Kansuinine A Ameliorates Atherosclerosis and Human Aortic Endothelial Cell Apoptosis by Inhibiting Reactive Oxygen Species Production and Suppressing IKKβ/IκBα/NF-κB Signaling

Reactive oxygen species (ROS)-induced vascular endothelial cell apoptosis is strongly associated with atherosclerosis progression. Herein, we aimed to examine whether Kansuinine A (KA), extracted from Euphorbia kansui L., prevents atherosclerosis development in a mouse model and inhibits cell apoptosis through oxidative stress reduction. Atherosclerosis development was analyzed in apolipoprotein E-deficient (ApoE^−/−) mice fed a high-fat diet (HFD) using Oil Red O staining and H&E staining. Human aortic endothelial cells (HAECs) were treated with KA, followed by hydrogen peroxide (H₂O₂), to investigate the KA-mediated inhibition of ROS-induced oxidative stress and cell apoptosis. Oil Red O staining and H&E staining showed that atherosclerotic lesion size was significantly smaller in the aortic arch of ApoE^−/− mice in the HFD+KA group than that in the aortic arch of those in the HFD group. Further, KA (0.1–1.0 μM) blocked the H₂O₂-induced death of HAECs and ROS generation. The H₂O₂-mediated upregulation of phosphorylated IKKβ, phosphorylated IκBα, and phosphorylated NF-κB was suppressed by KA. KA also reduced the Bax/Bcl-2 ratio and cleaved caspase-3 expression, preventing H₂O₂-induced vascular endothelial cell apoptosis. Our results indicate that KA may protect against ROS-induced endothelial cell apoptosis and has considerable clinical potential in the prevention of atherosclerosis and cardiovascular diseases.     

Synthesis of 2-Acyloxycyclohexylsulfonamides and Evaluation on Their Fungicidal Activity

Eighteen N-substituted phenyl-2-acyloxycyclohexylsulfonamides (III) were designed and synthesized by the reaction of N-substituted phenyl-2-hydroxyl-cycloalkylsulfonamides (I, R¹) with acyl chloride (II, R²) in dichloromethane under the catalysis of TMEDA and molecular sieve. High fungicidal active compound N-(2,4,5-trichlorophenyl)-2-(2-ethoxyacetoxy) cyclohexylsulfonamide (III-18) was screened out. Mycelia growth assay against the Botrytis cinerea exhibited that EC₅₀ and EC₈₀ of compound III-18 were 4.17 and 17.15 μg mL⁻¹ respectively, which was better than the commercial fungicide procymidone (EC₅₀ = 4.46 μg mL⁻¹ and EC₈₀ = 35.02 μg mL⁻¹). For in vivo activity against B. cinerea in living leaf of cucumber, the control effect of compound III-18 was better than the fungicide cyprodinil. In addition, this new compound had broader fungicidal spectra than chlorothalonil.     

Copper(II) Complexes Containing Natural Flavonoid Pomiferin Show Considerable In Vitro Cytotoxicity and Anti-inflammatory Effects

A series of new heteroleptic copper(II) complexes of the composition [Cu(L)(bpy)]NO₃·2MeOH (1), [Cu(L)(dimebpy)]NO₃·2H₂O (2), [Cu(L)(phen)]NO₃·2MeOH (3), [Cu(L)(bphen)]NO₃·MeOH (4), [Cu(L)(dppz)]NO₃·MeOH (5) was prepared, where HL = 3-(3,4-dihydroxyphenyl)-5-hydroxy-8,8-dimethyl-6-(3-methylbut-2-ene-1-yl)-4H,8H-benzo[1,2-b:3,4-b′]dipyran-4-one, (pomiferin) and bpy = 2,2′-bipyridine, dimebpy = 4,4′-dimethyl-2,2′-bipyridine, phen = 1,10-phenanthroline, bphen = 4,7-diphenyl-1,10-phenanthroline, and dppz = dipyrido[3,2-a:2′,3′-c]phenazine. The complexes were characterized using elemental analysis, infrared and UV/Vis spectroscopies, mass spectrometry, thermal analysis and conductivity measurements. The in vitro cytotoxicity, screened against eight human cancer cell lines (breast adenocarcinoma (MCF-7), osteosarcoma (HOS), lung adenocarcinoma (A549), prostate adenocarcinoma (PC-3), ovarian carcinoma (A2780), cisplatin-resistant ovarian carcinoma (A2780R), colorectal adenocarcinoma (Caco-2) and monocytic leukemia (THP-1), revealed the complexes as effective antiproliferative agents, with the IC₅₀ values of 2.2–13.0 μM for the best performing complexes 3 and 5. All the complexes 1–5 showed the best activity against the A2780R cells (IC₅₀ = 2.2–6.6 μM), and moreover, the complexes demonstrated relatively low toxicity on healthy human hepatocytes, with IC₅₀ > 100 μM. The complexes were evaluated by the Annexin V/propidium iodide apoptosis assay, induction of cell cycle modifications in A2780 cells, production of reactive oxygen species (ROS), perturbation of mitochondrial membrane potential, inhibition of apoptosis and inflammation-related signaling pathways (NF-κB/AP-1 activity, NF-κB translocation, TNF-α secretion), and tested for nuclease mimicking activity. The obtained results revealed the corresponding complexes to be effective antiproliferative and anti-inflammatory agents.     

