Unusual reactivity of cisplatin analogs that bear o-phenylenediamine ligands: Insights for the design of more effective cytotoxic agents

Ruthenium(II) Arene Anticancer Complexes with Redox-Active Diamine Ligands

“…Isosbestic points were not apparent, indicating a multistep reaction pathway. Similar observations have been reported by Kockerbauer and Bednarski for the ligand-based oxidation of ( o -pda)Pt II Cl complexes in water …”

“…Similar observations have been reported by Kockerbauer and Bednarski for the ligand-based oxidation of (o-pda)Pt II Cl complexes in water. 49 The ease with which the hmb complex 2 is oxidized compared to the p-cym complex 1 is related to the increased number of electron-donating substituents on the arene in 2. The presence of electron-donating alkyl groups on the arene has been found to strengthen the Ru-arene bond 50 and effectively increase the electron density on the ruthenium center.…”

Linear free energy relationship for 4-substituted (o-phenylenediamine)platinum(II) dichloride derivatives using quantum mechanical descriptors

“…From a qualitative point of view our results can be used to speculate about an indirect correlation with the biological properties of this class of molecules. According to Kö ckerbauer and Bednarski [32], the 4,5-substituted analogues with Cl and Br presented a higher rate of oxidative decomposition than the parent compound (R = H) and the derivative with R = OCH 3 . This decomposition process, which the mechanism is still unknown, is a side process to the hydrolysis reaction and it is believed to be involved with mutagenic action.…”

“…This kind of aromatic diamine compounds was first considered by Connors and coworkers [30] and afterwards by Hansch and collaborators [31] who proposed a QSAR model correlating mutagenicity in the Ames test to the Hammett electronic parameters for a series of 4-and 4,5-substituted dichloro-1,2-(phenylenediamine)platinum(II). Kö ckerbauer and Bednarski [32] reported in 1996 a quite interesting paper dealing with the chemical stability of this class of molecules. The IC 50 values of two other o-phdPt derivatives were tested for in vitro growth inhibitory activity on three human cancer cell lines and the results were very promising since show basically the same effectiveness found for [Pt(en)Cl 2 ] and cisplatin in the breast cancer cell lines.…”

Synthesis and Characterization of [(1,4‐diamine)dichloro]platinum(II) Compounds Preliminary Studies on their Biological Activity

“…This fact made very difficult their structural determination by conventional analyses, but physical and spectroscopic data obtained were in agreement with the proposed structures. It is worth noting that the aromatic compound 14 was synthesized by Köckerbauer and Bednarski [20] by using a different methodology. On the other hand, the synthesis of compound 12 was carried out by these authors following a completely different synthetic approach [21].…”