Search

Abstract: The reaction of oxythiamine chloride hydrochloride (HOxTCl·HCl) with ZnCl2, CdCl2 and HgCl2 in ethanol yielded the complexes [ZnCl3(HOxT)], [CdCl3(HOxT)] and [HgCl3(HOxT)]. In water, the reaction with CdCl2 afforded [CdCl2(OxT)], but reaction with ZnCl2 or HgCl2 yielded unidentified products. The four new complexes were characterized by mass spectrometry and IR spectroscopy in the solid state and by 1H, 13C and 15N nuclear magnetic resonance (NMR) spectroscopy in hexadeuterated dimethylsulfoxide (DMSO-d 6), and three were also studied by X-ray diffractometry. In [ZnCl3(HOxT)] and [HgCl3(HOxT)] the oxythiamine ligand is bound to the metal via N(1′) and adopts the V conformation exhibited by thiamine in biological contexts. The infrared (IR) spectrum of [CdCl3(HOxT)] suggests a similar coordination mode. In [CdCl2(OxT)] each OxT zwitterion coordinates to one Cd(II) ion via its N(1′) atom and to another via its N(3′) and O atoms, giving rise to a polymeric chain along the x-axis. The coordination number of the metal is made up to six by Cd⋯Cl interactions, two of which link the polymeric chains in pairs. This seems to be the first metal complex containing the oxythiamine ligand as a zwitterion, with the N(3′)–H/O(4′α)–H group deprotonated. Neither HOxTCl nor its zinc(II) complex showed any significant activity in vitro against HeLa cells. [Copyright &y& Elsevier]

Abstract: Reaction of the vitamin K3 derivative menadione sodium bisulfite thiosemicarbazone (NaK3TSC) with chloro(triethylphosphine)gold(I) afforded the complex [AuPEt3(K3TSC)]. This compound consists of discrete molecules in which the metal is almost linearly coordinated to P and S. Preliminary in vitro screening showed significant anti-cancer activity, notably against the cisplatin-resistant cell line A2780cis. [Copyright &y& Elsevier]

Abstract: In this work we report on the synthesis, crystal structure, and physicochemical characterization of the novel dinuclear [FeIIICdII(L)(μ-OAc)2]ClO4·0.5H2O (1) complex containing the unsymmetrical ligand H2L=2-bis[{(2-pyridyl-methyl)-aminomethyl}-6-{(2-hydroxy-benzyl)-(2-pyridyl-methyl)}-aminomethyl]-4-methylphenol. Also, with this ligand, the tetranuclear [Fe2 IIIHg2 II(L)2(OH)2](ClO4)2·2CH3OH (2) and [FeIIIHgII(L)(μ-CO3)FeIIIHgII(L)](ClO4)2·H2O (3) complexes were synthesized and fully characterized. It is demonstrated that the precursor [FeIII 2HgII 2(L)2(OH)2](ClO4)2·2CH3OH (2) can be converted to (3) by the fixation of atmospheric CO2 since the crystal structure of the tetranuclear organometallic complex [FeIIIHgII(L)(μ-CO3)FeIIIHgII(L)](ClO4)2·H2O (3) with an unprecedented {FeIII(μ-Ophenoxo)2(μ-CO3)FeIII} core was obtained through X-ray crystallography. In the reaction 2 → 3 a nucleophilic attack of a FeIII-bound hydroxo group on the CO2 molecule is proposed. In addition, it is also demonstrated that complex (3) can regenerate complex (2) in aqueous/MeOH/NaOH solution. Magnetochemical studies reveal that the FeIII centers in 3 are antiferromagnetically coupled (J =−7.2cm−1) and that the FeIII–OR–FeIII angle has no noticeable influence in the exchange coupling. Phosphatase-like activity studies in the hydrolysis of the model substrate bis(2,4-dinitrophenyl) phosphate (2,4-bdnpp) by 1 and 2 show Michaelis–Menten behavior with 1 being ~2.5 times more active than 2. In combination with k H/k D isotope effects, the kinetic studies suggest a mechanism in which a terminal FeIII-bound hydroxide is the hydrolysis-initiating nucleophilic catalyst for 1 and 2. Based on the crystal structures of 1 and 3, it is assumed that the relatively long FeIII…HgII distance could be responsible for the lower catalytic effectiveness of 2. [Copyright &y& Elsevier]