Hydrogen Bonds,Topologies, Energy Frameworks and Solubilities of Five Sorafenib Salts

Sorafenib (Sor) is an oral multi-kinase inhibitor, but its water solubility is very low. To improve its solubility, sorafenib hydrochloride hydrate, sorafenib hydrobromide and sorafenib hydrobromide hydrate were prepared in the mixed solvent of the corresponding acid solution, and tetrahydrofuran (THF). The crystal structures of sorafenib hydrochloride trihydrate (Sor·HCl.3H₂O), 4-(4-{3-[4-chloro-3-(trifluoro-methyl)phenyl]ureido}phenoxy)-2-(N-methylcarbamoyl) pyridinium hydrochloride trihydrate, C₂₁H₁₇ClF₃N₄O₃⁺·Cl⁻.3H₂O (I), sorafenib hydrochloride monohydrate (Sor·HCl.H₂O), C₂₁H₁₇ClF₃N₄O₃⁺·Cl⁻.H₂O (II), its solvated form (sorafenib hydrochloride monohydrate monotetrahydrofuran (Sor·HCl.H₂O.THF), C₂₁H₁₇ClF₃N₄O₃⁺·Cl⁻.H₂O.C₄H₈O (III)), sorafenib hydrobromide (Sor·HBr), 4-(4-{3-[4-chloro-3-(trifluoro-methyl)phenyl]ureido}phenoxy)-2-(N-methylcarbamoyl) pyridinium hydrobromide, C₂₁H₁₇ClF₃N₄O₃⁺·Br⁻ (IV) and sorafenib hydrobromide monohydrate (Sor·HBr.H₂O), C₂₁H₁₇ClF₃N₄O₃⁺·Br⁻.H₂O (V) were analysed. Their hydrogen bond systems and topologies were investigated. The results showed the distinct roles of water molecules in stabilizing their crystal structures. Moreover, (II) and (V) were isomorphous crystal structures with the same space group P2₁/n, and similar unit cell dimensions. The predicted morphologies of these forms based on the BFDH model matched well with experimental morphologies. The energy frameworks showed that (I), and (IV) might have better tabletability than (II) and (V). Moreover, the solubility and dissolution rate data exhibited an improvement in the solubility of these salts compared with the free drug.     

FeIII,CuII and ZnII Complexes of the Rigid 9-Oxido-phenalenone Ligand—Spectroscopy,Electrochemistry, and Cytotoxic Properties

