75-50-3Relevant articles and documents
γ-irradiated [(CH3)4N]2SiF6 single crystal investigation by electron paramagnetic resonance technique
Bozkurt,Kartal, I.,Karabulut
, p. 308 - 310 (2007)
In this study, γ-irradiation damage centers in [(CH3)4N]2SiF6 single crystal has been investigated by electron paramagnetic resonance spectroscopy (EPR) at room temperature. It has been found that γ-irradiation produces the (CH3)3 over(N, ?)+ radicals in this compound. The g factor and the hyperfine constant for H atoms, measured as 28.7 G, were found to be isotropic. The hyperfine coupling constant of the N nucleus, observed (CH3)3 over(N, ?)+ hole radical in [(CH3)4N]2SiF6 was found to be anisotropic with A// = 15 and A⊥ = 23 G, respectively. This means that each methyl groups rotate around the C3 ν-axis and they also rotate around the C3 ν-axis of (CH3)3 over(N, ?)+ radical. These results were compared with the earlier studies in (CH3)3 over(N, ?)+ radical and discussed.
Novel self assembling nanoparticles for the oral administration of fondaparinux: Synthesis, characterization and in vivo evaluation
Ralay-Ranaivo, Bettina,Desma?le, Didier,Bianchini, Elsa P.,Lepeltier, Elise,Bourgaux, Claudie,Borgel, Delphine,Pouget, Thierry,Tranchant, Jean Fran?ois,Couvreur, Patrick,Gref, Ruxandra
, p. 323 - 331 (2014)
Fondaparinux (Fpx) is the anticoagulant of choice in the treatment of short- and medium-term thromboembolic disease. To overcome the low oral bioavailability of Fpx, a new nanoparticulate carrier has been developed. The nanoparticles (NPs) contain squalenyl derivatives, known for their excellent oral bioavailability. They spontaneously self-assemble upon both electrostatic and hydrophobic interactions between the polyanionic Fpx and cationic squalenyl (CSq) derivatives. The preparation conditions were optimized to obtain monodisperse, stable NPs with a mean diameter in the range of 150-200 nm. The encapsulation efficiencies were around 80%. Fpx loadings reached 39 wt.%. According to structural and morphological analysis, Fpx and CSq organized in spherical multilamellar ("onion-type") nanoparticles. Furthermore, in vivo studies in rats suggested that Fpx was well absorbed from the orally administered NPs, which totally dissociated when reaching the blood stream, leading to the release of free Fpx. The Fpx:CSq NPs improved the plasmatic concentration of Fpx in a dose-dependent manner. However, the oral bioavailability of these new NPs remained low (around 0.3%) but of note, the Cmax obtained after oral administration of 50 mg/kg NPs was close to the prophylactic plasma concentration needed to treat venous thromboembolism. Moreover, the oral bioavailability of Fpx could be dramatically increased up to 9% by including the nanoparticles into gastroresistant capsules. This study opens up new perspectives for the oral administration of Fpx and paves the way towards elaborating squalene-based NPs which self assemble without the need of covalently grafting the drug to Sq.
Replica of a fishy enzyme: Structure-function analogue of trimethylamine-n-oxide reductase
Moula, Golam,Bose, Moumita,Sarkar, Sabyasachi
, p. 5316 - 5327 (2013)
Three new complexes, [MoIVO(mnt)(SS)]2- (SS = dimethylethylenedicarboxylate (DMED), toluenedithiolate (tdt), benzenedithiolate (bdt); mnt = maleonitriledithiolate), each possessing two different dithiolene ligands, are synthesized as model of trimethylamine-N-oxide reductase. The asymmetric dithiolene ligands present in these complexes simulate the two different (P and Q) pterin coordinations in the family of DMSO reductase. These complexes reduce trimethylamine-N-oxide ((CH3)3N +-O- or TMANO), the biological substrate of trimethylamine-N-oxide reductase, to trimethylamine ((CH3) 3N), responsible for the fishy smell of dead aquatic animals. The reaction kinetics of trimethylamine-N-oxide reduction by these complexes follow the Michaelis-Menten saturation kinetics. These experimental findings have been rationalized by DFT, TD-DFT level of calculations.