Abstract: The synthesis and characterization of ruthenium compounds of the type [RuCl2(NO)(dppp)(L)]PF6 [dppp=1,3-bis(diphenylphosphino)propane; L=pyridine, 4-methylpyridine, 4-phenylpyridine and dimethyl sulfoxide] are described. The complexes were characterized by elemental analysis, UV/Vis and infrared spectroscopy, cyclic voltammetry, and X-ray crystallography for the complexes with the pyridine and 4-methylpyridine ligands. In vitro evaluation of these nitrosyl complexes revealed cytotoxic activity from 7.1 to 19.0μM against the MDA-MB-231 breast tumor cells and showed that, in this case, they are more active than the reference metallodrug cisplatin. The 1,3-bis(diphenylphosphino)propane and the N-heterocyclic ligands alone failed to show cytotoxic activities at the concentrations tested (maximum concentration utilized=200μM). [Copyright &y& Elsevier]

Abstract: The reaction of cis-[RuCl2(dppb)(N–N)], dppb=1,4-bis(diphenylphosphino)butane, complexes with the ligand HSpymMe2, 4,6-dimethyl-2-mercaptopyrimidine, yielded the cationic complexes [Ru(SpymMe2)(dppb)(N–N)]PF6, N–N=bipy (1) and Me-bipy (2), bipy=2,2′-bipyridine and Me-bipy=4,4′-dimethyl-2,2′-bipyridine, which were characterized by spectroscopic and electrochemical techniques and X-ray crystallography and elemental analysis. Additionally, preliminary in vitro tests for antimycobacterial activity against Mycobacterium tuberculosis H37Rv ATCC 27264 and antitumor activity against the MDA-MB-231 human breast tumor cell line were carried out on the new complexes and also on the precursors cis-[RuCl2(dppb)(N–N)], N–N=bipy (3) and Me-bipy (4) and the free ligands dppb, bipy, Me-bipy and SpymMe2. The minimal inhibitory concentration (MIC) of compounds needed to kill 90% of mycobacterial cells and the IC50 values for the antitumor activity were determined. Compounds 1–4 exhibited good in vitro activity against M. tuberculosis, with MIC values ranging between 0.78 and 6.25μg/mL, compared to the free ligands (MIC of 25 to >50μg/mL) and the drugs used to treat tuberculosis. Complexes 1 and 2 also showed promising antitumor activity, with IC50 values of 0.46±0.02 and 0.43±0.08μM, respectively, against MDA-MB-231 breast tumor cells. [Copyright &y& Elsevier]

Abstract: Two Cu(II) complexes with cyanoguanidine (cnge) and o-phenanthroline, [Cu(o-phen)2(cnge)](NO3)2 ·2H2O (1) and [Cu(o-phen)(cnge)(H2O)(NO3)2] (2), have been synthesized using different experimental techniques and characterized by elemental analyses, FTIR, diffuse and UV–vis spectra and EPR and magnetic moment measurements techniques. The crystal structures of both complexes were solved by X-ray diffraction methods. Complex (1) crystallizes in the monoclinic space group C2/c with a =12.621(5), b =31.968(3), c =15.39(1)Å, β =111.68(4)°, and Z =8 and complex (2) in the monoclinic space group P21/n with a =10.245(1), b =13.923(2), c =12.391(2)Å, β =98.07(1)°, and Z =4. The environments of the copper(II) center are trigonal bipyramidal (TBP) for [Cu(o-phen)2(cnge)]2+ and an elongated octahedron for [Cu(o-phen)(cnge)(H2O)(NO3)2]. Solution studies have been performed to determine the species distribution. The superoxide dismutase (SOD) activities of both complexes have also been tested in order to determine if these compounds mimic the enzymatic action of the enzyme SOD that protects cells against peroxide radicals. [Copyright &y& Elsevier]

