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At least 433 records · Page 24Linked to original sources
PubMed1997

Liquid-Crystalline Mono- and Dinuclear (Perhalophenyl)gold(I) Isocyanide Complexes.

Rodlike gold(I) and gold(III) complexes [AuR(C&tbd1;N(C(6)H(4))(m)()OC(n)()H(2)(n)()(+1)-p)] (m = 1, n = 10, R = C(6)F(5); m = 2, n = 4, 6, 8, 10, 12, R = C(6)F(5), C(6)F(4)Br-o, C(6)F(4)Br-p), [(&mgr;-4,4'-C(6)F(4)C(6)F(4)){AuC&tbd1;N(C(6)H(4))(m)()OC(n)()H(2)(n)()(+1)}(2)] (m = 1, 2; n = 4, 6, 8, 10, 12), [AuRI(2)(C&tbd1;NC(6)H(4)C(6)H(4)OC(n)()H(2)(n)()(+1)-p)] (R = C(6)F(5), n = 8; R = C(6)F(4)Br-o, n = 10), and [(&mgr;-4,4'-C(6)F(4)C(6)F(4)){AuX(2)C&tbd1;N(C(6)H(4))(m)()OC(n)()H(2)(n)()(+1)}(2)] (m = 1, 2; n = 4, 6, 8, 10, 12) have been prepared and their liquid crystal behavior has been studied. The gold(III) compounds are not mesomorphic, but all the perhalo-gold(I) derivatives described are liquid crystals except the phenyl isocyanide gold(I) derivative [Au(C(6)F(5))(C&tbd1;NC(6)H(4)OC(10)H(21)-p)]. The mononuclear derivatives show only a nematic (N) phase when the isocyanides have a short tail (n = 4), N and smectic A phases (S(A)) when the isocyanides have an intermediate tail (n = 6, 8), and only S(A) phases for longer chains. Their thermal stability is high, even in the isotropic state. The variation in transition temperatures is as follows: C(6)F(4)Br-p >/= C(6)F(5) > C(6)F(4)Br-o when n </= 6 and C(6)F(4)Br-p > C(6)F(4)Br-o > C(6)F(5) for n >/= 8. This behavior is understood on the basis of electronic and steric factors. The dinuclear compounds [(&mgr;-4,4'-C(6)F(4)C(6)F(4)){AuC&tbd1;N(C(6)H(4))(m)()OC(n)()H(2)(n)()(+1)}(2)] display only N mesophases and all the biphenylisocyanide derivatives and phenyl isocyanide compounds with n </= 6 undergo some decomposition upon reaching the clearing point to the isotropic state.

Journal Article↗
PubMed2006

Thioredoxin reductase and cancer cell growth inhibition by organogold(III) compounds.

Thioredoxin (Trx) expression is increased in several human primary cancers associated with aggressive tumor growth and decreased patient survival, and the Trx/Trx reductase (TrxR) system therefore provides an attractive target for cancer drug development. Various gold(III) compounds with none, one, two or three carbon-gold bonds were evaluated for their capacity to inhibit TrxR and the growth of MCF-7 cancer cells in vitro. Compounds with up to two carbon-gold bonds were often potent inhibitors of TrxR with IC50 values as low as 2 nmol/l. In the presence of Trx and insulin the inhibiting capacity was much lower. However, the inhibitory concentrations of the compounds did not correlate with the ability to kill cells. Out of the organometallics tested, only compound 8 with two carbon-gold bonds was able to inhibit colony formation by MCF-7 breast cancer cells at low micromolar concentrations (IC50=1.6 micromol/l). Unfortunately, the compound did not show any anti-tumor activity against MCF-7 breast cancer and HT-29 colon cancer xenografts in scid mice.

Animals↗
PubMed2006

Development of the Pictet-Spengler reaction catalyzed by AuCl3/AgOTf.

Mild and efficient AuCl3/AgOTf-catalyzed Pictet-Spengler reactions were developed to afford in good yields a variety of tetrahydroisoquinoline and tetrahydro-beta-carboline ring systems, which constitute important motifs in biologically active natural and synthetic organic compounds.

Carbolines↗
PubMed1996

Labeling with nanogold and undecagold: techniques and results.