The three complexes [Fe(opo)₃], [Cu(opo)₂], and [Zn(opo)₂] containing the non-innocent anionic ligand opo⁻ (opo⁻ = 9-oxido-phenalenone, Hopo = 9-hydroxyphenalonone) were synthesised from the corresponding acetylacetonates. [Zn(opo)₂] was characterised using ¹H nuclear magnetic resonance (NMR) spectroscopy, the paramagnetic [Fe(opo)₃] and [Cu(opo)₂] by electron paramagnetic resonance (EPR) spectroscopy. While the EPR spectra of [Cu(opo)₂] and [Cu(acac)₂] in dimethylformamide (DMF) solution are very similar, a rather narrow spectrum was observed for [Fe(opo)₃] in tetrahydrofuran (THF) solution in contrast to the very broad spectrum of [Fe(acac)₃] in THF (Hacac = acetylacetone, 2,4-pentanedione; acac⁻ = acetylacetonate). The narrow, completely isotropic signal of [Fe(opo)₃] disagrees with a metal-centred S = 5/2 spin system that is observed in the solid state. We assume spin-delocalisation to the opo ligand in the sense of an opo⁻ to Fe^III electron transfer. All compounds show several electrochemical opo-centred reduction waves in the range of −1 to −3 V vs. the ferrocene/ferrocenium couple. However, for Cu^II and Fe^III the very first one-electron reductions are metal-centred. Electronic absorption in the UV to vis range are due to π–π* transitions in the opo core, giving Hopo and [Zn(opo)₂] a yellow to orange colour. The structured bands ranging from 400 to 500 for all compounds are assigned to the lowest energy π−π* transitions. They show markedly higher intensities and slight shifts for the Cu^II (brown) and Fe^III (red) complexes and we assume admixing metal contributions (MLCT for Cu^II, LMCT for Fe^III). For both complexes long-wavelength absorptions assignable to d–d transitions were detected. Detailed spectroelectrochemical experiments confirm both the electrochemical and the optical assignments. Hopo and the complexes [Cu(opo)₂], [Zn(opo)₂], and [Fe(opo)₃] show antiproliferative activities against HT-29 (colon cancer) and MCF-7 (breast cancer) cell lines in the range of a few µM, comparable to cisplatin under the same conditions.     

A novel Keggin-type tungstogermanate dimer bearing dinuclear copper-organic coordination ions: {H8[Cu(phen)(μ2-CH3COO)2Cu(phen)(H2O)]2[Ge2W23CuO80]} · 24H2O

An unprecedented Keggin-type tungstogermanate dimer bearing dinuclear copper-organic coordination ions {H₈[Cu(phen)(μ₂-CH₃COO)₂Cu(phen)(H₂O)]₂[Ge₂W₂₃CuO₈₀]} · 24H₂O has been synthesized and characterized by IR, UV, ICP analyses, ESR spectra, element analysis, TG and single crystal X-ray diffraction analysis. The compound is built up from a dimeric heteropolyanion constituted by two corner-shared Keggin-type building subunits and two dinuclear copper-organic coordination cations [Cu(phen)(μ₂-CH₃COO)₂Cu(phen)(H₂O)]²⁺, each of which consists two square pyramidal copper-phen ions bridged by two μ₂-acetate ligands.     

Aluminum-doped ceria-zirconia solid solutions with enhanced thermal stability and high oxygen storage capacity

A facile solvothermal method to synthesize aluminum-doped ceria-zirconia (Ce_0.5Zr_0.5-xAl_xO_2-x/2, x = 0.1 to 0.4) solid solutions was carried out using Ce(NH₄)₂(NO₃)₆, Zr(NO₃)₃·2H₂O Al(NO₃)₃·9H₂O, and NH₄OH as the starting materials at 200°C for 24 h. The obtained solid solutions from the solvothermal reaction were calcined at 1,000°C for 20 h in air atmosphere to evaluate the thermal stability. The synthesized Ce_0.5Zr_0.3Al_0.2O_1.9 particle was characterized for the oxygen storage capacity (OSC) in automotive catalysis. For the characterization, X-ray diffraction, transmission electron microscopy, and the Brunauer-Emmet-Teller (BET) technique were employed. The OSC values of all samples were measured at 600°C using thermogravimetric-differential thermal analysis. Ce_0.5Zr_0.3Al_0.2O_1.9 solid solutions calcined at 1,000°C for 20 h with a BET surface area of 18 m² g⁻¹ exhibited a considerably high OSC of 427 μmol-O g⁻¹ and good OSC performance stability. The same synthesis route was employed for the preparation of the CeO₂ and Ce_0.5Zr_0.5O₂. The incorporation of aluminum ion in the lattice of ceria-based catalyst greatly enhanced the thermal stability and OSC.     

