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  • 1.
    Agnemo, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten.
    Ligniners reaktioner med alkalisk väteperoxid1981Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Under alkaline conditions hydrogen peroxide can be used either as a 1ignin-degrading or a 1ignin-preserving bleaching agent. If heavy metal ions are present and/or silicate is absent in the reaction medium, hydrogen peroxide decomposes via hydroxyl radicals and superoxide ions to oxygen and water. These decomposition products are able to react for example with phenolic lignin structures and thereby cause a partial degradation of lignin. In such a system peroxide could act as a bleaching and delignifying agent at the same time and these properties can be utilized for the bleaching of chemical pulps.In order to elucidate the factors which influence the degradation of phenolic structures by oxidation with alkaline hydrogen peroxide the lignin model compounds-methylsyringyl alcohol was studied.By determining the first order reaction rate constants for the oxidation, the main results which were obtained indicate that phenolic lignin structures can be efficiently degraded especially if:A. The pH in the bleaching liquor is close to the pK -valueàfor hydrogen peroxide.B. The ionic strength in the bleaching medium is as high as possible.C. A fixed amount of heavy metal ions (manganese) is added to the bleaching liquor.In the presence of silicate and diethylentriaminepenta-acetic acid (DTPA) hydrogen peroxide is stabilized against decomposition. Under these conditions alkaline hydrogen peroxide is able to react only with lignin units containing conjugated carbonyl groups such as quinone, aryl-oe-carbonyl and cinnamaldehyd structures, leading to an elimination of the chromophoric structures without any substantial dissolution of lignin. In this part of work we have elucidated the kinetic behavior and the reaction products from lignin model compounds of the aryl-of- carbonyl and cinnamaldehyde types.1,2-Diarylpropan-1,3,-diol structures constitute an important building unit in native lignins. We have demonstrated that under hydrogen peroxide bleaching conditions the model compound 2,3--bis(4-hydroxy-3-methoxyphenyl)-3-ethoxy-propanol was converted to stilbenes, ûe. structures which when present in pulps may contribute to a rapid yellowing. The results obtained with model compounds under simulated lignin retaining bleaching conditions demonstrate that there are possibilities to improve the bleaching of mechanical pulps with hydrogen peroxide if:A. The remaining heavy metal ions complexed with DTPA are present in their lowest valence states.B. The concentration of hydroperoxy ions can be maintained at a high level at the lowest possible pH-value.

  • 2. Aguilera, Adriana Freites
    et al.
    Tolvanen, Pasi
    Heredia, Shuyana
    Muñoz, Marta González
    Samson, Tina
    Oger, Adrien
    Verove, Antoine
    Eränen, Kari
    Leveneur, Sebastien
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Salmi, Tapio
    Epoxidation of fatty acids and vegetable oils assisted by microwaves catalyzed by a cation exchange resin2018Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, nr 11, s. 3876-3886Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Epoxidation of oleic acid and cottonseed oil was conducted in a semibatch reactor with in-situ-formed percarboxylic acid (peracetic acid or perpropionic acid), using hydrogen peroxide as an oxidizing agent and carboxylic acid (acetic acid or propionic acid) as oxygen carriers. Amberlite IR-120 was implemented as the catalyst. The system was comprised of a loop reactor, where the mixture was pumped through a single-mode cavity in which microwave irradiation was introduced. A heat exchanger was integrated into the system to replace microwave heating, to compare the results obtained via microwave heating versus conventional heating. The catalyst loading effect was studied, as well as the influence of microwave irradiation and the implementation of the SpinChem rotating bed reactor (RBR), in hopes of decreasing the influence of the internal mass transfer. The application of microwave irradiation results in an improvement of the reaction yield in the absence of a catalyst.

  • 3. Aguilera, Adriana Freites
    et al.
    Tolvanen, Pasi
    Oger, Adrien
    Eränen, Kari
    Leveneur, Sébastien
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku-Åbo, Finland.
    Salmi, Tapio
    Screening of ion exchange resin catalysts for epoxidation of oleic acid under the influence of conventional and microwave heating2019Inngår i: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: For many chemical systems, it is of great importance to find a durable, active and efficient catalyst that improves the process performance. Epoxidation of oleic acid with peracetic acid (Prilezhaev oxidation) was carried out in an isothermal loop reactor in the presence of heterogeneous catalysts. The kinetic experiments conducted under microwave heating (MW) were compared with identical experiments carried out under conventional (conductive/convective) heating. Extensive screening of heterogeneous catalysts was conducted and the influence of microwave irradiation on the reaction kinetics was studied. Several ion exchange resins were screened to explore their applicability and activity in the epoxidation of oleic acid. The perhydrolysis reaction (peracetic acid formed in situ from acetic acid and H2O2) was promoted with the use of various solid acid catalysts: Amberlite IR-120, Amberlyst 15, Smopex®, Dowex 50x8-100, Dowex 50x8-50, Dowex 50x2-100 and Nafion™.

