1,721,023 research outputs found
A facile one-pot synthesis of 8-oxo-7,8-dihydro-(2′-deoxy)adenosine in water
Full text linkReaction of 2-mercaptoethanol with 8-bromo-2′-deoxyadenosine and 8-bromo-adenosine in aqueous solution and in the presence of triethylamine gave the 8-oxo-adenine derivatives in very good yields. Some mechanistic details are reported.Fil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; ItaliaFil: Navacchia, Maria Luisa. Consiglio Nazionale delle Ricerche; ItaliaFil: Postigo, Jose Alberto. Universidad de Belgrano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
A convenient route to mono-trans polyunsaturated free fatty acids
Full text linkTrans unsaturated fatty acids in humans may be originated both from dietary supplementation and from an endogenous free-radical-catalyzed cis−trans isomerization of fatty acid residues in naturally occurring cis lipids. The latter process affords geometrical isomers and the polyunsaturated fatty acid mono-trans isomers were demonstrated to be connected with stress conditions in living organisms. Synthesis of mono-trans polyunsaturated fatty acid is useful for analytical and biological research, and in this case, the availability of free fatty acids is needed as well as the possibility of mg scale of the synthetic protocol. Herein, we report a simple synthetic route to mono-trans isomers of arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which includes thiyl radical-catalyzed isomerization reaction of polyunsaturated fatty acid methyl esters and fraction isolation of mono-trans mixture isomers followed by optimization of hydrolysis condition to free fatty acids and purification of each mono-trans polyunsaturated fatty acid. Our approach to mono-trans polyunsaturated fatty acids as free acids can reach the mg scale, thus fostering more applications to biochemical and biological studies
The radical-based reduction with (TMS)3SiH 'on water'
Full text linkReduction of different organohalides, bromonucleosides among them, was successfully carried out in yields ranging from 75% to quantitative, using (TMS)3SiH in a heterogeneous system with water as the solvent. Our procedure, employing 2-mercaptoethanol as the catalyst and the hydrophobic diazo-compound ACCN as the initiator, illustrates that (TMS)3SiH can be the radical-based reducing agent of choice in aqueous medium. (TMS) 3SiH does not suffer from any significant reaction with water and can safely be used with additional benefit, such as ease of purification and environmental compatibility.Fil: Postigo, Jose Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; ItaliaFil: Navacchia, Maria Luisa. Consiglio Nazionale delle Ricerche; ItaliaFil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; Itali
Hydrogen Sulfide: A Reagent for pH-Driven Bioinspired 1,2-Diol Mono-deoxygenation and Carbonyl Reduction in Water
Full text linkHydrogen sulfide (H2S) was evaluated for its peculiar sulfur radical species generated at different pHs and was used under photolytical conditions in aqueous medium for the reduction of 1,2-diols to alcohols. The conversion steps of 1,2-cyclopentanediol to cyclopentanol via cyclopentanone were analyzed, and it was proven that the reaction proceeds via a dual catalytic/radical chain mechanism. This approach was successfully adapted to the reduction of a variety of carbonyl compounds using H2S at pH 9 in water. This work opens up the field of environmental friendly synthetic processes using the pH-driven modulation of reactivity of this simple reagent in water.Fil: Barata Vallejo, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consiglio Nazionale delle Ricerche; ItaliaFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; ItaliaFil: Golding, Bernard T.. University of Newcastle; Reino UnidoFil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; Itali
Hydroxyl Radical vs. One-Electron Oxidation Reactivities in an Alternating GC Double-Stranded Oligonucleotide: A New Type Electron Hole Stabilization
No full text: We examined the reaction of hydroxyl radicals (HO•) and sulfate radical anions (SO4•-), which is generated by ionizing radiation in aqueous solutions under anoxic conditions, with an alternating GC doubled-stranded oligodeoxynucleotide (ds-ODN), i.e., the palindromic 5'-d(GCGCGC)-3'. In particular, the optical spectra of the intermediate species and associated kinetic data in the range of ns to ms were obtained via pulse radiolysis. Computational studies by means of density functional theory (DFT) for structural and time-dependent DFT for spectroscopic features were performed on 5'-d(GCGC)-3'. Comprehensively, our results suggest the addition of HO• to the G:C pair moiety, affording the [8-HO-G:C]• detectable adduct. The previous reported spectra of one-electron oxidation of a variety of ds-ODN were assigned to [G(-H+):C]• after deprotonation. Regarding 5'-d(GCGCGC)-3' ds-ODN, the spectrum at 800 ns has a completely different spectral shape and kinetic behavior. By means of calculations, we assigned the species to [G:C/C:G]•+, in which the electron hole is predicted to be delocalized on the two stacked base pairs. This transient species was further hydrated to afford the [8-HO-G:C]• detectable adduct. These remarkable findings suggest that the double-stranded alternating GC sequences allow for a new type of electron hole stabilization via delocalization over the whole sequence or part of it