Electrochemical decomposition of choline chloride based ionic liquid analogues
Haerens, Kurt,Matthijs, Edward,Binnemans, Koen,Van Der Bruggen, Bart
, p. 1357 - 1365 (2009)
Ionic liquids are studied intensively for electrochemical applications and more specifically for the electrodeposition of metals. In this paper the electrochemical stability of a deep-eutectic solvent based on choline chloride and ethylene glycol is studied over longer periods of electrolysis. The formation of several decomposition products such as 2-methyl-1,3-dioxolane was observed. Possible mechanisms for the formation of these products are given: some products involve a reaction at either the anode or the cathode, while others can be explained by consecutive reactions of reaction products formed at both electrodes. A range of chlorinated products like chloromethane, dichloromethane and chloroform could be detected as well. This is remarkable as evolution of chlorine gas at the anode is not observed. The formation of the chlorinated products is ascribed to the existence of the Cl3 - ion in the solution. The presence of the Cl3- ion was observed photometrically. The presence of chlorinated products gives rise to a larger environmental impact and higher risks for health and safety, and it questions the "greenness" of these ionic liquid analogues. To reduce the decomposition of the solvent, water and easily oxidizable acids were added as 'sacrificial agents'. Their influence on the formation of 2-methyl-1,3-dioxolane was quantified. However, the addition of the sacrificial agents did not improve the stability of the solvent. Addition of formic acid reduced the formation of 2-methyl-1,3-dioxolane but chlorinated products could still be detected. Water reduced the formation of chlorinated products. The Royal Society of Chemistry 2009.
Structural basis of carnitine monooxygenase CntA substrate specificity, inhibition, and intersubunit electron transfer
Bugg, Timothy D. H.,Cameron, Alexander D.,Chen, Yin,Jameson, Eleanor,Quareshy, Mussa,Shanmugam, Muralidharan,Townsend, Eleanor
, (2021)
Microbial metabolism of carnitine to trimethylamine (TMA) in the gut can accelerate atherosclerosis and heart disease, and these TMA-producing enzymes are therefore important drug targets. Here, we report the first structures of the carnitine oxygenase CntA, an enzyme of the Rieske oxygenase family. CntA exists in a head-to-tail α3 trimeric structure. The two functional domains (the Rieske and the catalytic mononuclear iron domains) are located >40 A apart in the same monomer but adjacent in two neighboring monomers. Structural determination of CntA and subsequent electron paramagnetic resonance measurements uncover the molecular basis of the so-called bridging glutamate (E205) residue in intersubunit electron transfer. The structures of the substrate-bound CntA help to define the substrate pocket. Importantly, a tyrosine residue (Y203) is essential for ligand recognition through a π- cation interaction with the quaternary ammonium group. This interaction between an aromatic residue and quaternary amine substrates allows us to delineate a subgroup of Rieske oxygenases (group V) from the prototype ring-hydroxylating Rieske oxygenases involved in bioremediation of aromatic pollutants in the environment. Furthermore, we report the discovery of the first known CntA inhibitors and solve the structure of CntA in complex with the inhibitor, demonstrating the pivotal role of Y203 through a π-π stacking interaction with the inhibitor. Our study provides the structural and molecular basis for future discovery of drugs targeting this TMA-producing enzyme in human gut.
Heterogeneous platinum catalysts for direct synthesis of trimethylamine by N-methylation of ammonia and its surrogates with CO2/H2
Toyao, Takashi,Siddiki, S. M. A. Hakim,Ishihara, Keisuke,Kon, Kenichi,Onodera, Wataru,Shimizu, Ken-Ichi
, p. 68 - 70 (2017)
Direct synthesis of trimethylamine through N-methylation of NH3 or its surrogate (NH4HCO3) with both CO2 and H2 has been achieved by employing Pt and MoOx coloaded TiO2 (Pt-MoOx/TiO2). Pt-MoOx/TiO2 was found to be superior to other supported Pt and transition-metal-loaded MoOx/TiO2 catalysts for the trimethylamine synthesis process.
