388 research outputs found
Solution speciation and human serum protein binding of indium(III) complexes of 8-hydroxyquinoline, deferiprone and maltol
Antitumour Organometallics. III. In Vivo Activity of Diphenylantimony(III) and Diorganotin(IV) Dithiophosphorus Derivatives Against P388 Leukemia
Diphenylantimony(III) and diorganotin(IV) derivatives of dithiophosphorus ligands, i.e. Ph2SbS2PR′2 (R′ = Ph, OPr-i) and R2Sn(S2PR′2)2
(R = n-Bu, Ph, R′ = Ph; R = Ph, R′ = OPr-i),
have been screened against P388 leukemia in mice. All the compounds showed marginal activity
towards this tumor system, some of them increasing the life span of the animals with more than
20%. The best results were obtained with (di-iso-propylphosphorodithioato)diphenylantimony(III)
which exhibited a T/C value of 136%, at a dose of 5 mg/kg, administered on days 1,2 and 3 after
tumor transplantation
Solvolysis of the Tumor-Inhibiting Ru(III)-Complex trans-Tetrachlorobis(Indazole)Ruthenate(III)
The ruthenium(III) complex Hlnd trans-[RuCl4,(ind)2], with two trans-standing indazole (ind)
ligands bound to ruthenium via nitrogen, shows remarkable activity in different tumor models
in vitro and in vivo. The solvolysis of the complex trans-[RuCl4,(ind)2]- has been investigated by means of spectroscopic techniques (UV/vis, NMR)in different solvents. We investigated the
indazolium as well as the sodium salt, the latter showing improved solubility in water. In
aqueous acetonitrile and ethanol the solvolysis results in one main solvento complex. The
hydrolysis of the complex is more complicated and depends on the pH of the solution as well
as on the buffer system
The binding properties of two antitumor ruthenium(III) complexes to apotransferrin.
The interaction of two ruthenium(III) complexes exhibiting high anticancer activity, namely trans-indazolium(bisindazole)tetrachlororuthenate(III) (ru-ind) and trans-imidazolium(bisimidazole)tetrachlororuthenate(III) (ru-im), with human serum apotransferrin has been investigated through spectroscopic and chromatographic techniques with the ultimate goal of preparing adducts with good selectivity for cancer cells. Whereas the binding of ru-im to human serum apotransferrin takes several hours, ru-ind, the less toxic complex, gives rise to a well defined 2:1 complex within a few minutes. We have ascertained that ru-ind binding occurs around the iron binding sites; binding does not occur in the absence of bicarbonate, and this anion dictates the kinetic and mechanistic characteristics of protein binding of ru-ind. The two ruthenium(III) complexes do not behave as iron(III) complexes, e.g. Fe(EDTA) or Fe(nitrilotriacetate), which lose their respective ligands when binding apotransferrin, but the N-heterocycles remain attached to the metal in the protein-bound species. Reversion of binding is obtained by acidification in the presence of chelators such as citrate or ATP. In comparison with cisplatin and its deactivation by serum proteins, our results indicate that other metal complexes such as ru-ind could use transferrin as a drug delivery system. Furthermore, the rapid protein binding of ru-ind seems to be related to a lower toxicity while still exhibiting high antitumor activity
Synthesis, Characterization and Molecular Structures of some Bismuth(III) Complexes with Thiosemicarbazones and Dithiocarbazonic Acid Methylester Derivatives with Activity against Helicobacter Pylori
The reactions of bismuth(III) nitrate pentahydrate and bismuth(III) chloride with heterocyclic
thiosemicarbazones and derivatives of dithiocarbazonic acid methylester were used to synthesize
the respective bismuth(III) complexes, which could be divided into five groups D-H because
of their stoichiometrical properties and their molecular structures. The molecular
structure and the near coordination sphere of the bismuth(III) central atom of four representative
compounds were determined by single-crystal X-ray studies. Bis[1-azepanyl-4-(2-pyridyl)-2,3-diazapenta-1,3-diene-1-thiolato-N′,N3,S]bismuth(III) nitrate (5) belongs to group D. The
two tridentate ligands and the nitrate ion surround the bismuth atom. The best description of
the coordination sphere appears to be that of a distorted trigonal dodecahedron with one position
occupied by the lone pair of the bismuth atom. Bis[1-azepanyl-4-(2-thienyl)-2,3-diazapenta-1,3-diene-1-thiolato-N3,S]bismuth(III) nitrate (9) is assigned to complex type E.
