Impact of Hydrophobic Chains in Five-Coordinate Glucoconjugate Pt(II) Anticancer Agents

This study describes new platinum(II) cationic five-coordinate complexes (1-R,R’) of the formula [PtR(NHC)(dmphen)(ethene)]CF3SO3 (dmphen = 2,9-dimethyl-1,10-phenanthroline), containing in their axial positions an alkyl group R (methyl or octyl) and an imidazole-based NHC-carbene ligand with a substituent R’ of variable length (methyl or octyl) on one nitrogen atom. The Pt–carbene bond is stable both in DMSO and in aqueous solvents. In DMSO, a gradual substitution of dmphen and ethene is observed, with the formation of a square planar solvated species. Octanol/water partitioning studies have revealed the order of hydrophobicity of the complexes (1-Oct,Me > 1-Oct,Oct > 1-Me,Oct > 1-Me,Me). Their biological activity was investigated against two pairs of cancer and non-cancer cell lines. The tested drugs were internalized in cancer cells and able to activate the apoptotic pathway. The reactivity of 1-Me,Me with DNA and protein model systems was also studied using UV–vis absorption spectroscopy, fluorescence, and X-ray crystallography. The compound binds DNA and interacts in various ways with the model protein lysozyme. Remarkably, structural data revealed that the complex can bind lysozyme via non-covalent interactions, retaining its five-coordinate geometry

Pyridine Ruthenium(III) complexes entrapped in liposomes with enhanced cytotoxic properties in PC-3 prostate cancer cells

The first aim of the present study is the development of a new ruthenium(III) complex, belonging to NAMI-A class, with a potentially high cytotoxic ability. The presence of a fully protected sugar moiety as ruthenium ligand should increase the complex ability to cross cellular membranes. Furthermore, it sets this molecule in the area of biocompatible agents as tumor drug. The second, more relevant, purpose is to verify the ruthenium complexes activity after loading into liposomes. We reported the characterization and in vitro biological assays of pyridine derivatives of ruthenium complexes loaded into Egg L-α-phosphatidylcholine cholesterol/DSPE-PEG liposomes. Dynamic light scattering estimates that the sizes of all obtained liposomes are in the 100 nm range. This value is suitable for in vivo use. The loading ability and release kinetic allowed selecting the best ratio between the lipid fraction and metal to be tested in cellular experiments. The growth inhibitory effects of both liposomal and free complex in PC-3 prostate cancer cell lines demonstrate a high cytotoxic ability of the liposome entrapped ruthenium (III) complex suggesting additional role further the antimetastatic function

Intermolecular Cross-coupling between 2-Olefin and 1-Allyl Ligands in Cationic Platinum(II) and Palladium(II) Complexes

The n1-allyl platinum and palladium cationic complexes tridentate neutral pincer ligand [(PNP)M(n1-CH2CH=CHR1)]+ (1, PNP = 2,6-bis-diphenylphosphinomethylpyridine) undergo intermol. attack of the terminal gamma-carbon atom of the allyl system at the coordinated olefin of dicationic platinum and palladium complexes [(PNP)M(n2-CH2=CHR)]2+ (2), producing binuclear species [(PNP)M(n2:n1-CH2=CHCHR1CHRCH2)M(PNP)]3+ (4), in which the metal formerly p-coordinated becomes s-bonded, and the metal formerly s-bonded becomes p-coordinated. The reaction can be run catalytically with respect to the addn. of ethylene to a n1-allyl complex, using the dicationic ethylene complex as catalyst

Chiral Recognition in Silver(I) Olefin Complexes with Chiral Diamines. Resolution of Racemic Alkenes and NMR Discrimination of Enantiomers.

The fragment [(chiral diamine)Ag]+ is a very useful reagent, both for the resoln. of racemic alkenes and for the 1H or 13C NMR detn. of the enantiomeric abundances of chiral olefinic compds

Catalytic coupling of ethylene and internal olefins by dicationic palladium(II) and Platinum(II) complexes: switching from hydrovinylation to cyclopropane ring formation

The dicationic palladium(II) and platinum(II) complexes [(PNP)M(C2H4)](BF4)2 (1a, M = Pt; 1b, M = Pd; PNP = 2,6-bis((diphenylphosphino)methyl)pyridine) and [(PPP)Pt(C2H4)](BF4)2 (7; PPP = triphos) catalyze a cross-coupling reaction of ethylene with tri- and tetrasubstituted olefins, which can lead to both hydrovinylation and cyclopropanation products. The product ratio is strongly affected by the choice of the ligand and of the metal, the two limiting cases being 1a and 7, which selectively give the hydrovinylation and the cyclopropanation products, resp

Catalytic hydroalkylation of olefins by stabilized carbon nucleophiles promoted by dicationic platinum(II) and palladium(II) complexes

The coordinated olefin in dicationic platinum(II) and palladium(II) complexes [M(PNP)(olefin)]-(SbF6)2 (M=Pt, Pd; PNP=2,6-bis(diphenylphosphinomethyl)pyridine; olefin=ethylene, propylene) reacts with β-dicarbonyl compounds (pentane-2,4-dione and methyl-3-oxobutanoate). If the proton released after the nucleophilic attack is trapped by a base, stable σ-alkyl derivatives [(PNP)M-CH2-CH(R)CH(Ac)COR0]SbF6 (R=H,Me;R0 =Me, OMe) are formed; otherwise theM-Cσ-bond can be cleaved by the proton, in the rate-determining step of a catalytic cycle that leads to the alkylated dicarbonyl compound.Theβ-diketone is intrinsically more reactive than theβ-ketoester, but in the catalytic reaction of the former an inhibition effect is observed in the case of the platinum catalyst