DNA binding and antitumor activities of platinum(IV) and zinc(II) complexes with some S-alkyl derivatives of thiosalicylic acid

A series of complexes of platinum(IV) (C1-C5) and zinc(II) (C6-C10) with S-alkyl derivatives of thiosalicylic acid were prepared and characterized. The interactions of the complexes with calf thymus DNA were analyzed by absorption (UV-Vis) and emission spectral studies (ethidium bromide displacement studies). The cytotoxic activities of complexes C1-C10 were determined against mouse B cell lymphocytic leukemia cells (BCL1), human B-prolymphocytic leukemia (JVM-13), mouse mammary carcinoma cells (4T1), and human mammary carcinoma cells (MDA-MB-468) and compared to the activities of the free ligand precursors and cisplatin. The cytotoxicities of the platinum(IV) and zinc(II) complexes toward mouse tumor cell lines were higher compared with their effects on human tumor cell lines. The zinc(II) complex C9 showed the highest antitumor activity toward the tested human cell lines, while the platinum(IV) complex C4 exhibited the highest antitumor activity toward mouse BCL1 and 4T1 cells. Both C4 and C9 have ligands derived from S-propyl thiosalicylic acid.