Synthesis, Characterization and Biological Activity of Palladium(II) Complexes Bearing Trans-cinnamaldehyde-derived Thiosemicarbazones

Cancer comprises approximately 100 diseases characterized by uncontrolled cell proliferation and metastatic potential. Despite the widespread use of cisplatin, its adverse effects motivate the development of new metal-based anticancer agents. This study reports the synthesis, characterization, and biological evaluation of two palladium(II) complexes containing trans-cinnamaldehyde-derived thiosemicarbazones and triphenylphosphine. Structural analyses confirmed the proposed coordination mode, while solution studies indicated chemical equilibrium for one complex. Both compounds exhibited cytotoxic activity against certain human cancer cell lines. Notably, Pd-OMe showed greater potency and selectivity than cisplatin against the cisplatin-resistant ovarian carcinoma cell line A2780cis and promising activity against HepG2 cells. Binding studies with guanosine suggested that the complexes may interact with DNA nucleobases, supporting their potential mechanism of antitumor action. These findings indicate that the synthesized palladium(II) complexes are promising candidates for further anticancer investigations.