platinum(II) complexes

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Synthesis and characterization of a novel platinum (IV) complex from its platinum (II) analogue using molecular iodine as an oxidizing agent: an interesting synthetic route for the preparation of new platinum complexes.

Synthesis and characterization of a novel platinum (IV) complex from its platinum (II) analogue using molecular iodine as an oxidizing agent: an interesting synthetic route for the preparation of new platinum complexes.

SYNTHESIS AND CHARACTERIZATION OF A NOVEL PLATINUM (IV) COMPLEX FROM ITS PLATINUM (II) ANALOGUE USING MOLECULAR IODINE AS AN OXIDIZING AGENT: AN INTERESTING SYNTHETIC ROUTE FOR THE PREPARATION OF NEW PLATINUM COMPLEXES. In an attempt to reduce toxicity and widen the spectrum of activity of cisplatin and its analogues, much attention has been focused on designing new platinum complexes. This work reports the synthesis and characterization of novel compounds of the platinum (II) and platinum (IV) containing 2-furoic hydrazide acid and iodide as ligands. Although the prepared compounds do not present the classical structure of biologically active platinum analogues, they could be potentially active or useful as precursors to prepare antitumor platinum complexes. The reported compounds were characterized by 1 H NMR, 13 C
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Platinum complexes in cancer chemotherapy.

Platinum complexes in cancer chemotherapy.

A progressiva redução observada no ângulo entre as bases consecutivas como função do acréscimo da quantidade de cis-DDP ligado, mostra que o principal modo de interação, ligação cruzada [r]

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Syntheses, crystal structure and spectroscopic characterization of new platinum(II) dithiocarbimato complexes

Syntheses, crystal structure and spectroscopic characterization of new platinum(II) dithiocarbimato complexes

The syntheses of the platinum complexes were performed according to Scheme 1. Potassium tetrachloroplatinate(II) (0.001 mol) and tetrabutylammonium bromide (0.002 mol) were added to a solution of potassium N-R-sulfonyldithiocarbimate dihydrate (1 or 2, 0.002 mol) in methanol/water 1:1 (10 mL). The reaction mixture was stirred for 3 h at room temperature. The yel- low solid obtained was filtered, washed with distilled water and dried under reduced pressure for one day, yielding (Bu 4 N) 2 [Pt(N-

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J. Braz. Chem. Soc.  vol.21 número10

J. Braz. Chem. Soc. vol.21 número10

Antitumor platinum(II) complexes derived from N-alkyl-propanediamine differing in the length of their carbon chain (C8, C10, C12 and C14) were incorporated in liposomes and the cytotoxic activity of these formulations was evaluated against tumor (A 549 , MDA-MB-231, B16-F1 and B16-F10) and non-tumor (BHK-21 and CHO) cell lines. Stable and monodisperse liposome suspensions incorporating the platinum complexes were obtained from the lipid composition consisting of distearoyl-sn-glycero-3-phosphocholine, cholesterol and 1,2-distearoyl-sn-glycero- 3-phophoethanolamine-N-(methoxy(polyethylene glycol)-2000) at 5:3:0.3 molar ratio. The entrapment eficiency (EE%) of the platinum complexes in liposomes increased with the carbon chain length. EE% was higher than 80% in C12- and C14-derivatives. The effect of liposome encapsulation on the cytotoxic activity of the complexes was found to depend on the carbon chain length. These data indicate that the highest drug bioavailability from liposome formulations was achieved with the complex showing intermediate carbon chain length and partition between the liposome membrane and aqueous phase.
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J. Braz. Chem. Soc.  vol.24 número11

J. Braz. Chem. Soc. vol.24 número11

possibility of studying a platinum(II) complex in which the ligands are PZA molecules began being explored recently from an experimental point of view by the group coordinated by Professor Nicolás A. Rey at Pontifícia Universidade Católica do Rio de Janeiro (Rio de Janeiro, Brazil), with theoretical support given by our group (NEQC) at Universidade Federal de Juiz de Fora (Minas Gerais, Brazil). This proposal attempts to link the best of two different classes of compounds: the lesser toxic effects of pyrazinamide with the large antitumoral spectrum of activity of platinum complexes, based on the well-established concept of hybrid drugs (see as example the work of Guddneppanavar et al. 19 ).
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Synthesis and reactivity of triphenylstibine-platinum complexes: a bibliographic revision.