Deoxygenation of primary amides to amines with pinacolborane catalyzed by Ca[N(SiMe3)2]2(THF)2
Gong, Mingliang,Guo, Chenjun,Jiang, Linhong,Luo, Yunjie,Yu, Chong
supporting information, p. 1201 - 1206 (2021/05/29)
Deoxygenative reduction of amides is a challenging but favorable synthetic method of accessing amines. In the presence of a catalytic amount of Ca[N(SiMe3)2]2(THF)2, pinacolborane (HBpin) could efficiently reduce a broad scope of amides, primary amides in particular, into corresponding amines. Functional groups and heteroatoms showed good tolerance in this process of transformation, and a plausible reaction mechanism was proposed.
Lithium compound catalyzed deoxygenative hydroboration of primary, secondary and tertiary amides
Bisai, Milan Kumar,Gour, Kritika,Das, Tamal,Vanka, Kumar,Sen, Sakya S.
supporting information, p. 2354 - 2358 (2021/03/03)
A selective and efficient route for the deoxygenative reduction of primary to tertiary amides to corresponding amines has been achieved with pinacolborane (HBpin) using simple and readily accessible 2,6-di-tert-butyl phenolate lithium·THF (1a) as a catalyst. Both experimental and DFT studies provide mechanistic insight. This journal is
Reduction of Amides to Amines with Pinacolborane Catalyzed by Heterogeneous Lanthanum Catalyst La(CH2C6H4NMe2- o)3@SBA-15
Guo, Chenjun,Zhang, Fangcao,Yu, Chong,Luo, Yunjie
supporting information, p. 13122 - 13135 (2021/08/31)
Hydroboration of amides is a useful synthetic strategy to access the corresponding amines. In this contribution, it was found that the supported lanthanum benzyl material La(CH2C6H4NMe2-o)3@SBA-15 was highly active for the hydroboration of primary, secondary, and tertiary amides to amines with pinacolborane. These reactions selectively produced target amines and showed good tolerance for functional groups such as -NO2, -halogen, and -CN, as well as heteroatoms such as S and O. This reduction procedure exhibited the recyclable and reusable property of heterogeneous catalysts and was applicable to gram-scale synthesis. The reaction mechanisms were proposed based on some control experiments and the previous literature. This is the first example of hydroborative reduction of amides to amines mediated by heterogeneous catalysts.
In Vitro Reconstitution of a Five-Step Pathway for Bacterial Ergothioneine Catabolism
Beliaeva, Mariia A.,Leisinger, Florian,Seebeck, Florian P.
, p. 397 - 403 (2021/03/08)
Ergothioneine is a histidine-derived sulfur metabolite that is biosynthesized by bacteria and fungi. Plants and animals absorb ergothioneine as a micronutrient from their environment or nutrition. Several different mechanisms of microbial ergothioneine production have been described in the past ten years. Much less is known about the genetic and structural basis for ergothioneine catabolism. In this report, we describe the in vitro reconstitution of a five-step pathway that degrades ergothioneine to l-glutamate, trimethylamine, hydrogen sulfide, carbon dioxide, and ammonia. The first two steps are catalyzed by the two enzymes ergothionase and thiourocanate hydratase. These enzymes are closely related to the first two enzymes in histidine catabolism. However, the crystal structure of thiourocanate hydratase from the firmicute Paenibacillus sp. reveals specific structural features that strictly differentiate the activity of this enzyme from that of urocanate hydratases. The final two steps are catalyzed by metal-dependent hydrolases that share most homology with the last two enzymes in uracil catabolism. The early and late part of this pathway are connected by an entirely new enzyme type that catalyzes desulfurization of a thiohydantoin intermediate. Homologous enzymes are encoded in many soil-dwelling firmicutes and proteobacteria, suggesting that bacterial activity may have a significant impact on the environmental availability of ergothioneine.
