Design, Synthesis and Pharmacological Evaluation of Three Novel Dehydroabietyl Piperazine Dithiocarbamate Ruthenium (II) Polypyridyl Complexes as Potential Antitumor Agents: DNA Damage, Cell Cycle Arrest and Apoptosis Induction

Cd(II) and Pd(II) Mixed Ligand Complexes of Dithiocarbamate and Tertiary Phosphine Ligands-Spectroscopic, Anti-Microbial, and Computational Studies

Mixed ligand complexes of Pd(II) and Cd(II) with N-picolyl-amine dithiocarbamate (PAC-dtc) as primary ligand and tertiary phosphine ligand as secondary ligands have been synthesized and characterized via elemental analysis, molar conductance, NMR (¹H and ³¹P), and IR techniques. The PAC-dtc ligand displayed in a monodentate fashion via sulfur atom whereas diphosphine ligands coordinated as a bidentate mode to afford a square planner around the Pd(II) ion or tetrahedral around the Cd(II) ion. Except for complexes [Cd(PAC-dtc)₂(dppe)] and [Cd(PAC-dtc)₂(PPh₃)₂], the prepared complexes showed significant antimicrobial activity when evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Moreover, DFT calculations were performed to investigate three complexes {[Pd(PAC-dtc)₂(dppe)](1), [Cd(PAC-dtc)₂(dppe)](2), [Cd(PAC-dtc)₂(PPh₃)₂](7)}, and their quantum parameters were evaluated using the Gaussian 09 program at the B3LYP/Lanl2dz theoretical level. The optimized structures of the three complexes were square planar and tetrahedral geometry. The calculated bond lengths and bond angles showed a slightly distorted tetrahedral geometry for [Cd(PAC-dtc)₂(dppe)](2) compared to [Cd(PAC-dtc)₂(PPh₃)₂](7) due to the ring constrain in the dppe ligand. Moreover, the [Pd(PAC-dtc)₂(dppe)](1) complex showed higher stability compared to Cd(2) and Cd(7) complexes which can be attributed to the higher back-donation of Pd(1) complex.

Synthesis, structure, properties, and cytotoxicity of a (quinoline)RuCp+ complex

A rare example of a structurally characterized metal quinoline complex was prepared using a non-covalent quinoline-based proteasome inhibitor (Quin1), and a related complex bearing an inactive quinoline ligand (Quin2) was also synthesized. The quinolines are prepared by a one-pot procedure involving titanium-catalyzed alkyne iminoamination and are bound to ruthenium by reaction with CpRu(NCMe)₃⁺ PF₆^- in CH₂Cl₂. The arene of the quinoline is η⁶-bonded to the ruthenium metal center. The kinetics of quinoline displacement were investigated, and reactivity with deuterated solvents follows the order acetonitrile > DMSO > water. Quinolines with more methyl groups on the arene are more kinetically stable, and RuCp(Quin1)⁺ PF₆^- (1), which has two methyl groups on the arene, is stable for days in DMSO. In contrast, a very similar complex (2) made with Quin2 having no methyl groups on the arene was readily displaced by DMSO. Both 1 and 2 are stable in 9 : 1 water/DMSO for days with no measurable displacement of the quinoline. The cytotoxicity of the quinolines, their CpRu⁺-complexes, and CpRu(DMSO)₃⁺ PF₆^- was investigated towards two multiple myeloma cell lines: MC/CAR and RPMI 8226. To determine whether the activity of the complexes was related to the nature of the quinoline ligands, two structurally similar quinoline ligands with vastly different biological properties were investigated. Quin1 is a cytotoxic proteasome inhibitor, whereas Quin2 is not a proteasome inhibitor and showed no discernable cytotoxicity. The ruthenium complexes showed poor cellular proteasome inhibition. However, both 1 and 2 showed good cytotoxicity towards RPMI 8226 and MC/CAR, with 1 being slightly more cytotoxic. For example, 1 has a CC₅₀ = 2 μM in RPMI 8226, and 2 has a CC₅₀ = 5 μM for the same cell line. In contrast, CpRu(DMSO)₃⁺ PF₆^- was quite active towards MC/CAR with CC₅₀ = 2.8 μM but showed no discernible cytotoxicity toward RPMI 8226. The mechanism of action responsible for the observed cytotoxicity is not known, but the new Ru(Cp)(Quin)⁺ PF₆^- complexes do not cross-link DNA as found for platinum-based drugs. It is concluded that the Ru(Cp)(Quin)⁺ PF₆^- complexes remain intact in the cellular assays and constitute a new class of cytotoxic metal complexes.