Synthesis and reactivity of triphenylstibine-platinum complexes: a bibliographic revision.

Ainda é importante considerar o fato de que nos estudos de compostos com ER 3 (E = P, As; R = Ph) como ligantes ancilares no átomo central de platina, estes ligantes podem conter outros[r]

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J. Braz. Chem. Soc.  vol.28 número5

J. Braz. Chem. Soc. vol.28 número5

could be released prematurely before reaching its target. Thus, the use of SPIONs coated with dextran modified with platinum(II) complexes may circumvent this problem. In this work we report the use of two new strategies (Scheme 1) to attach platinum complexes onto the surface of 6 nm SPIONs (M6): (i) by coating the SPIONs with platinum(II) complex functionalized dextran (DexPt1-2) and (ii) by direct coordination of a carboxylate platinum(IV) complex (PD) for comparison. Furthermore, the colloidal properties of these nanosystems (M6@CA@DexPt1-2 and M6@PD) have been evaluated in aqueous and PBS buffer media. These studies are essential to comprehend their behavior, especially with respect to aggregation and surface charge, which will dictate their future applications.
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Quím. Nova  vol.25 número4

Quím. Nova vol.25 número4

SYNTHESIS AND CHARACTERIZATION OF OXOVANADIUM (IV) DITHIOCARBAMATES WITH PYRIDINE We report the synthesis and study of a new series of oxovanadium (IV) dithiocarbamate adducts and derivatives with pyridine and cyclohexyl, di-iso-butyl, di-n-propyl, anilin, morpholin, piperidin and di-iso-propyl amines. The complexes have been characterized by analytical, magnetochemical, IR, visible-UV spectral and thermal studies, and are assigned the formulas [VO(L) 2 ].py, where

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Eclet. Quím.  vol.33 número1

Eclet. Quím. vol.33 número1

It is clear from the values of stability con- stants of complexes that sulfadiazine formed the complexes of minimum stability as its complexes showed the lowest values of E 1/2 in comparison to the other sulfonamide complexes [23]. The sta- bility constants of sulfisoxazole complexes are lesser than sulfamethoxazole complexes is due to the presence of two electron withdrawing CH 3 groups in former than in the latter caused greater steric hindrance [24] in sulfisoxazole complexes than sulfamethoxazole complexes. Similar is the case with sulfamethazine and sulfathiazole com- plexes. In case of sulfactamide and sulfanilamide, the former is the N 1 – acetyl-substituted deriva-
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Protein-protein docking with F(2)Dock 2.0 and GB-rerank.

Protein-protein docking with F(2)Dock 2.0 and GB-rerank.

2.8.1 Automated detection of complex types. Since F 2 Dock 2.0’s parameters are optimized separately for antibody- antigens and enzyme-inhibitors/enzyme-substrates, and a general set of parameters are used for all other types of complexes, the user only needs to specify the complex type to ensure the set of optimized parameters are applied. If the type is unknown, F 2 Dock 2.0 tries to determine which set of parameters to use as follows. If F 2 Dock 2.0 locates the six CDR loops (L1, L2, L3, H1, H2 and H3) in the protein sequence using the algorithm in [49], it identifies it as an antibody and uses the corresponding parameter set. Otherwise, if neither molecule is identified as an antibody and at least one of the molecules has at least 200 residues and at least 8% of its surface residues are Glycines then F 2 Dock 2.0 uses the enzyme complex parameter set. Finally, if both tests fail, a set of parameters for the general case is used. Among the complexes in the Zlab benchmark 2.0, F 2 Dock 2.0 fails to identify only one antibody (1KXQ) and three enzymes (1AY7, 1UDI and 2MTA). See Supplement S1 for details.
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Respiratory chain complexes in dynamic mitochondria display a patchy distribution in life cells.

Respiratory chain complexes in dynamic mitochondria display a patchy distribution in life cells.

