Bis(dimethylsulfoxide)carbonateplatinum(ii), a new synthon for a low-impact, versatile synthetic route to anticancer Pt carboxylates

New Oxaliplatin-Pyrophosphato Analogs with Improved In Vitro Cytotoxicity

Two new Pt(II)-pyrophosphato complexes containing the carrier ligands cis-1,3-diaminocyclohexane (cis-1,3-DACH) and trans-1,2-diamine-4-cyclohexene (1,2-DACHEX), variants of the 1R,2R-diaminocyclohexane ligand present in the clinically used Pt-drug oxaliplatin, have been synthesized with the aim of developing new potential antitumor drugs with high bone tropism. The complexes are more stable at physiological pH than in acid conditions, with Na2[Pt(pyrophosphato)(cis-1,3-DACH)] (1) slightly more stable than [Pt(dihydrogenpyrophosphato)(1,2-DACHEX)] (2). The greater reactivity at acidic pH ensures a greater efficacy at the tumor site. Preliminary NMR studies indicate that 1 and 2 react slowly with 5'-GMP (used as a model of nucleic acids), releasing the pyrophosphate ligand and affording the bis 5'-GMP adduct. In vitro cytotoxicity assays performed against a panel of four human cancer cell lines have shown that both compounds are more active than oxaliplatin. Flow cytometry studies on HCT116 cells showed that the pyrophosphato compounds with the non-classical 1,3- and 1,4-diaminocyclohexane ligands (1 and 4) are the most capable to induce cells' death by apoptosis and necrosis.

Polytopic carriers for platinum ions: from digalloyl depside to tannic acid

Multinuclear platinum complexes of the natural antioxidant tannic acid and its aglycone part methyl digallate can be prepared via an environmentally friendly, solvent-free process exploiting the convenient precursor [PtCO₃(Me₂SO-S)₂].

A new amido-phosphine of dichloroacetic acid as an active ligand for metals of pharmaceutical interest. Synthesis, characterization and tests of antiproliferative and pro-apoptotic activity

We herein describe the synthesis and characterization of the new amido-phosphinic ligand 3,7‑bis(dichloroacetyl)‑1,3,7‑triaza‑5‑phosphabicyclo[3.3.1]nonane (DCP), a derivative of dichloroacetic acid (DCA), whose ability to reverse the suppressed mitochondrial apoptosis in cancer cells is known. DCP was obtained by a double N-acylation of PTA (1,3,5‑triaza‑7‑phosphaadamantane) occurring with loss of CH₂, in appropriate conditions_. Due to the hindered rotation around the amidic CN bonds, three rotameric forms of DCP were observed, whose ratio in solution was dependent on the solvent, while the X-ray crystal structure of DCP showed an opposite orientation of the two amidic carbonyl groups (anti rotamer). The lipophilic, air and thermally stable DCP was found able to act regiospecifically as a P-donor ligand toward soft metal ions. By ligand substitution on appropriate precursors, we obtained the complexes 1-9, where proapoptotic DCA is associated with metal ions of known cytotoxic activity on cancer cells (Pt²⁺, Pd²⁺, Ru²⁺, Re⁺, Au⁺). The antiproliferative activity of DCP and its complexes was tested in vitro, in comparison with cisplatin, on three human tumor cell lines: A2780 (ovarian cisplatin-sensitive), A2780cis (ovarian cisplatin-resistant) and K562 (erythroleukemic). The results showed that the simultaneous presence of DCP (containing two residues of proapoptotic DCA) and Pt(II) produces the best performances with respect to non-platinum complexes. Experiments of pro-apoptotic activity indicated that the antiproliferative activity of the most active DCP-Pt(II) complexes is associated with induction of apoptosis.

Synthesis of new allyl palladium complexes bearing purine-based NHC ligands with antiproliferative and proapoptotic activities on human ovarian cancer cell lines

A series of new palladium allyl complexes bearing purine-based carbenes derived from caffeine, theophylline and theobromine have been prepared and characterized by NMR spectroscopy, and elemental analysis and in two cases by single crystal X-ray diffraction. The cytotoxic and proapoptotic activities of compounds have been determined in vitro on human ovarian cancer A2780 and SKOV-3 cell lines. These experiments have shown that the palladium-allyl fragment induces a general cytotoxicity, but the choice of the supporting ligands is of paramount importance for achieving the best results. In particular complexes 4c, 4d and 5d exhibit a higher antiproliferative effect (IC50: 0.09, 0.81 and 0.85 μM respectively) than cisplatin (IC50: 1.5 μM) on A2780 cells, and 4d (IC50: 1.7 μM vs. 5.94 μM) on SKOV-3 cell line. Moreover in many cases it has been proved that the cytotoxicity of our complexes is associated with the induction of apoptosis.

Solid lipid nanoparticles for the delivery of 1,3,5-triaza-7-phosphaadamantane (PTA) platinum (II) carboxylates

The use of solid lipid nanoparticles (SLN) is a promising route for the delivery of platinum complexes aimed to anticancer activity. This paper describes the production and characterization of SLN suitable for the loading of Pt complexes containing the biocompatible phosphine 1,3,5-triaza-7-phosphaadamantane (PTA) as neutral ligand. After a screening of several lipidic phases, stearic acid-based SLN were identified as the most appropriate for the purpose. They were produced by emulsion-dilution method and then characterized in terms of dimension, polydispersity, time stability, pH balance and morphological aspect. Stearic acid SLN are designed as a system able to coordinate to platinum, acting as anionic carboxylic ligands, replacing the base carbonate of the Pt synthon [PtCO₃(DMSO)₂], where also DMSO can subsequently be substituted by phosphinic ligands, namely PTA. SLN functionalised with Pt-PTA were produced and characterized by this synthetic route. The toxicity of plain SLN and the antiproliferative effect of SLN functionalised with Pt-PTA were evaluated on two human cancer cell lines K562 and A2780. The results indicate that SLN can be exploited as a delivery system for Pt complexes with potential anticancer activity.