Synthesis and cytotoxicity studies of Cu(I) and Ag(I) complexes based on sterically hindered β-diketonates with different degrees of fluorination

Design, synthesis, and in vitro antitumor properties of Cu(I) and Ag(I) phosphane complexes supported by the anions of sterically hindered β-diketone ligands, 1,3-dimesitylpropane-1,3-dione (HLMes) and 1,3-bis(3,5-bis(trifluoromethyl)phenyl)-3-hydroxyprop-2-en-1-one (HLCF3) featuring trifluoromethyl or methyl groups on the phenyl moieties have been reported. In order to compare the biological effects of substituents on the phenyl moieties, the analogous copper(I) and silver(I) complexes of the anion of the parent 1,3-diphenylpropane-1,3-dione (HLPh) ligand were also synthesized and included in the study. In the syntheses of the Cu(I) and Ag(I) complexes, the phosphane coligands triphenylphosphine (PPh3) and 1,3,5-triaza-7-phosphaadamantane (PTA) were used to stabilize silver and copper in the +1 oxidation state, preventing the metal ion reduction to Ag(0) or oxidation to Cu(II), respectively. X-ray crystal structures of HLCF3 and the metal adducts [Cu(LCF3)(PPh3)2] and [Ag(LPh)(PPh3)2] are also presented. The antitumor properties of both classes of metal complexes were evaluated against a series of human tumor cell lines derived from different solid tumors, by means of both 2D and 3D cell viability studies. They display noteworthy antitumor properties and are more potent than cisplatin in inhibiting cancer cell growth.

Anticancer potential of copper(i) complexes based on isopropyl ester derivatives of bis(pyrazol-1-yl)acetate ligands

In this paper, the isopropyl ester derivatives LOiPr and L2OiPr of bis(pyrazol-1-yl)acetic acid and bis(3,5-dimethyl-pyrazol-1-yl)acetic acid were used as chelators for the preparation of new Cu(i) phosphane complexes 1-4. They were synthesized by the reaction of [Cu(CH3CN)4]PF6 and triphenylphosphine or 1,3,5-triaza-7-phosphaadamantane with LOiPr and L2OiPr ligands, in acetonitrile or acetonitrile/methanol solution. The authenticity of the compounds was confirmed by CHN analysis, 1H-, 13C- and 31P-NMR, FT-IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). Furthermore, the electronic and molecular structures of the selected Cu(i) coordination compound 3 were investigated by synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), and the local structure around the copper ion site was studied combining X-ray absorption fine structure (XAFS) spectroscopy techniques and DFT modelling. Triphenylphosphine as a coligand confers to [Cu(LOiPr)(PPh3)]PF6 (1) and [Cu(L2OiPr)(PPh3)]PF6 (3) a significant antitumor activity in 3D spheroidal models of human colon cancer cells. Investigations focused on the mechanism of action evidenced protein disulfide-isomerase (PDI) as an innovative molecular target for this class of phosphane copper(i) complexes. By hampering PDI activity, copper(i) complexes were able to cause an imbalance in cancer cell redox homeostasis thus leading to cancer cell death - a non-apoptotic programmed cell death.

Copper-Based Complexes with Adamantane Ring-Conjugated bis(3,5-Dimethyl-pyrazol-1-yl)acetate Ligand as Promising Agents for the Treatment of Glioblastoma

The new ligand L2Ad, obtained by conjugating the bifunctional species bis(3,5-dimethylpyrazol-1-yl)-acetate and the drug amantadine, was used as a chelator for the synthesis of new Cu complexes 1-5. Their structures were investigated by synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and by combining X-ray absorption fine structure (XAFS) spectroscopy techniques and DFT modeling. The structure of complex 3 was determined by single-crystal X-ray diffraction analysis. Tested on U87, T98, and U251 glioma cells, Cu(II) complex 3 and Cu(I) complex 5 decreased cell viability with IC50 values significantly lower than cisplatin, affecting cell growth, proliferation, and death. Their effects were prevented by treatment with the Cu chelator tetrathiomolybdate, suggesting the involvement of copper in their cytotoxic activity. Both complexes were able to increase ROS production, leading to DNA damage and death. Interestingly, nontoxic doses of 3 or 5 enhanced the chemosensitivity to Temozolomide.