen durch Krackung und Katalysatorwirkung im Einspritzblock, Geisterpeaks und Grundlinienversatz. Mittels einer einfachen Gelchromatographie-Vortrennung wird eine Verbesserung der Citrusölanalytik beschrieben. Werden die höhermolekularen Stoffe nicht benötigt, kann man diese durch Verwendung einer Vorsäule am Gaschromatographen ausschalten. Ein einfacher Umbau am GC Gerät wird angegeben.
    Notes: Summary GC separation of natural products is upset by nonvolatile compounds. The problems arise from thermal and catalytic cracking in the injector, from ghost peaks and base line drift. A treatment is shown for obtaining an improvement in citrus analysis by using simple gelpermeation chromatography for pre-separation. A second method describes the separation of the high relative molecular mass compounds with a pre-column GC-equipment. A simple conversion is demonstrated for this modification of GC apparatus.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0570-0833
    Keywords: Natural products ; Biosynthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The principle features of the biosynthesis of natural products have been elucidated during the past thirty years by the use of isotopic methods. It was discovered that large groups of natural products originate from the same biosynthetic precursor - the key building block. The conversion of key building blocks into biologically active natural products serves as a model for the development of more efficient syntheses in chemistry. In medicine, information about key building blocks permits the elucidation and therapy of metabolic diseases.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 98-111 
    ISSN: 0570-0833
    Keywords: Mass spectrometry ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectrometry is a very useful method for the determination of the structure of organic compounds although the technique has not yet been widely employed in this field. Of particular interest is the high sensitivity of the instrument, making possible the use of very small amounts of sample, and the information obtainable regarding the size of the molecule and position of the groups therein. A certain volatility is required and the choice of a suitable derivative is, therefore, sometimes of importance. The fragmentations of the molecules in the ion source may be considered as reactions of “carbonium ions without solvent.” The application of the method in the determination of the structure of some natural products is outlined, using lipids, amino acids, peptides and alkaloids as examples.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 178-195 
    ISSN: 0570-0833
    Keywords: Enzyme catalysis ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Micro-organisms form enzymes that catalyze many reactions which are difficult to carry out in the laboratory or which involve many steps. Enzymes even react with substances which are normally foreign to them. The frequently high stereospecificity of microbiological reactions is of particular significance. The most important types of reactions are: hydroxylations, dehydrogenations (oxidations), and hydrogenations (reductions), cleavage of ester and C-C bonds, and transglycosidations. The variety of the compounds converted is extremely great.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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