2386-57-4Relevant academic research and scientific papers
Catalytic activity and anion activation in SN2 reactions promoted by complexes of silicon polypodands. Comparison with traditional polyethers
Maia, Angelamaria,Landini, Dario,Betti, Cecilia,Leska, Boguslawa,Schroeder, Grzegorz
, p. 1195 - 1198 (2005)
The catalytic activity of silicon polypodands was evaluated in anion-promoted reactions under solid-liquid phase-transfer catalysis (SL-PTC) conditions and compared with that exhibited by common PTC agents. Results showed that these many-armed ligands are
OH-radical-induced oxidation of methanesulfinic acid. The reactions of the methanesulfonyl radical in the absence and presence of dioxygen
Flyunt, Roman,Makogon, Oksana,Schuchmann, Man Nien,Asmus, Klaus-Dieter,Von Sonntag, Clemens
, p. 787 - 792 (2001)
Hydroxyl radicals were generated radiolytically in N2O-saturated solutions. As shown by pulse radiolysis, methanesulfinic acid reacts with·OH (k = 5.3 × 109 dm3 mol-1 s-1) and N3· giving rise to an intermediate which has an absorption maximum at 330 nm (Gε ≈ 5.2 × 10-5 m2 mol-1). This is attributed to the methanesulfonyl radical, CH3S(O)O·. Pulse radiolysis with conductometric detection indicates that CH3S(O)O· is formed in only ～80% yield. This is confirmed by scavenging experiments with Fe(CN)64-, ascorbate and sulfite, which are oxidised by CH3S(O)O· with rate constants of ～2 × 109 dm3 mol-1 s-1. Steady-state radiolysis of methanesulfinic acid shows that methanesulfonic acid is the major product (G = 2.1 × 10-7 mol J-1). Further products are sulfate (0.7 × 10-7 mol J-1), methane (0.3 × 10-7 mol J-1), ethane (0.08 × 10-7 mol J-1) and dimethyl sulfone (not quantified). It is suggested that an OH-adduct is formed initially which mainly eliminates OH-, but also decomposes yielding ·CH3 and bisulfite. The formation of methanesulfonic acid can be explained by a disproportionation of the methanesulfonyl radicals via recombination and subsequent hydrolysis. In the presence of dioxygen, a chain reaction occurs whereby 2 mol methanesulfonic acid are formed per 1 mol dioxygen consumed. G(methanesulfonic acid) ≈ 250 × 10-7 mol J-1 was found to be independent of dose rate (0.011-0.165 Gy s-1), methanesulfinic acid concentration [(0.1-4) × 10-3 mol dm-3] and dioxygen concentration. An efficient chain process was also observed upon electron beam irradiation [G(methanesulfonic acid) ≈ 200 × 10-7 mol J-1 at 0.8 Gy per pulse and 75 × 10-7 mol J-1 at 9 Gy per pulse (pulse duration 2 μs)]. It is proposed that the oxidation of the substrate by the methylsulfonylperoxyl radical, CH3S(O2)OO·, to give the strongly oxidising CH3S(O2)O· radical, initiates the chain reaction, with the latter propagating the chain by reacting with a substrate molecule to give methanesulfonic acid and the methanesulfonyl radical. Branching and partial removal of the chain-carrying CH3S(O2)O· radicals by H-abstraction from the substrate is suggested as the likely path leading to chain termination. Oxidation of methanesulfinate by ozone (k = 2 × 106 dm3 mol-1 s-1) occurs only by O-atom transfer, and an electron transfer that would start a chain reaction was not observed.
Predicting the hydrolytic breakdown rates of organophosphorus chemical warfare agent simulants using association constants derived from hydrogen bonded complex formation events
Chu, Dominique F.,Clark, Ewan R.,Ellaby, Rebecca J.,Hiscock, Jennifer,Pépés, Antigoni
, (2021/11/22)
Organophosphorus (OP) chemical warfare agents (CWAs) represent an ongoing global threat, through either purposeful environmental release or the need to dispose of historic stockpiles. This presents a need for the development of novel decontamination technologies. Due to the toxic nature and legal limitations placed on OP CWAs, the use of appropriate OP simulants that mimic the reactivity but not the toxicity of the agents themselves is vital to decontamination studies. Herein, we show that association constants derived from non-specific hydrogen bonded complexation events may be used as parameters within models to predict simulant reactivity. We also discuss the limitations that should be placed on such data.
Discovery, Synthesis and Evaluation of a Ketol-Acid Reductoisomerase Inhibitor
Bayaraa, Tenuun,Kurz, Julia L.,Patel, Khushboo M.,Hussein, Waleed M.,Bilyj, Jessica K.,West, Nicholas P.,Schenk, Gerhard,McGeary, Ross P.,Guddat, Luke W.
