10 research outputs found

    Lipase-Catalyzed Acetylation and Esterification of Bile Acids

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    In this chapter we describe the application of lipases as catalysts in reactions on a relevant family of steroids: the bile acids. Twenty three mono-, diacetyl and ester derivatives of deoxycholic-, chenodeoxycholic-, lithocholic- and cholic acid, fifteen of them new compounds, were obtained through lipase-catalyzed acetylation, esterification and alcoholysis reactions in very good to excellent yield and a highly regioselective way. Among them, acetylated ester products, in which the lipase catalyzed both reactions in one-pot, were obtained. The influence of various reaction parameters in the enzymatic reactions, such as enzyme source, nucleophile/substrate ratio, enzyme/substrate ratio, solvent and temperature, was studied. Some of the reported products are novel and it is not possible to obtain them satisfactorily by following traditional synthetic procedures. Due to its singular structure containing three hydroxyl groups, cholic acid showed a different behavior in the enzymatic reactions, from that observed for the other three bile acids studied. In order to shed light to different behavior of bile acids in the enzymatic reactions, molecular modeling was applied to substrates and some derivatives.Fil: Baldessari, Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanålisis y Métodos Físicos en Química Orgånica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanålisis y Métodos Físicos en Química Orgånica; ArgentinaFil: Garcia Liñares, Guadalupe Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanålisis y Métodos Físicos en Química Orgånica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanålisis y Métodos Físicos en Química Orgånica; Argentin

    Chemoenzymatic Synthesis of Nitrogen Polymers with Biomedical Applications Catalyzed by Lipases

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    The application of Candida antarctica lipase B as catalyst in the synthesis of two examples of nitrogen polymers is described. Firstly, we report anovel linear polyamidoamine oligomer, obtained by polymerization of ethyl acrylate and N-methyl-1,3-diaminopropane, catalyzed by Candida antarctica lipase B immobilized on polypropylene. The second part of the chapter describes an efficient route for the synthesis of a novel ÎČ-peptoid oligomer with hydroxyalkyl pendant groups in the nitrogen atom, through the polymerization of ethyl N-(2-hydroxyethyl)-ÎČ-alaninate catalyzed by Candida antarctica lipase B physically adsorbed within a macroporous poly(methyl methacrylate-co-butyl methacrylate) resin.Moreover,two derivatives of the ÎČ-peptoid oligomer were prepared: by acetylation and by grafting polycaprolactone. This last process was performed through ring opening polymerization of caprolactone from the ÎČ-peptoid pendant hydroxyl groups and afforded a brush copolymer. The products were blended with polycaprolactone to make films by solvent casting. The inclusion of the acyl derivatives of the ÎČ-peptoid to polycaprolactone affected the morphology of the film yielding micro- and nanostructured patterns.The obtained products showed biomedical applications.Fil: Baldessari, Alicia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Unidad de MicroanĂĄlisis y MĂ©todos FĂ­sicos en QuĂ­mica OrgĂĄnica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de MicroanĂĄlisis y MĂ©todos FĂ­sicos en QuĂ­mica OrgĂĄnica; ArgentinaFil: Garcia Liñares, Guadalupe Eugenia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Unidad de MicroanĂĄlisis y MĂ©todos FĂ­sicos en QuĂ­mica OrgĂĄnica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de MicroanĂĄlisis y MĂ©todos FĂ­sicos en QuĂ­mica OrgĂĄnica; Argentin

    Functional crosstalk of PGC-1 coactivators and inflammation in skeletal muscle pathophysiology

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    Skeletal muscle is an organ involved in whole body movement and energy metabolism with the ability to dynamically adapt to different states of (dis-)use. At a molecular level, the peroxisome proliferator-activated receptor Îł coactivators 1 (PGC-1s) are important mediators of oxidative metabolism in skeletal muscle and in other organs. Musculoskeletal disorders as well as obesity and its sequelae are associated with PGC-1 dysregulation in muscle with a concomitant local or systemic inflammatory reaction. In this review, we outline the function of PGC-1 coactivators in physiological and pathological conditions as well as the complex interplay of metabolic dysregulation and inflammation in obesity with special focus on skeletal muscle. We further put forward the hypothesis that, in this tissue, oxidative metabolism and inflammatory processes mutually antagonize each other. The nuclear factor ÎșB (NF-ÎșB) pathway thereby plays a key role in linking metabolic and inflammatory programs in muscle cells. We conclude this review with a perspective about the consequences of such a negative crosstalk on the immune system and the possibilities this opens for clinical applications

    Measurements of neutrino oscillation parameters from the T2K experiment using 3.6 x 1021 protons on target

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    Measurements of neutrino oscillation parameters from the T2K experiment using 3.6×10213.6\times10^{21} protons on target

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    International audienceThe T2K experiment presents new measurements of neutrino oscillation parameters using 19.7(16.3)×102019.7(16.3)\times10^{20} protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7×10204.7\times10^{20} POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin⁥2Ξ13\sin^2\theta_{13} and the impact of priors on the ÎŽCP\delta_\mathrm{CP} measurement. Both analyses prefer the normal mass ordering and upper octant of sin⁥2Ξ23\sin^2\theta_{23} with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin⁥2Ξ13\sin^2\theta_{13} from reactors, sin⁥2Ξ23=0.561−0.032+0.021\sin^2\theta_{23}=0.561^{+0.021}_{-0.032} using Feldman--Cousins corrected intervals, and Δm322=2.494−0.058+0.041×10−3 eV2\Delta{}m^2_{32}=2.494_{-0.058}^{+0.041}\times10^{-3}~\mathrm{eV^2} using constant Δχ2\Delta\chi^{2} intervals. The CP-violating phase is constrained to ÎŽCP=−1.97−0.70+0.97\delta_\mathrm{CP}=-1.97_{-0.70}^{+0.97} using Feldman--Cousins corrected intervals, and ÎŽCP=0,π\delta_\mathrm{CP}=0,\pi is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2σ2\sigma credible level using a flat prior in ÎŽCP\delta_\mathrm{CP}, and just below 2σ2\sigma using a flat prior in sin⁥ΎCP\sin\delta_\mathrm{CP}. When the external constraint on sin⁥2Ξ13\sin^2\theta_{13} is removed, sin⁥2Ξ13=28.0−6.5+2.8×10−3\sin^2\theta_{13}=28.0^{+2.8}_{-6.5}\times10^{-3}, in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses

    First measurement of muon neutrino charged-current interactions on hydrocarbon without pions in the final state using multiple detectors with correlated energy spectra at T2K

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    This paper reports the first measurement of muon neutrino charged-current interactions without pions in the final state using multiple detectors with correlated energy spectra at T2K. The data was collected on hydrocarbon targets using the off-axis T2K near detector (ND280) and the on-axis T2K near detector (INGRID) with neutrino energy spectra peaked at 0.6 GeV and 1.1 GeV, respectively. The correlated neutrino flux presents an opportunity to reduce the impact of the flux uncertainty and to study the energy dependence of neutrino interactions. The extracted double-differential cross sections are compared to several Monte Carlo neutrino-nucleus interaction event generators showing the agreement between both detectors individually and with the correlated result
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