In Vitro Activity of Copper(II) Complexes,Loaded or Unloaded into a Nanostructured Lipid System,against Mycobacterium tuberculosis

Tuberculosis (TB) is an infectious disease caused mainly by the bacillus Mycobacterium tuberculosis (Mtb), presenting 9.5 million new cases and 1.5 million deaths in 2014. The aim of this study was to evaluate a nanostructured lipid system (NLS) composed of 10% phase oil (cholesterol), 10% surfactant (soy phosphatidylcholine, sodium oleate), and Eumulgin^® HRE 40 ([castor oil polyoxyl-40-hydrogenated] in a proportion of 3:6:8), and an 80% aqueous phase (phosphate buffer pH = 7.4) as a tactic to enhance the in vitro anti-Mtb activity of the copper(II) complexes [CuCl₂(INH)₂]·H₂O (1), [Cu(NCS)₂(INH)₂]·5H₂O (2) and [Cu(NCO)₂(INH)₂]·4H₂O (3). The Cu(II) complex-loaded NLS displayed sizes ranging from 169.5 ± 0.7095 to 211.1 ± 0.8963 nm, polydispersity index (PDI) varying from 0.135 ± 0.0130 to 0.236 ± 0.00100, and zeta potential ranging from −0.00690 ± 0.0896 to −8.43 ± 1.63 mV. Rheological analysis showed that the formulations behave as non-Newtonian fluids of the pseudoplastic and viscoelastic type. Antimycobacterial activities of the free complexes and NLS-loaded complexes against Mtb H₃₇Rv ATCC 27294 were evaluated by the REMA methodology, and the selectivity index (SI) was calculated using the cytotoxicity index (IC₅₀) against Vero (ATCC^® CCL-81), J774A.1 (ATCC^® TIB-67), and MRC-5 (ATCC^® CCL-171) cell lines. The data suggest that the incorporation of the complexes into NLS improved the inhibitory action against Mtb by 52-, 27-, and 4.7-fold and the SI values by 173-, 43-, and 7-fold for the compounds 1, 2 and 3, respectively. The incorporation of the complexes 1, 2 and 3 into the NLS also resulted in a significant decrease of toxicity towards an alternative model (Artemia salina L.). These findings suggest that the NLS may be considered as a platform for incorporation of metallic complexes aimed at the treatment of TB.     

Ferromagnetic coupling in a novel dicyanamide-bridged dinuclear gadolinium(III) complex [Gd2(dca)4(OH)2 (NITpPy)4] (NITpPy = 4-pyridyl-nitronyl nitroxide radical)

The novel six-coordinated gadolinium(III) complex of formula [Gd₂(dca)₄(OH)₂(NITpPy)₄] (1) (dca = dicyanamide, NITpPy = 4-pyridyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-oxy-3-oxide) has been prepared and characterized by X-ray crystallography. Compound 1 is a dimer structure made up of double μ_1,5-dca-bridged gadolinium(III) ions and one terminal dca ligand; variable-temperature magnetic susceptibility measurements reveal the occurrence of a significant ferromagnetic interaction directly spin polarization through the NITpPy–Gd(III)–NITpPy pathway with J = 11.56 cm⁻¹.     

Synthesis, structure and magnetism of a μ3-carbonato bridged nickel(II) complex with 2,2′,2″-tris(2-aminoethyl)amine ligand: a new coordination mode of carbonato bridge

A novel bridged Ni(II) complex with tris(2-aminoethyl)amine (tren), [Ni₃(tren)₃(H₂O)₂(μ₃-CO₃)](ClO₄)₄ · 2H₂O, was obtained by bubbling CO₂ into an aqueous solution of μ₂-OH bridged Ni(II) complex. The X-ray structure analysis of the title complex shows that the three nickel atoms are asymmetrically bridged by one tetradentate carbonato ligand, which presents a new bridge mode. The further magnetochemistry study exhibits a strong antiferromagnetic coupling between nickel(II) ions with J₁ = −11.03 cm⁻¹, J₂ = −80.27 cm⁻¹ in the title compound.     

A new 3D supramolecular compound containing 1D chains and 1D water chains

The first crystal structure involving the discrete unsubstituted 1,2,4-triazolate anion is reported. In the title compound, [Na₂(H₂O)₈]_n(trz)_2n [trz = 1,2,4-triazolate] (1), each sodium(I) ion is coordinated by six water molecules with a slight distorted octahedron geometry. Each Na(I) are bridged by two μ₂-aqua ligands and arranged in an alternating fashion to construct a 1D zigzag {[Na₂(H₂O)₈]²⁺}_n chain. The 3D supermolecular framework is formed with 1D {[Na₂(H₂O)₈]²⁺}_n chain as the assembly units, by 1D water chain and 1,2,4-triazolate anion as the hydrogen bonding spacers.     