Here, two deprotonated ligand molecules are coordinated to the bismuth(III) central atom as
bidentate ligands. The structure of this complex can best be described as a distorted trigonal
antiprism with a five-coordinated central atom. The two triangular faces are formed by the atoms
S(4), N(6), O(11) and S(3), N(4) and the lone pair of the central atom. The two chelate
rings are almost perpendicular to each other. Complex molecules of group F form dimeric
units with bichloro-bridged bismuth atoms. The structure of di-μ-chlorobis[1-azepanyl-4-(2-pyridyl)-2,3-diazapenta-1,3-diene-1-thiolato-N′,N3,S-chloro]dibismuth(III) (15) can be described
as two six-coordinated bismuth atoms, which are bound together via two bridging
chlorine atoms. The two bismuth atoms Bi(1) and Bi(1a) and the two bridging chlorine atoms
Cl(2) and Cl(2a) form the Bi2Cl2 plane. The two tridentate ligand molecules coordinate via the
same atoms as shown in complex 5. In addition, they form two parallel planes, which are perpendicular
to the Bi2Cl2 plane. With regard to the center of the Bi(1)-Bi(2) axis they are central
point symmetrical, i.e. one pyridine ring lies above and the other beneath the Bi2Cl2 plane. Bismuth(III) chloride and pyridine-2-carboxaldehydethiosemicarbazone 1 b or 2-acetylpyridine-thiosemicarbazone
1 c form complexes of group G. Three chlorine atoms and a bidentate ligand
are coordinated to the bismuth(III) central atom. The bidentate ligand bound to the
central atom through the N(3) atom and the sulfur atom of the thioketo group. The structure
of 18 is completely different from the structures of the bismuth(III) complexes discussed so
far and was therefore assigned to group H. The bismuth central atom is coordinated with two
ligands, which are bound in different ways. One of them is deprotonated. This ligand is bound
to the central atom via the sulfur atom S(3) of the thiolate group and the N(5) atom. An interaction
between the sulfur atom of the thiophene ring and the bismuth atom is not possible.The other ligand molecule is not deprotonated. This ligand is bound to the bismuth(III) cation
merely via the sulfur atom S(1) of the thioketo group. The best description of the coordination
sphere of the bismuth atom is that of a distorted square bipyramidal polyhedron. The square
face is formed by the atoms S(3), N(5), Cl(1), the lone pair and the bismuth atom within. The
axial positions are occupied by the atoms S(1) and Cl(2). The bond angle between S(1), Bi(1)
and Cl(2) differs by about eight degrees from the value determined for a regular square
bipyramidal polyhedron of 180 degrees
Synthesis, Characterization and Solution Chemistry of trans-Indazoliumtetrachlorobis(Indazole)Ruthenate(III), a New Anticancer Ruthenium Complex. IR, UV, NMR, HPLC Investigations and Antitumor Activity. Crystal Structures of trans-1-Methyl-Indazoliumtetrachlorobis-(1-Methylindazole)Ruthenate(III) and its Hydrolysis Product trans-Monoaquatrichlorobis-(1-Methylindazole)-Ruthenate(III)
Besides intensive studies into the synthesis of the complex trans-Hlnd[RuCl4(ind)2] (Ind = indazole)
1, which differs remarkably from the usual method for the complexes of the HL[RuCl4L2] - type,
competitive products and hydrolysis of this species are described. Stability and pseudo-first-order
rate constant under physiological conditions of complex 1 in comparison with the analogous imidazole
complex trans-Hlm[RuCl4im2] (Im = imidaZole) ICR were examined by means of HPLC, UV
and conductivity measurements (Kobs.(1) = 1.55 × 10-4 s-1; Kobs.(ICR) = 9.10 × 10-4 s-1). An attempt
was made to elucidate the bonding conditions in 1 by studying the reactions of Ru(lll) and the two
N-methyl isomers of indazole. It can be expected that bonding in the unsubstituted ligand should
occur via the N2 nitrogen. The molecular structures of the complex trans-H(1-Melnd)[RuCl4(1-Melnd)2] × 1H2O (1-Melnd = 1-methylindazole) 6 and its hydrolysis product in aqueous solution
[RuCl4(H2O)(1-Melnd)2]
7 were determined crystallographically. After anisotropic refinement of F
values by least squares, R is 0.053 for 6 and 0.059 for 7. Both complexes crystallize with four molecules in a unit cell of monoclinic symmetry. The space group is P2.1/n for 6 with cell dimensions
a = 10.511Å, b = 13.87Å, c = 19.93Å, and β = 98.17° and C2/c for 7 with a = 19.90Å, b = 10.94Å, c = 8.490Å and β = 96.74 ° The fact that the aqua species 7 could be isolated after dissolving
6 in a water/acetone solution confirmed the theory of many Ru(lll) complexes being initially
transformed, under physiological conditions, into aqua complexes in a first and often rate-determining
hydrolysis step. Compounds 1 and ICR are potent antitumor agents which exhibit activity
against a variety of tumor cells and experimental tumor models in animals, including autochthonous
colorectal tumors. Clinical studies with 1 are in preparation
Ruthenium versus platinum: interactions of anticancer metallodrugs with duplex oligonucleotides characterised by electrospray ionisation mass spectrometry
