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  • Drug research  (2)
  • Catalysis  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Oxidation of Polycyclic Aromatic Hydrocarbons Catalyzed by Iron Tetrasulfophthalocyanine FePcS: Inverse Isotope Effects and Oxygen Labeling Studies (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1269-1281 
    Details
    ISSN: 1434-1948
    Keywords: Oxidation ; Catalysis ; Phthalocyanine ; Iron ; Anthracene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iron(III) tetrasulfophthalocyanine (FePcS) was shown to catalyze the oxidation of polycyclic aromatic hydrocarbons by H2O2. Benzo[a]pyrene and anthracene were converted to the corresponding quinones while biphenyl-2,2′-dicarboxylic acid was the main product of phenanthrene oxidation. The mechanism of the anthracene oxidation by H2O2 in the presence of FePcS or by KHSO5 with iron(III) meso-tetrakis(3,5-disulfonatomesityl)porphyrin (FeTMPS) (see Figure 1 for catalyst structures) has been investigated in details by using kinetic isotope effects (KIEs) and 18O labeling studies. KIEs measured on the substrate consumption in the competitive oxidation of [H10]anthracene and [D10]anthracene by FePcS/H2O2 and FeTMPS/KHSO5 were essentially the same, 0.75 ± 0.02 and 0.76 ± 0.06, respectively. These inverse KIEs on the first oxidation step can be explained by the sp2-to-sp3 hybridization change during the addition of an electrophilic oxoiron complex to the sp2 carbon center of anthracene to form a σ adduct (this inverse KIE being enhanced by stronger stacking interactions between the perdeuterated substrate with the macrocyclic catalyst). Although the first oxidation step seems to be the same, different distribution of the oxidation products of anthracene and very different 18O incorporation into anthrone and anthraquinone in catalytic oxidations performed in the presence of H218O suggested that different active species should be responsible for anthracene oxidation in both catalytic systems. All the results obtained are compatible with an involvement of TMPSFeV=O (or TMPS+FeIV=O), having two redox equivalents above the iron(III) state of the metalloporphyrin precursor, while PcSFeIV=O (one redox equivalent above FeIII state of FePcS) was proposed to be the active species in the metallophthalocyanine-based system.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Structure-Activity Relationships of Synthetic Tricyclic Trioxanes Related to Artemisinin: The Unexpected Alkylative Property of a 3-(Methoxymethyl) Analog (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1935-1938 
    Details
    ISSN: 1434-193X
    Keywords: Antiprotozoals ; Artemisinin ; Trioxanes ; Heme ; Structure-activity relationships ; Drug research ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A clear-cut correlation between antimalarial potency and the alkylative property of synthetic tricyclic trioxanes 5-10 is reported. Thus, trioxanes 5 and 7, substituted at the C-5a angular position by a methyl or a cyano group, proved to be completely devoid of antimalarial activity, and did not alkylate the heme model MnIITPP. In contrast, both the anti-Plasmodium activity and the alkylative property were restored in the C-5a-unsubstituted analog 8, bearing a methoxymethyl group at C-3. Reaction of 8 with MnIITPP furnished the covalent adduct 18, resulting from trapping of the methoxymethyl radical by the heme model. All these results reinforce the hypothesis that the metalloporphyrin closely interacts with the peroxide bond of the drug to bring about activation of these trioxane antimalarial agents.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon - Hydrogen Bonds of DNA Sugar Units as Targets for Chemical Nucleases and DrugsAbbreviations are listed in Section 5 at the end of the review. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 34 (1995), S. 746-769 
    Details
    ISSN: 0570-0833
    Keywords: bleomycin ; DNA cleavage ; enediynes ; transition metal complexes ; Drug research ; Bleomycin ; DNA cleavage ; Enediynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This review article focuses on the molecular aspects of DNA cleavage by synthetic chemical nucleases (transition metal complexes endowed with redox properties and DNA affinity) and natural drugs (cytotoxic agents such as bleomycins or enediynes). Unlike deoxyribonucleases, which catalyze the nucleophilic attack of water on the phosphorus atom of a particular phosphodiester entity, these nonhydrolytic DNA-cleavers are able to oxidize the sugar units, generally by hydrogen atom abstraction. Examples of oxidative attack on each of the five different C—H bonds of deoxyribose are known, depending on the nature, structure, type of activation, or mode of DNA interaction of the DNA-cleaver. Further evolution at the site of the initial lesion leads to the release of bases, oxidized deoxyribose units, or oxidized sugar fragments appended to the base or the terminal phosphate. In most cases the loss of a part (at least) of a nucleoside, with the concomitant loss of one base information, primarily induces the cleavage of the DNA strand. For both types of DNA cleavage reagents studied within the two last decades, the modes of activation and DNA binding are presented, as well as the details on the mechanism of deoxyribose oxidative degration. Because of the need for highly efficient and highly specific reagents, the development of new artificial and selective DNA cleavers, supported by an improved knowledge of these different mechanisms of DNA cleavage, is to-day a challenging area in the rational design of antitumoral or antiviral agents, as well as in the field of molecular biology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199507461
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