Synthesis, structure and magnetic properties of the first copper(II) complex with an (E)-4-aryl-4-oxo-2-butenoato ligand

A new binuclear Cu(II) complex with an (E)-4-(2,4-diisopropylphenyl)-4-oxo-2-butenoato ligand (L) was successfully synthesized and characterized by elemental analysis and IR-spectroscopy. The structures of (E)-4-(2,4-diisopropylphenyl)-4-oxo-2-butenoic acid (HL), and the corresponding (tetrakis)-μ-[(E)-4-(2,4-diisopropylphenyl)-4-oxo-2-butenoato]-bis(ethanol)-copper(II) complex, [Cu₂L₄(C₂H₅OH)₂], were determined by single crystal X-ray analyses and are preliminarily discussed. This is the first complex of a transition metal with ligand L, as well as the first determined crystal structure of a metal complex with this type of ligand. Analysis of the magnetic susceptibility measurements of the isolated [Cu₂L₄(C₂H₅OH)₂] · H₂O complex shows the existence of a strong anti-ferromagnetic intradimer coupling, with an exchange integral value 2J of −260 cm⁻¹.     

Comparison of resistive switching characteristics using copper and aluminum electrodes on GeOx/W cross-point memories

Comparison of resistive switching memory characteristics using copper (Cu) and aluminum (Al) electrodes on GeO_x/W cross-points has been reported under low current compliances (CCs) of 1 nA to 50 μA. The cross-point memory devices are observed by high-resolution transmission electron microscopy (HRTEM). Improved memory characteristics are observed for the Cu/GeO_x/W structures as compared to the Al/GeO_x/W cross-points owing to AlO_x formation at the Al/GeO_x interface. The RESET current increases with the increase of the CCs varying from 1 nA to 50 μA for the Cu electrode devices, while the RESET current is high (>1 mA) and independent of CCs varying from 1 nA to 500 μA for the Al electrode devices. An extra formation voltage is needed for the Al/GeO_x/W devices, while a low operation voltage of ±2 V is needed for the Cu/GeO_x/W cross-point devices. Repeatable bipolar resistive switching characteristics of the Cu/GeO_x/W cross-point memory devices are observed with CC varying from 1 nA to 50 μA, and unipolar resistive switching is observed with CC >100 μA. High resistance ratios of 10² to 10⁴ for the bipolar mode (CCs of 1 nA to 50 μA) and approximately 10⁸ for the unipolar mode are obtained for the Cu/GeO_x/W cross-points. In addition, repeatable switching cycles and data retention of 10³ s are observed under a low current of 1 nA for future low-power, high-density, nonvolatile, nanoscale memory applications.     

Structural Diversity of Copper(II) Complexes with 9-Deazahypoxanthine and Their in Vitro SOD-Like Activity

Two structurally different copper(II) complexes of the compositions [{Cu(9dhx)(H₂O)₃}₂(µ-SO₄)₂] (1) and [Cu(9dhx)₂(H₂O)₂(NO₃)₂]·H₂O (2), involving 9-deazahypoxanthine (9dhx; 6-oxo-9-deazapurine; 9-deazahypoxanthine), have been prepared and characterized by elemental analysis, infrared and electronic spectroscopy, electrospray ionisation (ESI) mass spectrometry, thermogravimetric (TG) and differential thermal (DTA) analyses, and cyclic voltammetry. The X-ray structures of complexes 1 and [Cu(9dhx)₂(H₂O)₂(NO₃)₂] (2a) revealed the distorted octahedral geometry in the vicinity of the copper(II) atoms, with the NO₅ and N₂O₄ donor set, respectively. In the dimeric compound 1, the {Cu(9dhx)(H₂O)₃}₂ units are bridged by sulfate groups with the Cu···Cu separation being 5.3446(2) Å. In both structures the 9dhx ligands are coordinated through the N3 atoms of the pyrimidine moieties. The SOD-like activity of complexes 1 and 2 was evaluated in vitro showing moderate effect, with the IC₅₀ values equal to 18.20, and 53.33 μM, respectively.     

