Sobre uma degenerescência acidental nos deslocamentos químicos de RMN de 31P{¹H} em complexos difosfínicos de rutênio

Synthesis, characterization and in vitro cytotoxicity of ruthenium(II) metronidazole complexes: Cell cycle arrest at G1/S transition and apoptosis induction in MCF-7 cells

Ruthenium compounds are known to be potential drug candidates since they offer the potential for reduced toxicity. Furthermore, the various oxidation states, different mechanisms of action and ligand substitution kinetics give them advantages over platinum-based complexes, making them suitable for use in biological applications. So, herein, novel ruthenium(II) complexes with metronidazole as ligand were obtained [RuCl(MTNZ)(dppb)(4,4'-Mebipy)]PF₆ (1), [RuCl(MTNZ)(dppb)(4,4'-Methoxybipy)]PF₆ (2), [RuCl(MTNZ)(dppb)(bipy)]PF₆ (3) and [RuCl(MTNZ)(dppb)(phen)]PF₆ (4) where, MTNZ = metronidazole, dppb = 1,4-bis(diphenylphosphino)butane, 4,4'-Mebipy = 4,4'-dimethyl-2,2'-bipyridine, 4,4'-Methoxybipy = 4,4'-dimethoxy-2,2'-bipyridine, bipy = 2,2'-bipyridine and phen = 1,10-phenanthroline. The complexes were characterized by elemental analysis, molar conductivity, infrared and UV-Vis spectroscopy, cyclic voltammetry, ³¹P{¹H}, ¹H, ¹³C{¹H} and Dept 135 NMR and mass spectrometry. The interaction of complexes 1-4 with DNA was evaluated, and their cytotoxicity profiles were determined on four different tumor cell lines derived from human cancers (SK-MEL-147, melanoma; HepG2, hepatocarcinoma; MCF-7, estrogen-positive breast cancer; A549, non-small cell lung cancer). We demonstrated that complexes (1) and (3) are promising antitumor agents once inhibited the proliferative behavior of MCF-7 cells and induced apoptosis.

Electrochemical, mechanistic, and DFT studies of amine derived diphosphines containing Ru(II)-cymene complexes with potent in vitro cytotoxic activity against HeLa and triple-negative breast cancer cells MDA-MB-231

Complexes with general formula [RuCl(η6-p-cymene)(P-NR-P)]X (R = CH2Py (Py = pyridine) - [1a]+, CH2Ph (Ph = phenyl) - [1b]+, Ph - [1c] and p-tol (p-tol = p-tolyl) - [1d]+; X = PF6- or BF4-) were evaluated as cytotoxic agents against two cancer cell lines (HeLa and MDA-MB-231). All metal complexes are active in the range of concentrations tested (up to 100 μmol L-1). The IC50 (μmol L-1) values for the metal complexes are lower than that found for cisplatin. The activities are up to 6- and 15-fold higher than cisplatin for HeLa and MDA-MB-231 cancer cell lines, respectively. Studies of DNA binding and DNA cleavage were performed. DNA binding studies revealed a modest hypochromic shift in the metal complexes electronic spectra, indicating a weak interaction with Kb values in the range of 1.7 × 103-1.6 × 104. Although the cleavage tests revealed that in the dark DNA is not a biological target for these metal complexes, upon blue light irradiation they are activated causing DNA cleavage. Electrochemical studies showed the presence of two independent redox processes, one attributed to the oxidation process of Ru2+ → Ru3+ (EC process) and the other one to the reduction of Ru2+ → Ru1+, which is further reduced to Ru0 (ECE mechanism). In both processes, coupled chemical reactions were observed. DFT calculations were performed to support the electrochemical/chemical behavior of the complexes. The reactivity of complex [1b]BF4 with CH3CN was evaluated and two complexes were isolated [2b]BF4 and [3b]BF4. The complex mer-[RuCl(CH3CN)3(P-NCH2Ph-P)]BF4 ([2b]BF4) was isolated after refluxing the precursor [1b]BF4 in CH3CN. Isomerization of [2b]BF4 in CH3CN resulted in the formation of fac-[RuCl(CH3CN)3(P-NCH2Ph-P)]BF4. An attempt to isolate the fac-isomer by adding diethyl ether was unsuccessful, and the complex [3b]BF4 was observed as the major component. The complex [Ru2(μ-Cl3)(CH3CN)2(P-NCH2Ph-P)2]BF4 ([3b]BF4) proved to be very stable and can be obtained from both the mer- and the fac-isomers. The molecular structures of [1b]BF4 and [3b]BF4 were solved by single-crystal X-ray diffraction.

