Zinc(II) complexes with dithiocarbamato derivatives: structural characterisation and biological assays on cancerous cell lines.

Zinc is one of the most important trace elements in the body and it is essential as a cofactor for the structure and function of a number of cellular molecules including enzymes, transcription factors, cellular signalling proteins and DNA repair enzymes. On the other hand, recent studies have shown that zinc could play a role both in the development of various cancers and in the induction of apoptosis in some cell types, however, no established common relationships of zinc with cancer development and progression have been identified. To date, in our research group different metal-dithiocarbamato complexes have been designed that were expected to resemble the main features of cisplatin together with higher activity, improved selectivity and bioavailability, and lower side-effects. On the basis of the obtained encouraging achievements with other metals (such as gold and copper) we have decided to enlarge the studies to the complexes of zinc(II) using the same ligands. Hereby, we report the results on the synthesis and characterisation of ZnL(2) complexes with five different dithiocarbamato derivatives, such as dimethyl-(DMDT), pyrrolidine-(PyDT), methyl-(MSDT), ethyl-(ESDT) and tert-butyl-(TSDT) sarcosinedithiocarbamate. All the obtained compounds have fully been characterised by means of several spectroscopic techniques. In addition, the crystal structure of [Zn(MSDT)(2)](2) dinuclear complex is also reported. In order to evaluate the in vitro cytotoxic properties, some biological assays have been carried out on a panel of human tumour cell lines sensible and resistant to cisplatin. Some of the tested compounds show cytotoxicity levels comparable or even greater than the reference drug (cisplatin).

Rational design of gold(III)-dithiocarbamato peptidomimetics for the targeted anticancer chemotherapy.

As a further extension of our research work focusing on the development of gold(III)-dithiocarbamato dtc derivatives of oligopeptides as potential anticancer agents, complexes [Au(III)X(2)(dtc-Sar-L-Ser(t-Bu)-O(t-Bu))] (X=Br (1a)/Cl (1b)), [Au(III)X(2)(dtc-AA-Aib(2)-O(t-Bu))] (AA=Sar (sarcosine, N-methylglycine), X=Br (2a)/Cl (2b); AA=D,L-Pro, X=Br (3a)/Cl (3b)), [Au(III)X(2)(dtc-Sar-Aib(3)-O(t-Bu))] (X=Br (4a)/Cl (4b)), and [Au(III)X(2)(dtc-Sar-Aib(3)-Gly-OEt)] (X=Br (5a)/Cl (5b)) (Aib = "alpha"-aminoisobutyric acid, 2-methylalanine) were designed to obtain metal-based peptidomimetics that may specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several human tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy. According to in vitro cytotoxicity studies, complex [Au(III)Cl(2)(dtc-D,L-Pro-Aib(2)-O(t-Bu))] (3b) turned out to be the most effective toward the four human tumor cell lines evaluated (PC3, 2008, C13, and L540), for which the IC(50) values were lower than cisplatin. Remarkably, it showed no cross-resistance with cisplatin itself and was proved to inhibit tumor cell proliferation by inducing almost exclusively late apoptosis/necrosis. Biological results are here reported and discussed in terms of the structure-activity relationship.

Chemical and biological profiles of novel copper(II) complexes containing S-donor ligands for the treatment of cancer.

In the last years, we have synthesized some new platinum(II), palladium(II), gold(I/III) complexes with dithiocarbamato derivatives as potential anticancer drugs, to obtain compounds with superior chemotherapeutic index in terms of increased bioavailability, higher cytotoxicity, and lower side effects than cisplatin. On the basis of the obtained encouraging results, we have been studying the interaction of CuCl2 with methyl-/ethyl-/tert-butylsarcosine-dithiocarbamato moieties in a 1:2 molar ratio; we also synthesized and studied the N,N-dimethyl- and pyrrolidine-dithiocarbamato copper complexes for comparison purposes. The reported compounds have been successfully isolated, purified, and fully characterized by means of several spectroscopic techniques. Moreover, the electrochemical properties of the designed compounds have been studied through cyclic voltammetry. In addition, the behavior in solution was followed by means of UV-vis technique to check the stability with time in physiological conditions. To evaluate their in vitro cytotoxic properties, preliminary biological assays (MTT test) have been carried out on a panel of human tumor cell lines. The results show that cytotoxicity levels of all of the tested complexes are comparable or even greater than that of the reference drug (cisplatin).

Ru(III)-based compounds with sulfur donor ligands: synthesis, characterization, electrochemical behaviour and anticancer activity.

In recent years, Ru(iii) complexes have emerged as a new class of effective anticancer agents against tumors that proved to be resistant to all other chemotherapeutic drugs currently in clinical use. To extend our previous studies on metal complexes containing sulfur-donor ligands, we report here on the synthesis and characterization, by means of several spectroscopic and analytical techniques, some [Ru(RSDT)(3)] and [Ru(2)(RSDT)(5)]Cl complexes with dithiocarbamato ligands derived from methyl/ethyl/tert-butyl esters of sarcosine. Their electrochemical behaviour was also studied by cyclic voltammetry. All the complexes were tested for their cytotoxicity on a panel of human tumor cell lines showing highly significant antitumor activity. The chemical and biological properties of the newly synthesized complexes, were compared with those of [Ru(DMDT)(3)] and [Ru(2)(DMDT)(5)]Cl species (DMDT = N,N-dimethyldithiocarbamate) whose chemical (not biological) characterization has been already reported in literature.

Synthesis, characterization, and comparative in vitro cytotoxicity studies of platinum(II), palladium(II), and gold(III) methylsarcosinedithiocarbamate complexes.

This work reports on the synthesis, characterization, and in vitro cytotoxic activity of some new platinum(II), palladium(II), and gold(III) derivatives of methylsarcosinedithiocarbamate and its S-methyl ester, to study their behavior as potential antitumor agents. The biological activity of these compounds, as determined by growth inhibition and apoptosis induction, has been investigated in both human leukemic promyelocites HL60 and human squamous cervical adenocarcinoma HeLa cell lines, and their activity has been compared to the well-known platinum-based anticancer agent cisplatin. On the basis of these experimental results, [Pd(MSDT)X]n (MSDT = methylsarcosinedithiocarbamate; X = Cl, Br) complexes show a strong dose-dependent growth inhibition of both HL60 and HeLa cells, with IC(50) values slightly higher than those recorded for cisplatin; moreover, [Au(MSDT)X(2)] activity appears significantly higher or, at least, comparable to that of the reference drug. Exposure of both cell lines to [Pd(MSDT)X]n and [Au(MSDT)X(2)] complexes induces apoptosis, as determined by an Apo2.7 assay.