Sabrina Autzen

University Hospital Essen, Essen, North Rhine-Westphalia, Germany

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Publications (3)6.04 Total impact

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    ABSTRACT: Six copper(II) complexes of tetracoordinating, pyridinyl-containing 14-membered macrocycles with varying ratios of nitrogen and oxygen donor atoms were prepared and characterized by IR, UV/Vis, and EPR spectroscopy and cyclic voltammetry. A distorted tetragonal coordination of the copper center in the solid-state was established by X-ray crystallography for the tetraazamacrocyclic complex Cu-3 carrying a methoxybenzyl pendent arm and the trioxaaza complex Cu-6. The superoxide dismutase-like activity of the CuII complexes was investigated by inhibition of NADH oxidation. Although the UV/Vis and EPR spectra of the complexes were strongly affected when the coordinating nitrogen atoms were successively replaced by oxygen atoms, no significant change in their reactivity towards superoxide was observed. In all cases a 1:1 or 1:2 stoichiometry for the reaction with superoxide was found, with the exception of the methoxybenzyl-substituted tetraaza complex, which showed a low catalytic activity with a turnover number of about 10. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
    Berichte der deutschen chemischen Gesellschaft 03/2003; 2003(7):1401 - 1410. · 2.94 Impact Factor
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    ABSTRACT: Iron(III) complexes of macrocyclic tetraaza ligands [Fe(III)-1−Fe(III)-3] were investigated for their putative catalase-like properties under physiological conditions: i.e., in aqueous solution at pH = 7.0−7.4 and at micromolar concentrations of the catalyst and hydrogen peroxide. Complex Fe(III)-1, originally studied by Busch et al. as a catalase model, at pH = 4.6, only degrades hydrogen peroxide to oxygen as a minor reaction at this pH (< 1% O2 yield). Experiments with the analogous complex Fe(III)-2 at pH = 7.2 found that no oxygen was formed under physiological conditions, although hydrogen peroxide was decomposed to an extent of more than 50%. Complex Fe(III)-3 produced oxygen on reaction with H2O2, but only in stoichiometric amounts. Thus, the decomposition of hydrogen peroxide by these iron(III) complexes cannot reasonably be described as a catalase-like activity.
    Annalen der Chemie und Pharmacie 07/2001; 2001(16):3119 - 3125. · 3.10 Impact Factor
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    Sabrina Autzen
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    ABSTRACT: Die Bildung reaktiver Sauerstoffspezies nimmt in biologischen Systemen in der Regel ihren Ausgang von der Reduktion des molekularen Sauerstoffs. Typische Enzyme, die mit den Zwischenprodukten der Sauerstoffreduktion reagieren können und dabei zur Entgiftung dieser reaktiven Sauerstoffspezies beitragen, sind z. B. Katalasen und Superoxiddismutase (SOD). Die Arbeit beinhaltet die Synthese von 14-gliedrigen, pyridinhaltigen Makrozyklen und deren Eisen(III)- und Kupfer(II)-Komplexe. Ziel war die Untersuchung der Eisen(III)-Komplexe bezüglich ihrer Wasserstoffperoxid-abbauenden Aktivität in Hinblick auf potentielle katalasemimetische Eigenschaften. Für den Einsatz in biologischen Systemen erheben wir die Forderung, daß "echte" Katalasemimetika Wasserstoffperoxid nur zu den Produkten Sauerstoff und Wasser abbauen und diese in wäßrigen Systemen im physiologisch relevanten pH-Bereich und bei Wasserstoffperoxid-Konzentrationen <10 µM wirksam sein sollen. Die Kupfer(II)-Komplexe der gleichen Liganden wurden aufgrund der zu erwartenden Reaktion mit Superoxid hergestellt. Dieser Verbindungstyp gibt weitere Hinweise auf das Reaktionsverhalten der Klasse dieser Verbindungen in Gegenwart von reaktiven Sauerstoffspezies und ergänzt das noch lückenhafte Schema der Superoxiddismutase-Mimetika.