Abstract (eng)
Cisplatin was introduced as chemotherapeutic substance after being approved by the FDA in the late 1970s. Despite its curative potential, cisplatin’s major drawbacks remain its severe side-effects and either acquired or intrinsic resistance of several cancer types. Thus, further
development of novel platinum-based anticancer drugs was carried out. Up to date, two additional platinum(II) agents gained worldwide market approval as chemotherapeutics,
namely carboplatin and oxaliplatin. During the last decades, not only development of platinum-based agents in the oxidation state +II, but also that of platinum(IV) compounds gained more attention, since the latter show several advantages over their precursors: They
allow a better pharmacological fine-tuning due to six instead of four coordination sites, and they open up the possibility of oral administration due to their kinetical inertness. Additionally, systemic toxicity might be reduced since platinum(IV) compounds are activated by reduction inside the tumor tissue. The content of this PhD work was divided in three different projects: In the first project,
reduction of four 13C- and 15N labelled platinum(IV) complexes, synthesized by oxidation and functionalization of either cisplatin or carboplatin, in cancer cell lysates was observed by means of 2D NMR spectroscopy.
Since several ferrocenyl containing compounds show cytotoxic activity, the aim of the second project was to synthesize and characterize the first anticancer platinum(IV) compounds bearing one or two ferrocene moieties in the axial position. By loss of axial ligands upon reduction inside the cell, the antiproliferative potential of both platinum and ferrocenyl compounds could be combined; for all of the synthesized complexes, IC50 values in the low micromolar range in SW480 and CH1 human cancer cell lines could be detected.
In the last project, platinum(IV) complexes were coupled onto biodegradable polyphosphazenes in order to design tumor-targeting agents by taking advantage of the EPR effect. Preliminary in vitro investigations showed promising antiproliferative activity as well as high cellular accumulation of the polymer-platinum(IV) conjugate in three different human cancer cell lines.