Search results for "polyamines"
showing 10 items of 89 documents
Polyamines containing naphthyl groups as pH-regulated molecular machines driven by light
2001
A series of compounds made up by linking methylnaphthalene fragments at both ends of different polyamine chains have shown to behave as pH-regulated molecular machines driven by light and fluorescence emission studies have proved the formation of an excimer between the two naphthalene units whose appearance, fluorescence intensity and decay times depend on the pH value of the media. Albelda Gimeno, Maria Teresa, Teresa.Albelda@uv.es ; Garcia-España Monsonis, Enrique, Enrique.Garcia-Es@uv.es ; Soriano Soto, Concepción, Concepcion.Soriano@uv.es
CO2 Fixation by Cu2+ and Zn2+ complexes of a terpyridinophane aza receptor. Crystal structures of Cu2+ complexes, pH-metric, spectroscopic, and elect…
2006
The synthesis of the terpyridinophane-type polyamine 2,6,9,12,16-pentaaza[17]-(5,5' ')-cyclo-(2,2':6',2' ')-terpyridinophane heptahydrobromide tetrahydrate (L.7HBr.4H2O) is described. L presents six protonation constants with values in the range 9.21-3.27 logarithmic units. L interacts with Cu2+ and Zn2+ forming in both cases, neutral, protonated, and hydroxylated mono- and binuclear complexes whose constants have been calculated by potentiometry in 0.15 M NaClO4 at 298.1 K. The crystal structures of the compounds [Cu(HL-carb)(H2O)](ClO4)3.2H2O (1) and [Cu2(H2L)(CO3)]2(ClO4)8.9H2O (2) have been solved by X-ray diffraction. In 1, the metal center presents square pyramidal geometry. The base …
Electrochemical impedance spectroscopy of polyelectrolyte multilayer modified gold electrodes: influence of supporting electrolyte and temperature.
2005
Electrochemical impedance spectroscopy and cyclic voltammetry are employed to characterize poly(styrenesulfonate)/poly(allylamine hydrochloride) multilayers assembled onto cysteamine-modified gold surfaces. The influence of the supporting electrolyte and temperature on the impedance response is studied because of both its practical interest and the need to test further the capillary membrane model recently developed by Barreira et al. [J. Phys. Chem. B 2004, 108, 17973]. The results obtained are interpreted quite satisfactorily in terms of this model, thus providing additional support to its usefulness for the description of ionic transport through polyelectrolyte multilayers. It is observe…
Polyamines and applications. A look at the first workshop in linear and cyclic polyamines chemistry
2008
Given their versatile coordination properties, cyclic and linear polyamines are the subject of numerous worksin many research groups. This great interest is mainly related to their use in diverse fields such as removalof metals from liquids, purification of gases, application in catalysis, in sensors, as well as in various probesfor medical applications. This paper summarizes recent results obtained by the French research groupswhich attended the first ìworkshop in linear and cyclic polyamines chemistryî.
Pattern of polyamines and related monoacetyl derivatives in chick embryo retina during development.
1994
Polyamines and related monoacetyl derivatives were studied in chick embryo retina during development (6th-19th day). Putrescine, which is high in the first phase of retinogenesis, is necessary to sustain both tissue proliferation and via N-acetylputrescine, gamma-aminobutyric acid synthesis. A later increase in spermidine and particularly spermine may play a role in the last phase of development when the retina reaches maturation. The presence of N1-acetylspermidine already at the 8th day indicates that in chick embryo retina, putrescine synthesis can depend on two separate pathways. The first involves ornithine decarboxylase activity; the second, spermidine/spermine N1-acetyltransferase an…
Free and conjugated polyamine content in Citrus sinensis Osbeck, cultivar Brasiliano N.L.92, a Navel orange, at different maturation stages
2004
Biogenic amines, synthesized during physiological metabolic processes of all living organisms, are present in food. At low concentrations, polyamines are essential for cell renewal and growth, but they can be detrimental when consumed in high amount through the diet as they could support abnormal cell growth pathologies. The daily human diet contains more putrescine than spermidine or spermine, mostly derived from fruits. In general, orange fruits contain high levels of put, a fact that could limit their utilization in the daily diet besides the benefits contributed by their strong antioxidant properties. There is therefore an increasing interest in finding plant foods with low polyamine co…
Cu2+ Coordination Properties of a 2-Pyridine Heptaamine Tripod: Characterization and Binding Mechanism
2009
The synthesis, protonation, and Cu(2+) coordination chemistry of a tripodal heptaamine ligand (L(1)) functionalized with 2-pyridine fragments at the ends of its three branches are reported. L(1) presents six relatively high protonation constants followed by much more reduced constant that as indicated by the UV-vis and NMR data, occur on the pyridine fragments. p[H]-metric, ESI/MS(+), EPR and UV-vis data show that L(1) is able to form mono-, di-, and trinuclear Cu(2+) complexes. Slippage movements and molecular reorganizations have been observed to occur as a function of p[H] in the 1:1 Cu(2+) complexes. The kinetic studies showed that the complex formation is fast and proceeds through a di…
Binding of acrylic and sulphonic polyanions by open-chain polyammonium cations
2000
Abstract The interactions between some acrylic and sulphonic polyanions and some protonated amines (diamines NH 2 -(CH 2 ) x -NH 2 , x =2,…,10; linear tri-, tetra-, penta- and hexa-amines) were studied potentiometrically in aqueous solution, at 25°C. For both types of polyanions AL 2 H i (L − , monomer of polyanion, A, amine) species are formed, with i =1,…, n ( n =number of amino groups in the amine). The stability of these species is strictly dependent on the polyammonium cation charge, and fairly independent of the type of amine (in diamine species maximum stability is observed for x =4, 5). Acrylic and sulphonic polyanion complexes are considerably stronger than analogous species formed…
Polyamines : études et applications
2008
International audience
Methionine Cycle Rewiring by Targeting miR-873-5p Modulates Ammonia Metabolism to Protect the Liver from Acetaminophen
2022
Drug-induced liver injury (DILI) development is commonly associated with acetaminophen (APAP) overdose, where glutathione scavenging leads to mitochondrial dysfunction and hepatocyte death. DILI is a severe disorder without effective late-stage treatment, since N-acetyl cysteine must be administered 8 h after overdose to be efficient. Ammonia homeostasis is altered during liver diseases and, during DILI, it is accompanied by decreased glycine N-methyltransferase (GNMT) expression and S-adenosylmethionine (AdoMet) levels that suggest a reduced methionine cycle. Anti-miR-873-5p treatment prevents cell death in primary hepatocytes and the appearance of necrotic areas in liver from APAP-adminis…