trans-Double Bond-Containing Liposomes as Potential Carriers for Drug Delivery
Full text linkThe use of liposomes has been crucial for investigations in biomimetic chemical biology as a membrane model and in medicinal chemistry for drug delivery. Liposomes are made of phospholipids whose biophysical characteristics strongly depend on the type of fatty acid moiety, where natural unsaturated lipids always have the double bond geometry in the cis configuration. The influence of lipid double bond configuration had not been considered so far with respect to the competence of liposomes in delivery. We were interested in evaluating possible changes in the molecular properties induced by the conversion of the double bond from cis to trans geometry. Here we report on the effects of the addition of trans-phospholipids supplied in different amounts to other liposome constituents (cholesterol, neutral phospholipids and cationic surfactants), on the size, ζ-potential and stability of liposomal formulations and on their ability to encapsulate two dyes such as rhodamine B and fluorescein. From a biotechnological point of view, trans-containing liposomes proved to have different characteristics from those containing the cis analogues, and to influence the incorporation and release of the dyes. These results open new perspectives in the use of the unnatural lipid geometry, for the purpose of changing liposome behavior and/or of obtaining molecular interferences, also in view of synergic effects of cell toxicity, especially in antitumoral strategies
Revisiting the reaction of hydroxyl radicals with vicinal diols in water
Full text linkThe carbonyl products of the reactions of hydroxyl radicals with three vicinal diols (ethane-1,2-diol, propane-1,2-diol and butane-2,3-diol) have been identified and quantified. Hydroxyl radicals were produced by gamma-radiolysis of N2O-saturated aqueous solutions. The reactions result in the formation of alkoxyl radicals (15%) followed by beta-fragmentation, and alpha-hydroxyl alkyl radicals that undergo H2O elimination. The latter process is part of a radical chain reaction at higher diol concentrations.Fil: Jiang, Dong. University of Newcastle; Reino UnidoFil: Barata Vallejo, Sebastian. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica. Cátedra de Química Orgánica I; ArgentinaFil: Golding, Bernard T.. University of Newcastle; Reino UnidoFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; ItaliaFil: Chatgilialoglu, Chryssostomos. Consiglio Nazionale delle Ricerche; Itali
Bleomycin-induced trans lipid formation in cell membranes and in liposome models
Full text linkCell cultures of NTera-2 cells incubated with bleomycin and liposomes as biomimetic models of cell membranes were used for examining some novel aspects of drug-metal induced reactivity with unsaturated lipids under oxidative conditions. In cell cultures, bleomycin was found for the first time to cause the formation of trans fatty acids. The chemical basis of this transformation was ascertained by liposome experiments, using bleomycin-iron complexes in the presence of thiol as a reducing agent that by incubation at 37 °C gave rise to the thiyl radical-catalysed double bond isomerisation of membrane phospholipids. The effect of oxygen and reagent concentrations on the reaction outcome was studied. An interesting scenario of free radical reactivity is proposed, which can be relevant for understanding the role of membrane lipids in antitumoral treatments and drug carrier interaction.Fil: Cort, Aysegul. Akdeniz University. Faculty of Medicine; Turquía. Consiglio Nazionale delle Ricerche; ItaliaFil: Ozben, Tomris. Akdeniz University. Faculty of Medicine; TurquíaFil: Sansone, Anna. Consiglio Nazionale delle Ricerche; ItaliaFil: Barata Vallejo, Sebastian. Consiglio Nazionale delle Ricerche; Italia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chatgilialoglu, Chryssostomos. Demokritos National Centre For Scientific Research; GreciaFil: Ferreri, Carla. Consiglio Nazionale delle Ricerche; Itali
Biomimetic Radical Chemistry and Applications 2021
Full text linkThe high importance of free radical chemistry for a variety of biological events, including ageing and inflammation, has attracted considerable interest in understanding the related mechanistic steps at the molecular level. Modelling the free radical chemical reactivity of biological systems is an important research area. When studying free-radical-based chemical mechanisms, biomimetic chemistry and the design of established biomimetic models come into play to perform experiments in a controlled environment, suitably designed to be a similar as possible to cellular conditions. This Special Issue provides readers with a wide overview of biomimetic radical chemistry, where molecular mechanisms have been defined and molecular libraries of products are developed to be used as traces for the discoveries of some relevant biological processes. Several subjects are presented, with five articles and five reviews written by specialists in the fields of DNA, proteins, lipids, biotechnological applications and bioinspired synthesis, with “free radicals” as the common denominator
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