Orthopalladated acetophenone oxime compounds bearing thioamides as ligands: Synthesis, structure and cytotoxic evaluation

Abstract

Cleavage reactions involving the halide-bridged [Pd(μ-Cl)(C2,N-aphox)]2 precursor (aphox = acetophenone oxime) with thioamides, in the 1:2 molar ratio, yielded mononuclear cyclopalladated of the type [Pd(C2,N-aphox)(Cl)(L) {L = thiourea (1); N-methylthiourea (2); N,N’-dimethylthiourea (3); N-phenylthiourea (4); N,N’-diphenylthiourea (5); thioacetamide (6) and benzothioamide (7)} which were characterized by elemental analyses, infrared and 1H- and 13C{1H}-NMR spectroscopies. The crystal and molecular structures of 1, 3 and 6 were determined by single-crystal X-ray diffraction studies. The cytotoxicity of the cyclopalladated compounds has been evaluated against a panel of murine {breast (4T1) and melanoma (B16F10-Nex2)} and human {melanoma (A2058, SK-Mel-110 and SK-Mel-05), oral squamous cell carcinoma (Cal27), hepatocellular carcinoma (HepG2)} cancer cell lines. All studied compounds were cytotoxic for the seven cancer cell lines studied and in general, most cyclopalladated compounds obtained in this work were more active than cisplatin to the seven tumor cell lines evaluated.