Unique direct synthesis of cyanide-bridged Fe2Cu2 molecular squares by destruction of sodium nitroprusside

The one-pot reaction of copper powder, sodium nitroprusside, ammonium thiocyanate and 2,2′-bipyridine (bpy) in acetonitrile solution at ambient conditions of air and water yields the novel heterometallic [Fe₂Cu₂(bpy)₆(μ-CN)₄(NCS)₂]₂[Fe(CN)₅(NO)](NCS)₂·5H₂O complex 1, which has been structurally and magnetically characterized. The most prominent feature of this complex is the unique tetranuclear squares comprised [Cu(bpy)NCS]⁺ and [Fe(bpy)₂]²⁺ corners with CN edges. The CuCu and FeFe separations are 6.72 and 7.73 Å, respectively. The variable-temperature magnetic susceptibility study revealed that a very weak antiferromagnetic coupling is active between Cu(II) centers (J_CuCu = −0.37 cm⁻¹).     

A Halomanganates(II) with P,P’-Diprotonated Bis(2-Diphenylphosphinophenyl)ether: Wavelength-Excitation Dependence of the Quantum Yield and Role of the Non-Covalent Interactions

A [H₂DPEphos][MnX₄] [X = Br, Cl] tetrahalomanganates(II) with P,P’-diprotonated bis[2-(diphenylphosphino)phenyl]ether cation has been designed and investigated in photophysics and EPR terms. The complexes exhibit a green luminescence resulted from the Mn(II) d–d transitions (⁴T₁→⁶A₁) with the wavelength-excitation dependence of the quantum yield. The solid [H₂DPEphos][MnBr₄] complex exhibits a bright green phosphorescence (λ_max = 515 nm) with the high luminescence quantum yield depending on the excitation energy whereas the solid [H₂DPEphos][MnCl₄] complex exhibits a very weak phosphorescence (λ_max = 523 nm). The unexpected shorter luminescence lifetime for the [H₂DPEphos][MnCl₄] than for the [H₂DPEphos][MnBr₄] at 300 K can be a result of the higher non-radiative relaxation contribution. On the one hand, the non-covalent PH…X(Mn) interactions quench the manganese(II) luminescence. On the other hand, the PH…X(Mn) interactions are a pathway of the excitation transfer from [H₂DPEphos]²⁺ to [MnX₄]²⁻.     

Design of High-Relaxivity Polyelectrolyte Nanocapsules Based on Citrate Complexes of Gadolinium(III) of Unusual Composition

Through nuclear magnetic relaxation and pH-metry, the details of the complexation of gadolinium(III) ions with citric acid (H₄L) in water and aqueous solutions of cationic polyelectrolytes are established. It is shown that the presence of poly(ethylene imine) (PEI) in solution affects magnetic relaxation behavior of gadolinium(III) complexes with citric acid (Cit) to a greater extent than polydiallyldimethylammonium chloride (PDDC). A large increase in relaxivity (up to 50 mM⁻¹s⁻¹) in the broad pH range (4–8) is revealed for the gadolinium(III)–citric acid–PEI system, which is particularly strong in the case of PEI with the molecular weight of 25 and 60 kDa. In weakly acidic medium (pH 3–7), the presence of PEI results in the formation of two tris-ligand associates [Gd(H₂L)₃]³⁻ and [Gd(H₂L)₂(HL)]⁴⁻, which do not exist in aqueous medium. In weakly alkaline medium (pH 7–10), formation of ternary complexes Gd(III)–Cit–PEI with the Gd(III)–to–Cit ratio of 1:2 is evidenced. Using transmission electron microscopy (TEM) and dynamic light scattering techniques (DLS), the formation of the particles with the size of 50–100 nm possessing narrow molecular-mass distribution (PDI 0.08) is determined in the solution containing associate of PEI with tris-ligand complex [Gd(H₂L)₂(HL)]⁴⁻.     

