Schlosser, Julika

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Schlosser, Julika

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    Photocontrolled Binding of Styrylnaphthyridine Ligands to Abasic Site‐Containing DNA by Reversible [2+2] Cycloaddition and Cycloreversion
    (2024)
    Schlosser, Julika 
    ;
    Ihmels, Heikoorcid-logo
    Five novel styrylnaphthyridine derivatives were synthesized and shown to operate as photoswitchable, selective ligands for abasic site‐containing DNA (AP‐DNA), which is an important therapeutic and diagnostic target. These compounds associate with AP‐DNA with binding constants of 0.5–8.4×10 4 M −1 as shown by photometric and fluorimetric titrations. Specifically, these ligands bind preferentially to AP‐DNA relative to regularly paired duplex DNA. As a special feature, the association of these ligands with DNA can be controlled by means of a reversible [2+2] photocycloaddition. Upon irradiation at 420 nm the photodimer is formed, which does not bind to AP‐DNA. In turn, the naphthyridine is regained with excitation at 315 nm. Most notably, this photoinduced deactivation and release of the DNA ligand can be performed in situ in the presence of AP‐DNA, thus providing a tool for on‐demand delivery of a DNA binder. Overall, these results provide a promising starting point for the development of functional AP‐DNA ligands whose bioactivity can be modulated by light with local and temporal control.
    Source Type:Article
    DOI:10.1002/chem.202400423
      3
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    Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[<i>c</i>]quinolizinium ions
    (2024)
    Schlosser, Julika 
    ;
    Fedorova, Оlga A.orcid-logo
    ;
    Fedorov, Yu. V. 
    ;
    Ihmels, Heikoorcid-logo
    The photoreactions of selected styrylpyridine derivatives to the corresponding benzo[ c ]quinolizinium ions are described. It is shown that these reactions are more efficient in aqueous solution (97–44%) than in organic solvents (78–20% in MeCN). The quinolizinium derivatives bind to DNA by intercalation with binding constants of 6–11 × 10 4 M −1 , as shown by photometric and fluorimetric titrations as well as by CD- and LD-spectroscopic analyses. These ligand–DNA complexes can also be established in situ upon irradiation of the styrylpyridines and formation of the intercalator directly in the presence of DNA. In addition to the DNA-binding properties, the tested benzo[ c ]quinolizinium derivatives also operate as photosensitizers, which induce DNA damage at relative low concentrations and short irradiation times, even under anaerobic conditions. Investigations of the mechanism of the DNA damage revealed the involvement of intermediate hydroxyl radicals and C-centered radicals. Under aerobic conditions, singlet oxygen only contributes to marginal extent to the DNA damage.
    Source Type:Article
    DOI:10.3762/bjoc.20.11
      4
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    Photoinduced Reactions of Styrylpyridine Derivatives for the In Situ Formation of Selective Ligands for Apyrimidinic DNA
    (2023)
    Schlosser, Julika 
    ;
    Stötzel, Nils 
    ;
    Fedorov, Yu. V. 
    ;
    Ihmels, Heikoorcid-logo
    The photocyclization reaction of sterically demanding styrylpyridine derivatives was investigated and shown to depend on the type of substituent. With this method, a 2,2‐diphenyl‐1,3‐benzodioxolo‐annelated benzo[ c ]quinolizinium was synthesized, and its association with regular and abasic site‐containing DNA (AP‐DNA) was investigated by absorption, fluorescence, circular and linear dichroism spectroscopy. Specifically, this ligand binds preferentially to AP‐DNA relative to regular duplex DNA, and the AP‐DNA/ligand complex is formed in situ upon irradiation of the styrylpyridine substrate in the presence of the DNA.
    Source Type:Article
    DOI:10.1002/cptc.202300159
      2
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    Selective Fluorimetric Detection of Pyrimidine Nucleotides in Neutral Aqueous Solution with a Styrylpyridine-Based Cyclophane
    (2023)
    Schlosser, Julika 
    ;
    Hebborn, Julian Felix Maria
    ;
    Berdnikova, Daria V.orcid-logo
    ;
    Ihmels, Heikoorcid-logo
    A styrylpyridine-containing cyclophane with diethylenetriamine linkers is presented as a host system whose association with representative nucleotides was examined with photometric and fluorimetric titrations. The spectrometric titrations revealed the formation of 1:1 complexes with log Kb values in the range of 2.3–3.2 for pyrimidine nucleotides TMP (thymidine monophosphate), TTP (thymidine triphosphate) and CMP (cytidine monophosphate) and 3.8–5.0 for purine nucleotides AMP (adenosine monophosphate), ATP (adenosine triphosphate), and dGMP (deoxyguanosine monophosphate). Notably, in a neutral buffer solution, the fluorimetric response to the complex formation depends on the type of nucleotide. Hence, quenching of the already weak fluorescence was observed with the purine bases, whereas the association of the cyclophane with pyrimidine bases TMP, TTP, and CMP resulted in a significant fluorescence light-up effect. Thus, it was demonstrated that the styrylpyridine unit is a useful and complementary fluorophore for the development of selective nucleotide-targeting fluorescent probes based on alkylamine-linked cyclophanes.
    Source Type:Article
    DOI:10.3390/chemistry5020082
      2