A significant new development in gold labeling for microscopy has been achieved through the use of gold cluster compounds that are covalently attached to antibodies or other probe molecules. These unique gold probes are smaller than most colloidal gold conjugates and exhibit improved penetration into tissues, higher labeling densities, and allow many new probes to be made with peptides, nucleic acids, lipids, drugs, and other molecules. A new fluorescent-gold conjugate is useful for examining localization by fluorescence microscopy, then visualizing the same label at the ultrastructural level in the electron microscope.

Animals↗
PubMed2003

Enzyme-amplified electrochemical detection of DNA using electrocatalysis of ferrocenyl-tethered dendrimer.

We have developed a sandwich-type enzyme-linked DNA sensor as a new electrochemical method to detect DNA hybridization. A partially ferrocenyl-tethered poly(amidoamine) dendrimer (Fc-D) was used as an electrocatalyst to enhance the electronic signals of DNA detection as well as a building block to immobilize capture probes. Fc-D was immobilized on a carboxylic acid-terminated self-assembled monolayer (SAM) by covalent coupling of unreacted amine in Fc-D to the acid. Thiolated capture probe was attached to the remaining amine groups of Fc-D on the SAM via a bifunctional linker. The target DNA was hybridized with the capture probe, and an extension in the DNA of the target was then hybridized with a biotinylated detection probe. Avidin-conjugated alkaline phosphatase was bound to the detection probe and allowed to generate the electroactive label, p-aminophenol, from p-aminophenyl phosphate enzymatically. p-Aminophenol diffuses into the Fc-D layer and is then electrocatalytically oxidized by the electronic mediation of the immobilized Fc-D, which leads to a great enhancement in signal. Consequently, the amount of hybridized target can be estimated using the intensity of electrocatalytic current. This DNA sensor exhibits a detection limit of 20 fmol. Our method was also successfully applied to the sequence-selective discrimination between perfectly matched and single-base mismatched target oligonucleotides.

Alkaline Phosphatase↗
PubMed1982

Biospecific labeling with undecagold: visualization of the biotin-binding site on avidin.

The biotin-binding site on avidin has been labeled with biotin conjugated to undecagold, an organometallic cluster compound containing 11 gold atoms in a core angestroms in diameter. Examination of unstained specimens by scanning transmission electron microscopy reveals the labeled sites directly, without computational averaging or filtering of the images. This approach should be widely applicable for determining the locations of subunits and functional site in biological macromolecules at a resolution at a resolution in range of 15 angstroms.

Avidin↗
PubMed2002

Gold derivatives for the treatment of cancer.

The cytotoxicity and anti-tumour activity screening trials for both gold(I) and gold(III) are summarised. Gold(I) thiolates employed clinically in the treatment of rheumatoid arthritis display some potency against various tumours but a greater potential is found in their analogues. In particular, analogues featuring a linear P-Au-S arrangement in which the thiolate ligand is derived from a biologically active thiol display high potency. Further, targeting mitochondria with tetrahedrally coordinated gold(I) phosphine compounds with enhanced hydrophilicity is a research direction with exciting potential. Recent research has shown that gold(III) compounds featuring square-planar geometries, as found in cisplatin, may target DNA and may provide new anti-tumour agents.

Animals↗
PubMed2002

Gold(III) complexes as a new family of cytotoxic and antitumor agents.

In recent years, owing to the contributions of a few research groups, some new gold(III) compounds--either simple coordination complexes or organogold compounds--have been prepared that are sufficiently stable under physiological conditions and are promising candidates for pharmacological testing as cytotoxic and antitumor agents. In vitro pharmacological studies point out that some of these novel gold(III) complexes are highly cytotoxic toward cultured human tumor cell lines and are able to overcome resistance to platinum. Significant differences in the spectrum of action were observed compared with cisplatin. Studies are in progress to elucidate the mechanism of action of these compounds. The cellular effects of two representative gold(III) complexes are described. Preliminary results on binding to DNA in vitro are presented, pointing out that the interactions are generally weak. The implications of these results for the development of gold(III) complexes as a new family of cytotoxic and antitumor agents are discussed.

Antineoplastic Agents↗
PubMed1995

Inhibitory properties of triethylphosphine goldlupinylsulfide in adjuvant-induced arthritis in rats.