The binding of the ruthenium-based anticancer drug candidates KP1019, NAMI-A and RAPTA-T towards different double-stranded oligonucleotides was probed by electrospray ionisation mass spectrometry and compared with that of the widely used platinum-based chemotherapeutics cisplatin, carboplatin and oxaliplatin. It was found that the extent of adduct formation decreased in the following order: cisplatin>oxaliplatin>NAMI-A>RAPTA-T>carboplatin>KP1019. In addition to the characterisation of the adducts formed with the DNA models, the binding sites of the metallodrugs on the oligonucleotides were elucidated employing top-down tandem mass spectrometry and were found to be similar for all the metallodrugs studied, irrespective of the sequence of the oligonucleotide. A strong preference for guanine residues was establishe
Fragmentation methods on the balance: unambiguous top-down mass spectrometric characterization of oxaliplatin-ubiquitin binding sites
The interaction between oxaliplatin and the model protein ubiquitin (Ub) was investigated in a top-down approach by means of high-resolution electrospray ionization mass spectrometry (ESI-MS) using diverse tandem mass spectrometric (MS/MS) techniques, including collision-induced dissociation (CID), higher-energy C-trap dissociation (HCD), and electron transfer dissociation (ETD). To the best of our knowledge, this is the first time that metallodrug-protein adducts were analyzed for the metal-binding site by ETD-MS/MS, which outperformed both CID and HCD in terms of number of identified metallated peptide fragments in the mass spectra and the localization of the binding sites. Only ETD allowed the simultaneous and exact determination of Met1 and His68 residues as binding partners for oxaliplatin. CID-MS/MS experiments were carried out on orbitrap and ion cyclotron resonance (ICR)-FT mass spectrometers and both instruments yielded similar results with respect to number of metallated fragments and the localization of the binding sites. A comparison of the protein secondary structure with the intensities of peptide fragments generated by collisional activation of the [Ub + Pt-(chxn)] adduct [chxn = (1R,2R)-cyclohexanediamine] revealed a correlation with cleavages in solution phase random coil areas, indicating that the N-terminal β-hairpin and α-helix structures are retained in the gas phase. Figure CID, HCD and ETD were used to determine the binding site of the anticancer agent oxaliplatin on ubiquitin in a top-down approac
Synthesis and in vitro Antitumor Potency of (Cyclohexane-1,2-Diamine)Platinum(II) Complexes with Aminotris(Methylenephosphonic Acid) as Bone-Seeking Ligand
In order to develop platinum complexes with selective activity in primary and secondary bone
malignancies and with the aim to optimize antitumor activity, platinum(II) complexes with
aminotris(methylenephosphonic acid) as bone-seeking (osteotropic) ligand have been synthesized,
characterized and tested in the cisplatin-sensitive ovarian carcinoma cell line CH1. As non-leaving diamine
ligands, which are decisive for the cellular processing of DNA adducts, cis-R,S-cyclohexane-1,2-diamine,
trans-S,S-cyclohexane-1,2-diamine and trans-R,R-cyclohexane-1,2-diamine have been used, resulting in
complexes 1, 2, and 3, respectively. The cytotoxicity of the complexes under investigation decreases in the
order 3 > 2 > 1 which is in accord with structure-activity relationships with other (cyclohexane-1,2-
diamine)platinum(II) and platinum(IV) complexes: Both trans complexes (2 and 3) display a higher in vitro
potency than the corresponding cis isomer (I), with the trans-R,R isomer (3) being the most active in this
series. In comparison to the analogous (cyclohexane-1,2-diamine)platinum(II) complexes with
bis(phosphonomethyl)aminoacetic acid as osteotropic carrier ligand, the cytotoxicity of 1-3 was found to be
1.5 – 2 fold higher, which is explainable by a different coordination mode of the phosphonic acid ligands
(acetato versus phosphonato)
Planar Polymer Optical Waveguide with Metal-Organic Framework Coating for Carbon Dioxide Sensing
An easily fabricated gas sensor based on planar polymer optical waveguides with an integrated zeolite imidazole framework-8 (ZIF-8) thin film is presented for carbon dioxide detection and sensing. The planar optical waveguides are made of polymethylmethacrylate and fabricated by hot embossing, which makes it flexible and cost-efficient. Thin ZIF-8 films are uniformly grown on the waveguides surface through a simple solution method, which is crucial for the envisioned production of metal organic framework-based sensing devices on a large scale. Experimental results show that the produced optical elements exhibit a sensitivity of ≈2.5 μW/5 vol% toward carbon dioxide (CO2) with very rapid response time (≈6 s) and excellent reversibility of adsorption and desorption of the gas molecules. The demonstrated planar polymer sensing devices provide the potential to develop flexible on-chip gas sensors in an inexpensive and reproducible way
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