Abstract: As a contribution to the development of novel vanadium complexes with pharmacologically interesting moieties, new dioxovanadium(V) semicarbazone complexes with the formula cis-VO2L, where L=5-bromosalicylaldehyde semicarbazone and 2-hydroxynaphtalen-1-carboxaldehyde semicarbazone have been synthesized and characterized by 1H and 13C NMR, Raman and FTIR spectroscopies. Results were compared with those previously reported for other three analogous complexes of this series. The five complexes were tested in three different human tumor cell lines for bioactivity as potential anti-tumor agents, showing selective cytotoxicity on TK-10 cell line. Results showed that structural modifications on the semicarbazone moiety could have a significant effect on the anti-tumor activity of the vanadium complexes. In addition, the electrochemical behavior of all the complexes was studied. No apparent correlation could be demonstrated between reduction potentials of the complexes and their anti-tumor activities. The molecular structure of the novel [VVO2(5-bromosalicylaldehyde semicarbazone)] complex was solved by X-ray diffraction methods. The vanadium atom shows a distorted square pyramidal coordination sphere. The (VO2)+ cation is coordinated to a nearly planar (L)− anion acting as a tridentate ligand through both oxygen and one nitrogen atoms. [Copyright &y& Elsevier]

The [RuII(Hedta)NO+] complex is a diamagnetic species crystallizing in a distorted octahedral geometry, with the Ru–N(O) length 1.756(4) Å and the RuNO angle 172.3(4)°. The complex contains one protonated carboxylate (pKa=2.7±0.1). The [RuII(Hedta)NO+] complex undergoes a nitrosyl-centered one-electron reduction (chemical or electrochemical), with ENO+/NO=−0.31 V vs SCE (I=0.2 M, pH 1), yielding [RuII(Hedta)NO]−, which aquates slowly: k–NO=2.1±0.4×10−3 s−1 (pH 1.0, I=0.2 M, CF3COOH/NaCF3COO, 25 °C). At pHs>12, the predominant species, [RuII(edta)NO]−, reacts according to [RuII(edta)NO]−+2OH−⇒[RuII(edta)NO2]3−, with Keq=1.0±0.4×103 M−2 (I=1.0 M, NaCl; T=25.0±0.1 °C). The rate-law is first order in each of the reactants for most reaction conditions, with kOH−=4.35±0.02 M−1s−1 (25.0 °C), assignable mechanistically to the elementary step comprising the attack of one OH− on [RuII(edta)NO]−, with subsequent fast deprotonation of the [RuII(edta)NO2H]2− intermediate. The activation parameters were ΔH#=60±1 kJ/mol, ΔS#=−31±3 J/Kmol, consistent with a nucleophilic addition process between likely charged ions. In the toxicity up-and-down tests performed with Swiss mice, no death was observed in all the doses administered (3–9.08×10−5 mol/kg). The biodistribution tests performed with Wistar male rats showed metal in the liver, kidney, urine and plasma. Eight hours after the injection no metal was detected in the samples. The vasodilator effect of [RuII(edta)NO]− was studied in aortic rings without endothelium, and was compared with sodium nitroprusside (SNP). The times of maximal effects of [RuII(edta)NO]− and SNP were 2 h and 12 min, respectively, suggesting that [RuII(edta)NO]− releases NO slowly to the medium in comparison with SNP. [Copyright &y& Elsevier]

As a contribution to the development of novel vanadium complexes with pharmacologically interesting moieties, new dioxovanadium(V) semicarbazone complexes with the formula cis-VO(2)L, where L=5-bromosalicylaldehyde semicarbazone and 2-hydroxynaphtalen-1-carboxaldehyde semicarbazone have been synthesized and characterized by (1)H and (13)C NMR, Raman and FTIR spectroscopies. Results were compared with those previously reported for other three analogous complexes of this series. The five complexes were tested in three different human tumor cell lines for bioactivity as potential anti-tumor agents, showing selective cytotoxicity on TK-10 cell line. Results showed that structural modifications on the semicarbazone moiety could have a significant effect on the anti-tumor activity of the vanadium complexes. In addition, the electrochemical behavior of all the complexes was studied. No apparent correlation could be demonstrated between reduction potentials of the complexes and their anti-tumor activities. The molecular structure of the novel [V(V)O(2)(5-bromosalicylaldehyde semicarbazone)] complex was solved by X-ray diffraction methods. The vanadium atom shows a distorted square pyramidal coordination sphere. The (VO(2))(+) cation is coordinated to a nearly planar (L)(-) anion acting as a tridentate ligand through both oxygen and one nitrogen atoms.