Gold(III) Complexes Activity against Multidrug-Resistant Bacteria of Veterinary Significance

The emergence and spread of multidrug-resistant bacteria are a global concern. The lack of new antibiotics in the pipeline points to the need for developing new strategies. In this sense, gold(III) complexes (G3Cs) could be a promising alternative due to their recently described antibacterial activity. The aim of this study was to evaluate the antimicrobial activity of G3Cs alone and in combination with colistin against pathogenic bacteria from veterinary sources. Minimal inhibitory concentration (MIC) values were determined by broth microdilution and compared with clinically relevant antibiotics. Antibiofilm activity was determined by crystal violet staining. Combinations of selected G3Cs with colistin and cytotoxicity in commercial human cell lines were evaluated. Four and seven G3Cs showed antibacterial effect against Gram-negative and Gram-positive strains, respectively, with this activity being higher among Gram-positive strains. The G3Cs showed antibiofilm activity against Gram-negative species at concentrations similar or one to four folds higher than the corresponding MICs. Combination of G3Cs with colistin showed a potential synergistic antibacterial effect reducing concentrations and toxicity of both agents. The antimicrobial and antibiofilm activity, the synergistic effect when combined with colistin and the in vitro toxicity suggest that G3Cs would provide a new therapeutic alternative against multidrug-resistant bacteria from veterinary origin.

Antitumor and Antiangiogenic Properties of Gold(III) Complexes Containing Cycloaurated Triphenylphosphine Sulfide Ligands

A family of stable anticancer gold(III)-based therapeutic complexes containing cyclometalated triphenylphosphine sulfide ligands have been prepared. The anticancer properties of the newly developed complexes [AuCl₂{κ²-2-C₆H₄P(S)Ph₂}] (1), [Au(κ²-S₂CNEt₂){κ²-2-C₆H₄P(S)Ph₂}]PF₆ (2), [AuCl(dppe){κC-2-C₆H₄P(S)Ph₂}]Cl (3), and [Au(dppe){κ²-2-C₆H₄P(S)Ph₂}][PF₆]₂ (4) were investigated toward five human cancer cell lines [cervical (HeLa), lung (A549), prostate (PC3), fibrosarcoma (HT1080), and breast (MDA-MB-231)]. In vitro cytotoxicity studies revealed that compounds 2-4 displayed potent cell growth inhibition (IC₅₀ values in the range of 0.17-2.50 μM), comparable to, or better than, clinically used cisplatin (0.63-6.35 μM). Preliminary mechanistic studies using HeLa cells indicate that the cytotoxic effects of the compounds involve apoptosis induction through ROS accumulation. Compound 2 also demonstrated significant inhibition of endothelial cell migration and tube formation in the angiogenesis process. Evaluation of the in vivo antitumor activity of compound 2 in nude mice bearing cervical cancer cell (HeLa) xenografts indicated significant tumor growth inhibition (55%) with 1 mg/kg dose (every 3 days) compared with the same dose of cisplatin (28%). These results demonstrate the potential of gold(III) complexes containing cyclometalated triphenylphosphine sulfide ligands as novel metal-based anticancer agents.

Novel phosphine sulphide gold(i) complexes: topoisomerase I inhibitors and antiproliferative agents

Gold(i) increases the cytotoxicity of phosphine sulfide quinolines against cancer cell lines, while heterocycles maintain the TopI inhibitory activity.

Potent and Selective Cytotoxic and Anti-inflammatory Gold(III) Compounds Containing Cyclometalated Phosphine Sulfide Ligands

Four cycloaurated phosphine sulfide complexes, [Au{κ² -2-C₆ H₄ P(S)Ph₂ }₂ ][AuX₂ ] [X=Cl (2), Br (3), I (4)] and [Au{κ² -2-C₆ H₄ P(S)Ph₂ }₂ ]PF₆ (5), have been prepared and thoroughly characterized. The compounds were found to be stable under physiological-like conditions and showed excellent cytotoxicity against a broad range of cancer cell lines and remarkable cytotoxicity in 3D tumor spheroids. Mechanistic studies with cervical cancer (HeLa) cells indicated that the cytotoxic effects of the compounds involve the inhibition of thioredoxin reductase and induction of apoptosis through mitochondrial disruption. In vivo experiments in nude mice bearing HeLa xenografts showed that treatment with compounds 4 and 5 resulted in significant inhibition of tumor growth (35.8 and 46.9 %, respectively), better than that of cisplatin (29 %). The newly synthesized gold complexes were also evaluated for their in vitro and in vivo anti-inflammatory activity through the study of lipopolysaccharide (LPS)-activated macrophages and carrageenan-induced hind paw edema in rats, respectively.

Synthetic, structural, NMR and catalytic studies of phosphinic amide-phosphoryl chalcogenides (chalcogen = O, S, Se) as mixed-donor bidentate ligands in zinc chemistry

Synthesis and catalytic activity of the title compounds are reported.

Alkali/coinage metals – organolithium, organocuprate chemistry

Part 1 of this chapter reviews coordination compounds of the alkali metals that contain a carbon-metal bond, looking firstly at organolithiums involving simple silanes. The use of aryl, alkynyl and N-donor ligands is also discussed. Compounds of the coinage metals - copper, silver and gold - are discussed in Part 2 of the review. Discussion is broken down by metal, with copper being considered first. Compounds containing, among others, alkene, amido and phosphido ligands are discussed, along with the significant amount of work on carbene complexes. This interest in carbene complexes is also noted within the silver and gold sections that follow, with a large number of new compounds being described. Polymeric chains and networks containing silver centres have attracted considerable interest and are described, along with the luminescent properties of a selection of novel gold species. This part of the review is completed by coverage of mixed-coinage metal structures, where the systems are found to display luminescent properties. Here again, the compounds discussed contain at least one carbon-metal bond.