Abstract (eng)
With over 14 million new cases of cancers worldwide (2012) and over 8.2 million cancer related deaths, there is a strong interest in the development of new drugs fighting this disease. Despite recent advances in chemotherapy, the goal to develop agents with a broad range of application, high selectivity and low toxicity is still unachieved.
In this thesis new cytotoxic compounds were developed based on previous structures containing a tetracyclic carbazole skeleton of the ellipticine quinone type with cytotoxic properties. Tetracyclic analogues of this compound endowed with a basic N,N-dimethylethanamine side chain were synthesised. Subsequently, the tetracyclic ring system was expanded by a benzene ring leading to the pentacyclic calothrixin skeleton, which is known to possess cytotoxic properties. Subsequently, calothrixin isomers with the same side chain were synthesised. In the following, the compounds were subjected to viability assays in which derivatives of the tetracyclic series demonstrated the highest cytotoxic potential. Subsequent side chain modifications and further biological tests were performed.
As a result, three main questions were answered:
Does the substitution of the pyridine system by other pi-electron deficient heterocycles (pyrazine, pyrimidine, pyridazine) enhance the antiproliferative activity of the compounds?
Does the expansion of the pi-electron deficient system by a further benzo-annulation, which leads to calothrixin isomers, enhance the cytotoxic properties? The rationale for this modification is the documented cytotoxic properties of the calothrixins, which are natural compounds of Calothrix cyanobacteria.
Can the antiproliferative activity be enhanced by linking different basic substituents to the skeleton?