, p. 8958 - 8968 (2020/07/04)
Ketol-acid reductoisomerase (KARI), the second enzyme in the branched-chain amino acid biosynthesis pathway, is a potential drug target for bacterial infections including Mycobacterium tuberculosis. Here, we have screened the Medicines for Malaria Venture Pathogen Box against purified M. tuberculosis (Mt) KARI and identified two compounds that have Ki values below 200 nm. In Mt cell susceptibility assays one of these compounds exhibited an IC50 value of 0.8 μm. Co-crystallization of this compound, 3-((methylsulfonyl)methyl)-2H-benzo[b][1,4]oxazin-2-one (MMV553002), in complex with Staphylococcus aureus KARI, which has 56 % identity with Mt KARI, NADPH and Mg2+ yielded a structure to 1.72 ? resolution. However, only a hydrolyzed product of the inhibitor (i.e. 3-(methylsulfonyl)-2-oxopropanic acid, missing the 2-aminophenol attachment) is observed in the active site. Surprisingly, Mt cell susceptibility assays showed that the 2-aminophenol product is largely responsible for the anti-TB activity of the parent compound. Thus, 3-(methylsulfonyl)-2-oxopropanic acid was identified as a potent KARI inhibitor that could be further explored as a potential biocidal agent and we have shown 2-aminophenol, as an anti-TB drug lead, especially given it has low toxicity against human cells. The study highlights that careful analysis of broad screening assays is required to correctly interpret cell-based activity data.
Methanesulfonyl Iodide
Rajakaruna, Pradeepa,Gorden, John D.,Stanbury, David M.
supporting information, p. 14752 - 14759 (2019/11/11)
Methanesulfonyl iodide is produced in aqueous solutions from the reaction of triiodide with methanesulfinate. Dichroic crystals of (CH3SO2I)4·KI3·2I2 are formed from KI/I2 solutions with high concentrations of CH3SO2-, while dichroic crystals of (CH3SO2I)2·RbI3 are formed from RbI/I2 solutions. X-ray crystallography of these two compounds shows that the CH3SO2I molecules coordinate through their oxygen atoms to the metal cations and that the S-I bond length is 2.44 ?. At low concentrations of CH3SO2-, the solutions remain homogeneous and the sulfonyl iodide is formed in a rapid equilibrium: CH3SO2- + I3- ? CH3SO2I + 2I-, KMSI = 1.07 ± 0.01 M at 25 °C (μ = 0.1 M, NaClO4). The sulfonyl iodide solutions display an absorbance maximum at 309 nm with a molar absorptivity of 667 M-1 cm-1. Stopped-flow studies reveal that the equilibrium is established within the dead time of the instrument (～2 ms). Solutions of CH3SO2I decompose slowly to form the sulfonate: CH3SO2I + H2O → CH3SO3- + I- + 2H+, khyd. In dilute phosphate buffer, this decomposition occurs with khyd = 2.0 × 10-4 s-1 the decomposition rate shows an inverse-squared dependence on [I-] because of the KMSI equilibrium.
Scaled-up electrochemical reactor with a fixed bed three-dimensional cathode for electro-Fenton process: Application to the treatment of bisphenol A
Chmayssem, Ayman,Taha, Samir,Hauchard, Didier
, p. 435 - 442 (2017/01/09)
In this study, we report on the development of an open undivided electrochemical reactor with a compact fixed bed of glassy carbon pellets as three-dimensional cathode for the application of electro-Fenton process. Bisphenol A (BPA) was chosen as model molecule in order to improve its efficiency to the treatment of persistent pollutants. The study of the BPA removal efficiency in function of the applied current intensity was investigated in order to determine the limiting current of O2 reduction (optimal conditions of H2O2 production at flow rate of 0.36?m3.h?1) which was 0.8?A (0.5?A/100?g of glassy carbon pellets). Many parameters have been carried out using this electro-Fenton reactor namely degradation kinetics, influence of anodic reactions on DSA, effect of initial pollutant concentration. In the optimal current condition, the global production rate of H2O2 and [rad]OH was investigated. The yield of electro-Fenton reaction (conversion of H2O2 to [rad]OH) was very high (>?90%). The absolute rate of BPA degradation was determined as 4.3?×?109?M?1?s?1. COD, TOC and BOD5 measurements indicated that only few minutes of treatment by electro-Fenton process were needed to eliminate BPA for dilute solutions (10 and 25?mg.L?1). In this case, the biodegradability of the treated solutions occurred rapidly. For higher concentration levels, an efficient removal of BPA appeared for treatment time higher than 1?hour and more than 90?minutes were necessary to obtain the biodegradability of BPA solutions. In optimum conditions, the scale-up of the electrochemical reactor applied to electro-Fenton process was suggested and depended on the concentration level of the pollutant. The operating parameters of the scaled-up reactor might be deduced from the new section of each fixed bed exposed to the flow, from values of liquid flow velocity and from the corresponding limiting current density obtained with the reactor at laboratory scale. The compact fixed bed cathode in an open undivided electrochemical reactor appears as an appropriate solution as pre-treatment electro-Fenton process followed by the biological treatment of persistent pollutant.