A Comparative Analysis of the In Vitro Anticancer Activity of Iridium(III) {η5-C5Me4R} Complexes with Variable R Groups

Piano-stool iridium complexes based on the pentamethylcyclopentadienyl ligand (Cp*) have been intensively investigated as anticancer drug candidates and hold much promise in this setting. A systematic study aimed at outlining the effect of Cp* mono-derivatization on the antiproliferative activity is presented here. Thus, the dinuclear complexes [Ir(η⁵-C₅Me₄R)Cl(μ-Cl)]₂ (R = Me, 1a; R = H, 1b; R = Pr, 1c; R = 4-C₆H₄F, 1d; R = 4-C₆H₄OH, 1e), their 2-phenylpyridyl mononuclear derivatives [Ir(η⁵-C₅Me₄R)(k_N,k_CPhPy)Cl] (2a–d), and the dimethylsulfoxide complex [Ir{η⁵-C₅Me₄(4-C₆H₄OH)}Cl₂(κ_S-Me₂S=O)] (3) were synthesized, structurally characterized, and assessed for their cytotoxicity towards a panel of six human and rodent cancer cell lines (mouse melanoma, B16; rat glioma, C6; breast adenocarcinoma, MCF-7; colorectal carcinoma, SW620 and HCT116; ovarian carcinoma, A2780) and one primary, human fetal lung fibroblast cell line (MRC5). Complexes 2b (R = H) and 2d (4-C₆H₄F) emerged as the most active ones and were selected for further investigation. They did not affect the viability of primary mouse peritoneal cells, and their tumoricidal action arises from the combined influence on cellular proliferation, apoptosis and senescence. The latter is triggered by mitochondrial failure and production of reactive oxygen and nitrogen species.     

Hydrogen Sulfide Up-Regulates the Expression of ATP-Binding Cassette Transporter A1 via Promoting Nuclear Translocation of PPARα

ATP binding cassette transporter A1 (ABCA1) plays a key role in atherogenesis. Hydrogen sulfide (H₂S), a gasotransmitter, has been reported to play an anti-atherosclerotic role. However, the underlying mechanisms are largely unknown. In this study we examined whether and how H₂S regulates ABCA1 expression. The effect of H₂S on ABCA1 expression and lipid metabolism were assessed in vitro by cultured human hepatoma cell line HepG2, and in vivo by ApoE^−/− mice with a high-cholesterol diet. NaHS (an exogenous H₂S donor) treatment significantly increased the expression of ABCA1, ApoA1, and ApoA2 and ameliorated intracellular lipid accumulation in HepG2 cells. Depletion of the endogenous H₂S generator cystathionine γ-lyase (CSE) by small RNA interference (siRNA) significantly decreased the expression of ABCA1 and resulted in the accumulation of lipids in HepG2 cells. In vivo NaHS treatment significantly reduced the serum levels of total cholesterol (TC), triglycerides (TG), and low-density lipoproteins (LDL), diminished atherosclerotic plaque size, and increased hepatic ABCA1 expression in fat-fed ApoE^−/− mice. Further study revealed that NaHS upregulated ABCA1 expression by promoting peroxisome proliferator-activated receptor α (PPARα) nuclear translocation. H₂S up-regulates the expression of ABCA1 by promoting the nuclear translocation of PPARα, providing a fundamental mechanism for the anti-atherogenic activity of H₂S. H₂S may be a promising potential drug candidate for the treatment of atherosclerosis.     

Kinetics of ligand exchange reaction of Cu(II)-ammine complex with poly(vinyl alcohol) in aqueous solution

The kinetics of the ligand exchange reaction of the Cu(II)-ammine complex with poly(vinyl alcohol) (PVA) has been studied by a stopped-flow method at pH 9–10, at μ=0.1 (NH₄Cl) and at 25°C. The reaction is initiated by the formation of unstable [Cu(NH₃)₃]²⁺ by the attack of H⁺ on Cu(II)-ammine complex, and proceeds through the mixed complex {[Cu(NH₃)₃(O?PVA)]²⁺}. This step may be rate-determining, followed by a rapid reaction. Finally, the Cu(II) ion is taken up by PVA. The rate is given by d[Cu(II)?PVA]/dt=k[H⁺]{[Cu(NH₃)₄]²⁺}[PVA]/[NH₄Cl], where k=k₁ + k′₂[H⁺], k₁=4.25× 10s^?1 and k′₂=5.20× 10¹¹l mol^?1s^?1.