In vitro cytotoxicity and in vivo zebrafish toxicity evaluation of Ru(ii)/2-mercaptopyrimidine complexes

In this paper, four new ruthenium complexes, [Ru(N-S)(dppm)2]PF6 (1), [Ru(N-S)(dppe)2]PF6 (2), [Ru(N-S)2(dppp)] (3) and [Ru(N-S)2(PPh3)2] (4) [dppm = 1,1-bis(diphenylphosphino)methane, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, PPh3 = triphenylphosphine and N-S = 2-mercaptopyrimidine anion] were synthesized and characterized using spectroscopy techniques, molar conductance, elemental analysis, electrochemical techniques and X-ray diffraction. The DNA binding studies were investigated using voltammetry and spectroscopy techniques. The results show that all complexes exhibit a weak interaction with DNA. HSA interaction with the complexes was studied using fluorescence emission spectroscopy, where the results indicate a spontaneous interaction between the species by a static quenching mechanism. The cytotoxicity of the complexes was evaluated against A549, MDA-MB-231 and HaCat cells by MTT assay. Complexes (1) and (2), which are very active against triple negative MDA-MB-231, were subjected to further biological tests with this cell line. The cytotoxic activity triggered by the complexes was confirmed by clonogenic assay. Cell cycle analyses demonstrated marked anti-proliferative effects, especially at the G0/G1 and S phases. The morphological detection of apoptosis and necrosis - HO/PI and Annexin V-FITC/PI assay, elucidated that the type of cell death triggered by these complexes was probably by apoptosis. The in vivo toxicological assessment performed on zebrafish embryos revealed that complexes (1) and (2) did not present embryotoxic or toxic effects during embryonic and larval development showing that they are promising new prototypes of safer and more effective drugs for triple negative breast cancer treatment.

Remarkable Electronic Effect on the meso-Tetra(thienyl)porphyrins

Complexes derived from meso-tetra(thienyl)porphyrins (TThP) and meso-tetra(pyridyl)porphyrin (TPyP) containing peripheral ruthenium complexes with general formulas {TPyP[RuCl(dppb)(5,5'-Mebipy)]₄}(PF₆)₄, {TThP[RuCl(dppb)(5,5'-Mebipy)]₄}(PF₆)₄, and {TThP-me-[RuCl(dppb)(5,5'-Mebipy)]₄}(PF₆)₄ [5,5'-Mebipy = 5,5'-dimethyl-2,2'-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane] were synthesized and characterized by spectroscopy techniques (¹H- and ³¹P{¹H}-NMR, IR, UV/vis, fluorescence, and electron paramagnetic resonance (EPR)), cyclic voltammetry, coulometry, molar conductivity, and elemental analysis. Voltammetry and UV/vis studies demonstrated differentiated electronic properties for ruthenium appended with TThP and TThP-me when compared to ruthenium appended with TPyP. The UV/vis analysis for the ruthenium complex derived from TThP and TThP-me, as well as the Soret and Q bands, characteristics of porphyrins, showed a band at 700 nm referring to the Ru → S electronic transition, and porphyrin TThP-me showed another band at 475 nm from the Ru-N transition. The attribution of these bands was confirmed by spectroelectrochemical analysis. Cyclic voltammetry analysis for the ruthenium complex derived from TPyP exhibited only an electrochemical process with E_1/2 = 0.47 V assigned to the Ru(II)/Ru(III) redox pair (Fc/Fc⁺). On the other hand, two processes were observed for the ruthenium complexes derived from TThP and TThP-me, with E_1/2 around 0.17 and 0.47 V, which were attributed to the formation of a mixed valence tetranuclear species containing Ru(II) and Ru(III) ions, showing that the peripheral groups are not oxidized at the same potential. Fluorescence spectroscopic experiments show the existence of a mixed state of emission in the supramolecular porphyrin moieties. The results suggest the formation of Ru(II)-Ru(III) mixed valence complexes when oxidation potential was applied around 0.17 V in the {TThP[RuCl(dppb)(5,5'-Mebipy)]₄}(PF₆)₄ and {TThP-me-[RuCl(dppb)(5,5'-Mebipy)]₄}(PF₆)₄ species.

Novel piplartine-containing ruthenium complexes: synthesis, cell growth inhibition, apoptosis induction and ROS production on HCT116 cells

Piplartine (piperlongumine) is a plant-derived molecule that has been receiving intense interest due to its anticancer characteristics that target the oxidative stress. In the present paper, two novel piplartine-containing ruthenium complexes [Ru(piplartine)(dppf)(bipy)](PF₆)₂ (1) and [Ru(piplartine)(dppb)(bipy)](PF₆)₂ (2) were synthesized and investigated for their cellular and molecular responses on cancer cell lines. We found that both complexes are more potent than metal-free piplartine in a panel of cancer cell lines on monolayer cultures, as well in 3D model of cancer multicellular spheroids formed from human colon carcinoma HCT116 cells. Mechanistic studies uncovered that the complexes reduced the cell growth and caused phosphatidylserine externalization, internucleosomal DNA fragmentation, caspase-3 activation and loss of the mitochondrial transmembrane potential on HCT116 cells. Moreover, the pre-treatment with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, reduced the complexes-induced apoptosis, indicating cell death by apoptosis through caspase-dependent and mitochondrial intrinsic pathways. Treatment with the complexes also caused a marked increase in the production of reactive oxygen species (ROS), including hydrogen peroxide, superoxide anion and nitric oxide, and decreased reduced glutathione levels. Application of N-acetyl-cysteine, an antioxidant, reduced the ROS levels and apoptosis induced by the complexes, indicating activation of ROS-mediated apoptosis pathway. RNA transcripts of several genes, including gene related to the cell cycle, apoptosis and oxidative stress, were regulated under treatment. However, the complexes failed to induce DNA intercalation. In conclusion, the complexes are more potent than piplartine against different cancer cell lines and are able to induce caspase-dependent and mitochondrial intrinsic apoptosis on HCT116 cells by ROS-mediated pathway.