We next asked whether the distribution pattern was dependent on the respective RC complexes and ATP synthase combination in the experiment. It is conceivable that complexes usually found in supercomplexes like CI, CII and CIV would display a different mixing behavior then CII or CV, which are not part of these macromolecular arrangements. To complete the analysis, all possible red-green labelled RC complex pairs were investigated. First, the patterned distribution of RC complexes and ATP synthase proved to be reproducible in all recently fused mitochondria (Figure 5I and J, fusion). Due to the rather high sample standard deviations, a distinct mixing behaviour of different RC complexes could not be deduced with certainty. This variance has several causes: i) depending on the position in the polykaryon the hybrid mitochondria underwent already more or less fusion/fission cycles, and ii) the number of cells participating in the formation of the polykaryon has some influence on the hybridisation and mixing speed. So, a standardisation is rather difficult for this kind of experiment. For each combination of DsRed and EGFP-labelled RC complexes, at least 3 independent PEG-induced fusion or co-expression assays were performed. In hetero-combinations such as CI and CIII both possible fusion/coexpression combinations, namely CI-G x CIII-R and CI-R x CIII-G were performed. In every experiment, 4–5 polykaryons were examined and at least 5 single mitochondria underwent co-localization analysis.
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Copper II - polar amino acid complexes: toxicity to bacteria and larvae of Aedes aegypti

Copper II - polar amino acid complexes: toxicity to bacteria and larvae of Aedes aegypti

Mortality data for Ae. aegypti were used to estimate the lethal concentration 50% (LC 50 ) and 99% (LC 99 ) for the larval population. The calculation of LCs was performed using the Probit analysis (StatPlus Software 2009). LCs were expressed in milligrams per liter (mg L -1 ). Estimates of variation of LC 50 and LC 99 between the complexes were compared by analysis of variance (Kruskal-Wallis H) and Mann-Whitney tests. In the analysis of variance, the results of bioassays tested the null hypothesis, that the estimated LC 50 and LC 99 of each complex were equal, against the alternative hypothesis that at least one of the means for each parameter was different, establishing the significance level of 5%.
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Implante contemporâneo de stents convencionais: comparação dos stents de hastes finas de aço inoxidável versus cromo-cobalto.

Implante contemporâneo de stents convencionais: comparação dos stents de hastes finas de aço inoxidável versus cromo-cobalto.

A adição de novos componentes químicos ao stent metálico, como a platina (platinum enhanced stainless steel - PERSS), aumentando a radiopacidade e a resistência dos stents de aço inoxidável e reduzin- do a possibilidade de fadiga do material e o risco de fratura das hastes, bem como o desenvolvimento da nanotecnologia, produzindo materiais mais homogê- neos e com menos impurezas, são algumas das novi- dades que certamente serão incorporadas em breve à Cardiologia Intervencionista, podendo melhorar ainda mais o desempenho dos stents tanto convencionais como farmacológicos.

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J. Braz. Chem. Soc.  vol.15 número5

J. Braz. Chem. Soc. vol.15 número5

In the morphological analysis, typical crystals of β-CD were found in many different sizes (Figure 1A). BBAP showed a wavy domain by SEM (Figure 1B) and an amorphous one by X-ray diffraction. There was an agglomeration of β-CD around the BBAP in the physical mixtures of BBAP/ β-CD 1:1 (Figure 2A) and 1:2 (Figure 3A). Regarding the co- evaporated inclusion complex BBAP/ β-CD 1:1 (Figure 2B) and 1:2 (Figure 3B), a compact structure formed by the aggregation of the crystals was observed. Whereas the physical mixture showed the crystalline structure of BBAP and β-CD, the features of both crystals in the inclusion complex were not easily detectable. Scanning electron microscopy revealed morphological differences among the different preparations, contributing to the characterization of the physical mixtures and of the inclusion complexes BBAP/β-CD 1:1 and 1:2. These data are in agreement with previous results, 7 showing the presence of inclusion complex
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J. Braz. Chem. Soc.  vol.21 número7

J. Braz. Chem. Soc. vol.21 número7

The addition of the compounds 1 and 2 quenches the luorescence emission with different afinities (Figure 5). The effects of free tc and dox are not very strong: to displace 50% of Eb from DNA sites it is necessary to add a molar ratio drug-to-Eb equal to 289 for dox and 106 for tc. Therefore, to attain the same quenching it is necessary to add approximately 2.7 times more doxycycline than tetracycline to the solution. By comparing the results obtained with the proligands to those with their respective Pt II complexes, one

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Protein Connectivity in Chemotaxis Receptor Complexes.