A new gold coordination compound (triethylphosphine goldlupinylsulfide: TP-Au-LS) was tested in adjuvant-induced arthritis in the rat, by oral administration at doses of 5, 10 and 20 mg/kg/day of gold for 17 consecutive days, in comparison with auranofin and betamethasone. TP-Au-LS produced a dose dependent reduction of both the injected and uninjected hind paw volume. Gold levels in serum (measured on day 18 by inductively coupled plasma atomic emission spectrometry) were also found to be dose related. At the dose of 10 mg/kg, TP-Au-LS and auranofin induced superimposable reductions of the injected paw volume; however the first drug produced higher serum gold concentrations than those achieved with the latter.

Animals↗
PubMed1987

Antitumor activity of bis(diphenylphosphino)alkanes, their gold(I) coordination complexes, and related compounds.

Bisphosphines related to bis(diphenylphosphino)ethane (dppe) and their gold complexes are described that are active in a spectrum of transplantable tumor models. When administered ip on days 1-5 at its maximally tolerated dose (MTD) of 40 mumol/kg, dppe reproducibly gives 100% increase in life span (ILS) in mice bearing ip P388 leukemia. Coordination of chlorogold(I) to each phosphine in dppe gave a complex that had similar activity but at a much lower dose level than dppe; the MTD for the gold(I) complex was 7 mumol/kg. Among other metal complexes of dppe, the Au(III) complex was active (greater than 50% ILS) whereas Ag(I), Ni(II), Pt(II), Pd(II), and Rh(I) complexes were inactive. Among dppe analogues, replacement of phenyl groups with ethyl or benzyl groups resulted in inactivity for both ligands and the corresponding gold complexes whereas substitution with cyclohexyl or heterocyclic ring systems yielded ligands and/or gold complexes with antitumor activity. Among substituted-phenyl dppe and dppe(AuCl)2 analogues, 3-fluoro, 4-fluoro, perdeuterio, 4-methylthio, and 2-methylthio analogues were active; 4-methyl, 3-methyl, 4-methoxy, 4-dimethylamino, and 4-trifluoromethyl analogues were marginal or inactive. Analogues in which the ethane bridge of dppe or dppe(AuCl)2 was varied between one and six carbons, unsaturated or substituted, revealed that activity was maximal with ethane or cis-ethylene. Compounds with good P388 activity were also active in other animal tumor models.

Animals↗
PubMed2005

Group 11 complexes with unsymmetrical P,S and P,Se disubstituted ferrocene ligands.

The reaction of the unsymmetrical ligands 1-diphenylphosphino-1'-(phenylsulfanyl)ferrocene and 1-diphenylphosphino-1'-(phenylselenyl)ferrocene, Fc(EPh)PPh2(E = S, Se), with several group 11 metal derivatives leads to the synthesis of complexes of the type [MX{Fc(EPh)PPh2}](M = Au, X = Cl, C6F5; M = Ag, X = OTf), (OTf = trifluoromethanesulfonate), [M{Fc(EPh)PPh2}2]X (M = Au, X = ClO4; M = Ag, X = OTf), [M(PPh3){Fc(EPh)PPh2}]OTf (M = Au, Ag), [Au2{Fc(SPh)PPh2}2](ClO4)2, [Au(C6F5)2{Fc(SePh)PPh2}]ClO4, [Au(C6F5)3{Fc(EPh)PPh2}], [Au2(C6F5)6{Fc(SePh)PPh2}] or [Cu{Fc(EPh)PPh2}2]PF6(E = S, Se). In these complexes coordination depends upon the metal centre; with gold it takes place predominantly to the phosphorus atom and with silver and copper to both phosphorus and chalcogen atoms. The treatment of some of the gold complexes with other metal centres affords heterometallic derivatives that in some cases are in equilibrium with the homometallic derivatives. Several compounds have been characterized by X-ray diffraction, four pairs of homologous compounds, yet not a single pair is isotypic. In many of them a three dimensional network is formed through secondary bonds such as hydrogen bonds, Au...Cl or Au...Se interactions. The complex [Ag(OTf){Fc(SePh)PPh2}] forms one-dimensional chains through trifluoromethanesulfonate bridging ligands.

Crystallography, X-Ray↗