The reduced flavin-dependent monooxygenase SfnG converts dimethylsulfone to methanesulfinate
Wicht, Denyce K.
, p. 159 - 166 (2016/07/22)
The biochemical pathway through which sulfur may be assimilated from dimethylsulfide (DMS) is proposed to proceed via oxidation of DMS to dimethylsulfoxide (DMSO) and subsequent conversion of DMSO to dimethylsulfone (DMSO2). Analogous chemical oxidation processes involving biogenic DMS in the atmosphere result in the deposition of DMSO2 into the terrestrial environment. Elucidating the enzymatic pathways that involve DMSO2 contribute to our understanding of the global sulfur cycle. Dimethylsulfone monooxygenase SfnG and flavin mononucleotide (FMN) reductase MsuE from the genome of the aerobic soil bacterium Pseudomonas fluorescens Pf0-1 were produced in Escherichia coli, purified, and biochemically characterized. The enzyme MsuE functions as a reduced nicotinamide adenine dinucleotide (NADH)-dependent FMN reductase with apparent steady state kinetic parameters of Km = 69 μM and kcat/Km = 9 min?1 μM ?1 using NADH as the variable substrate, and Km = 8 μM and kcat/Km = 105 min?1 μM ?1 using FMN as the variable substrate. The enzyme SfnG functions as a flavoprotein monooxygenase and converts DMSO2 to methanesulfinate in the presence of FMN, NADH, and MsuE, as evidenced by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The results suggest that methanesulfinate is a biochemical intermediate in sulfur assimilation.
Chloride triggered reversible switching from a metallosupramolecular [Pd2L4]4+ cage to a [Pd2L2Cl4] metallo-macrocycle with release of endo- and exo-hedrally bound guests
Preston, Dan,Fox-Charles, Alyssa,Lo, Warrick K. C.,Crowley, James D.
supporting information, p. 9042 - 9045 (2015/05/27)
A metallosupramolecular [Pd2L4]4+ cage can be cleanly converted into a [Pd2L2Cl4] metallo-macrocycle upon addition of chloride ions. The process is reversible, treatment of the [Pd2L2Cl4] macrocycle with silver(i) ions regenerates the [Pd2L4]4+ cage. Additionally, it is shown that guest molecules could be released on chloride triggered cage dis-assembly and taken up anew on re-assembly. This journal is
POLYMYXIN DERIVATIVES AND USES THEREOF
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Page/Page column, (2014/06/24)
The present invention relates to a polymyxin derivative and to a combination product comprising at least two such derivatives. The invention further relates to a method for treating, alleviating or ameliorating an infection in a subject caused by a Gram-negative bacterium, by administering a therapeutically effective amount of a derivative according to the present invention to said subject; to a method for sensitizing Gram-negative bacteria to an antibacterial agent by administering, simultaneously or sequentially in any order a therapeutically effective amount of said antibacterial agent and a derivative according to the present invention to said subject; to methods for developing novel antibiotics; for reducing the nephrotoxicity, for improving the pharmacokinetic properties of natural polymyxins and octapeptins; and for sensitizing clinically important bacteria to a host defense mechanism complement present in serum. Finally, the invention relates to a process for preparing such polymyxin derivatives.
Photochemical cleavage reactions of 8-quinolinyl sulfonates in aqueous solution
Kageyama, Yoshiyuki,Ohshima, Ryosuke,Sakurama, Kazusa,Fujiwara, Yoshihisa,Tanimoto, Yoshifumi,Yamada, Yasuyuki,Aoki, Shin
experimental part, p. 1257 - 1266 (2010/05/02)
Photochemical cleavage reactions of 8-quinolinyl benzenesulfonate derivatives and related sulfonates in aqueous solutions are reported. The 8-quinolinyl benzenesulfonates undergo photolysis upon photoirradiation at 300-330 nm to give the corresponding 8-quinolinols and benzenesulfonic acids with the production of only negligible amounts of byproducts. The effects of substituent groups of the 8-quinolinyl moiety and the benzene ring on the photolysis reactions were examined. Based on steady-state mechanistic studies using a triplet sensitizer, a triplet quencher, and electron donors, it was suggested that the photolysis proceeds mainly via the homolytic cleavage of S-O bonds in the excited triplet state.