Protein Connectivity in Chemotaxis Receptor Complexes.

and lattice structures with the seemingly contradictory FRET results. By implementing the linker structure we initially fit our model of receptor complexes of up to four TDs to FRET data obtained with cells that express only the Tar receptor in different non-adapting modifica- tion states. Next, we apply our model to Tar–Tsr–Tap and Tsr–only cells in the non-adapting QEQE modification state, which mimics half-methylated receptors. As a result we recover the experimentally observed decrease in cooperativity of the response to serine with increasing CheA concentration, whereas increasing CheW yields the observed enhanced cooperativity. Note, other higher order effects of protein overexpression, such as membrane invaginations or interference of CheA/ CheW with clustering, are not included. Our results surmise that the observed opposing trends in cooperativity are based on a critical combination of the correct linker architecture and a constant average complex size.
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Widespread cotranslational formation of protein complexes.

Widespread cotranslational formation of protein complexes.

polysomes, it allows the identification of mRNAs cotranslationally associated with the bait protein. Using this technique we recently showed that the Rng3p myosin-specific chaperone associates cotranslationally with all five myosin heavy chains in the fission yeast Schizosaccharomyces pombe [6]. Another study in the budding yeast Saccharomyces cerevisiae found that the SET1 mRNA is part of a complex containing four components of the SET1C histone methyltransferase complex. The protein-RNA interactions were dependent on active translation, suggesting that the complex between these proteins was formed cotranslationally [7]. Apart from these few examples, very little is known about the prevalence of cotranslational assembly in the formation of protein complexes. Importantly, systematic approaches to identify and characterise this phenomenon (such as RIp-chip) have not been applied to large numbers of proteins.
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Live imaging of Xwnt5A-ROR2 complexes.

Live imaging of Xwnt5A-ROR2 complexes.

into these clusters formed by Xwnt5A-EGFP. A Wnt5A-depen- dent clustering of ROR2 was recently demonstrated by Feike et al. [24], who incubated Xenopus animal cap tissue with Wnt5A- conditioned medium. Our results show that ROR2 and Wnt5A co-localize in these clusters. Together with the observation that Wnt5A activates the ATF2-Luc reporter only in a short-range manner, this might suggest a model in which Wnt5A sticks and clusters at the surface of the Wnt producing cell. These clusters recruit ROR2 and stay as ligand/receptor complexes at the membrane. To analyze the ROR2/Wnt5A complexes inside the clusters in more detail, the STED-RICS method [25], which has been applied recently to bright spots on plasma membranes of cultured cells, will be adapted to analyze Xenopus tissue in the future.
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Study of electrocrystallization of Ni and Ni-P on platinum ultramicroelectrode.

Study of electrocrystallization of Ni and Ni-P on platinum ultramicroelectrode.

STUDY OF ELECTROCRYSTALLIZATION OF Ni AND Ni-P ON PLATINUM ULTRAMICROELECTRODE. This work describes a comparative study of the electrocrystallization of Ni and Ni-P on Pt ultramicroelectrodes using chronoamperometric measurements. It was possible to confirm that in all cases a progressive nucleation was the predominant mechanism. Moreover, the application of the Atomistic Theory to the experimental rate of nuclei formation showed that the number of atoms in the critical nucleus was zero, except for Ni-P on Pt at low overpotentials were a value of one was observed. Furthermore, the physical characterisation of the different deposits on Pt by atomic force microscopy allowed observing the coalescence of the hemispherical nuclei of Ni and Ni-P at t max thus confirming the results obtained from the current-time analysis.
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Evaluation of the cytotoxicity of transition metal complexes: DNA cleavage of copper complexes in cells

Evaluation of the cytotoxicity of transition metal complexes: DNA cleavage of copper complexes in cells

EtBr, a weak fluorescent when it is alone, is one of a most widely used dye to probe nucleic acids [100]. Upon binding to DNA, by intercalation between DNA base pairs, the fluorescence intensity of EtBr intensifies allowing the detection of the DNA-EtBr emission [57]. Substances acting as fluorescence quenchers, which is the case for some copper complexes, could decrease the fluorescence of EtBr-DNA in process known as quenching [58]. However, quenchers do not necessarily bind to DNA by intercalation. Groove binding or electrostatic interaction can be sufficient enough to decrease the emission intensity of EtBr-nucleic acid complex by releasing EtBr [50]. Fluorescence-based EtBr displacement assay has been performed to study the potential interaction between ct-DNA and copper complex, [Cu(L)Cl]CH 3 OH. The
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