Antagonist Impact of Selenium-Based Nanoparticles Against Mycobacterium tuberculosis

One of the cardinal causes of global deaths from a single-point infectious agent has been reported to be tuberculosis (or TB). At present times, the incidence of TB cases occurs mostly due to multi-drug resistance, which is expected to boost further in the upcoming times. Accordingly, the development of alternative treatment methodologies has received significant research interest. In this regard, the application of nanoparticles has notable cognizance. The literature suggested that nanoparticles have substantial potential to be used as the delivery medium for drug injection as well as they also serve as a potential bactericidal agent. In this present study, the efficacy of the selenium nanoparticles against the inhibition of growth of Mycobacterium tuberculosis was evaluated. The obtained results indicated that the synthesized selenium nanoparticles have notable cognizance towards the inhibition of growth of Mycobacterium tuberculosis by disrupting the integrity of their cell envelope. This study thus proposes a novel approach and opens new dimensional avenues in the field of nanoparticle-induced cell disruption strategies.

RUNAT-BI: A Ruthenium(III) Complex as a Selective Anti-Tumor Drug Candidate against Highly Aggressive Cancer Cell Lines

Ruthenium compounds have demonstrated promising activity in different cancer types, overcoming several limitations of platinum-based drugs, yet their global structure-activity is still under debate. We analyzed the activity of Runat-BI, a racemic Ru(III) compound, and of one of its isomers in eight tumor cell lines of breast, colon and gastric cancer as well as in a non-tumoral control. Runat-BI was prepared with 2,2'-biimidazole and dissolved in polyethylene glycol. We performed assays of time- and dose-dependent viability, migration, proliferation, and expression of pro- and antiapoptotic genes. Moreover, we studied the growth rate and cell doubling time to correlate it with the apoptotic effect of Runat-BI. As a racemic mixture, Runat-BI caused a significant reduction in the viability and migration of three cancer cell lines from colon, gastric and breast cancer, all of which displayed fast proliferation rates. This compound also demonstrated selectivity between tumor and non-tumor lines and increased proapoptotic gene expression. However, the isolated isomer did not show any effect. Racemic Runat-BI is a potential drug candidate for treatment of highly aggressive tumors. Further studies should be addressed at evaluating the role of the other isomer, for a more precise understanding of its antitumoral potential and mechanism of action.

The Versatility in the Applications of Dithiocarbamates

Dithiocarbamate ligands have the ability to form stable complexes with transition metals, and this chelating ability has been utilized in numerous applications. The complexes have also been used to synthesize other useful compounds. Here, the up-to-date applications of dithiocarbamate ligands and complexes are extensively discussed. Some of these are their use as enzyme inhibitor and treatment of HIV and other diseases. The application as anticancer, antimicrobial, medical imaging and anti-inflammatory agents is examined. Moreover, the application in the industry as vulcanization accelerator, froth flotation collector, antifouling, coatings, lubricant additives and sensors is discussed. The various ways in which they have been employed in synthesis of other compounds are highlighted. Finally, the agricultural uses and remediation of heavy metals via dithiocarbamate compounds are comprehensively discussed.

Oxidative DNA cleavage mediated by a new unexpected [Pd(BAPP)][PdCl4] complex (BAPP = 1,4-bis(3-aminopropyl)piperazine): crystal structure, DNA binding and cytotoxic behavior

A novel Pd(ii) double complex, [Pd(BAPP)][PdCl₄], containing the 1,4-bis(3-aminopropyl)piperazine (BAPP) ligand is investigated. X-ray crystallography of a single crystal confirmed the structure of the [Pd(BAPP)][PdCl₄] complex. The spectroscopic behavior was also elucidated using elemental analysis, nuclear magnetic resonance and Fourier-transform infrared spectroscopy, and mass spectrometry. The antimicrobial susceptibility of the [Pd(BAPP)][PdCl₄] complex against all tested microbial strains was lower than that of the BAPP ligand except for C. albicans. The cytotoxic impacts of the BAPP ligand and its [Pd(BAPP)][PdCl₄] complex were evaluated in vitro for HepG2, CaCo-2 and MCF7 cell lines as well as the WI-38 normal cell line. The anticancer activity was markedly improved by the complexation. The [Pd(BAPP)][PdCl₄] complex could selectively inhibit the tested cancer cells in a safe way to the non-tumorigenic cell (WI-38). From the DNA binding studies with ultraviolet-visible spectrophotometry, the [Pd(BAPP)][PdCl₄] complex interacts more efficiently with the calf thymus DNA than its BAPP ligand through the intercalative binding mode. In the absence of an external reductant, the [Pd(BAPP)][PdCl₄] complex cleaved the intact supercoiled pBR322 DNA under physiological conditions in a concentration-dependent manner. Additionally, electrophoretic experiments were performed in the presence of different radical scavengers, namely DMSO, NaN₃ and KI, and ruled out the hydrolytic mechanistic pathway of the reaction and suggested that the oxidative mechanism is the preferred one. The results of the binding affinity of the [Pd(BAPP)][PdCl₄] complex to human DNA were modeled using a molecular docking study showing that the complex interacts more strongly with human DNA than the ligand. Finally, an in vitro pharmacokinetic study was assessed through in silico ADME predictions.

Ruthenium(ii) complex containing cinnamic acid derivative inhibits cell cycle progression at G0/G1 and induces apoptosis in melanoma cells

Melanoma is a highly aggressive skin cancer with a limited targeted therapy arsenal.