    Results: From the selected group of catalysts, Dowex 50-x8100 and Dowex 50x8-50 produced the highest yield of epoxidized oil. Only minor differences in the reactant conversion and the product yield were found in the experiments carried out under microwave exposure compared to the conventionally heated experiments in the presence of several ion exchange resins.

    Conclusions: The catalytic effect was much more prominent than the microwave effect, because the solid acid catalysts enhanced the slow step of the process, the perhydrolysis of acetic acid. The catalytic effect was very dominant and a considerable improvement of the oleic acid conversion and the epoxide yield was observed in the presence of the top-performing catalysts.

  • 4.
    Albers, Michael F
    et al.
    Department of Chemical Biology, Max Planck Institute for Molecular Physiology.
    Hedberg, Christian
    Amino acid building blocks for Fmoc solid-phase synthesis of peptides phosphocholinated at serine, threonine, and tyrosine2013Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, nr 6, s. 2715-2719Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phosphocholination of eukaryotic host cell proteins has recently been identified as a novel post-translational modification important for bacterial pathogenesis. Here, we describe the first straightforward synthetic strategy for peptides containing phosphocholinated serine, threonine, or tyrosine residues using preformed functional amino acid building blocks, fully compatible with standard Fmoc solid-phase peptide synthesis.

  • 5.
    Albers, Michael F
    et al.
    Department of Chemical Biology, Max-Planck Institute of Molecular Physiology.
    van Vliet, Bart
    Hedberg, Christian
    Amino acid building blocks for efficient Fmoc solid-phase synthesis of peptides adenylylated at serine or threonine2011Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 13, nr 22, s. 6014-6017Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first straightforward building block based (non-interassembly) synthesis of peptides containing adenylylated serine and threonine residues is described. Key features include final global acidolytic protective group removal as well as full compatibility with standard Fmoc solid-phase peptide synthesis (SPPS). The described Thr-AMP SPPS-building block has been employed in the synthesis of the Thr-adenylylated sequence of human GTPase CDC42 (Ac-SEYVP-T(AMP)-VFDNYGC-NH(2)). Further, we demonstrate proof-of-concept for the synthesis of an Ser-adenylylated peptide (Ac-GSGA-S(AMP)-AGSGC-NH(2)) from the corresponding adenylylated serine building block.

  • 6.
    Albers, Michael Franz
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis and investigation of bacterial effector molecules2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    During infections, bacterial microorganisms initiate profound interactions with mammalian host cells. Usually defense mechanisms of the host destroy intruding bacteria in rapid manner. However, many bacterial pathogens have evolved in a way to avoid these mechanisms. By use of effector molecules, which can be small organic molecules or proteins with enzymatic activity, the host is manipulated on a molecular level. Effectors mediating post-translational modifications (PTMs) are employed by many pathogens to influence the biological activity of host proteins. In the presented thesis, two related PTMs are investigated in detail: Adenylylation, the covalent transfer of an adenosine monophosphate group from adenosine triphosphate onto proteins, and phosphocholination, the covalent transfer of a phosphocholine moiety onto proteins. Over the past years, enzymes mediating these modifications have been discovered in several pathogens, especially as a mechanism to influence the signaling of eukaryotic cells by adenylylating or phosphocholinating small GTPases. However, the development of reliable methods for the isolation and identification of adenylylated and phosphocholinated proteins remains a vehement challenge in this field of research. This thesis presents general procedures for the synthesis of peptides carrying adenylylated or phosphocholinated tyrosine, threonine and serine residues. From the resulting peptides, mono-selective polyclonal antibodies against adenylylated tyrosine and threonine have been raised. The antibodies were used as tools for proteomic research to isolate unknown substrates of adenylyl transferases from eukaryotic cells. Mass spectrometric fragmentation techniques have been investigated to ease the identification of adenylylated proteins. Furthermore, this work presents a new strategy to identify adenylylated proteins. Additionally, small effector molecules are involved in the regulation of infection mechanisms. In this work, the small molecule LAI-1 (Legionella autoinducer 1) from the pathogen Legionella pneumophila, the causative agent of the Legionnaire’s disease, was synthesised together with its amino-derivatives. LAI-1 showed are a clear pharmacological effect on the regulation of the life cycle of L. pneumophila, initiating transmissive traits like motility and virulence. Furthermore, LAI-1 was shown to have an effect on eukaryotic cells as well. Directed motility of the eukaryotic cells was significantly reduced and the cytoskeletal architecture was reorganised, probably by interfering with the small GTPase Cdc42.

  • 7. Almroth, Bethanie M. Carney
    et al.
    Gunnarsson, Lina M.
    Cuklev, Filip
    Fick, Jerker
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kristiansson, Erik
    Larsson, D. G. Joakim
    Waterborne beclomethasone dipropionate affects the physiology of fish while its metabolite beclomethasone is not taken up2015Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 511, s. 37-46Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Asthma is commonly treated with inhalable glucocorticosteroids, including beclomethasone dipropionate (BDP). This is a synthetic prodrug which is metabolized to the more active monopropionate (BMP) and free beclomethasone in humans. To evaluate potential effects of residual drugs on fish, we conducted a 14 day flow-through exposure experiment with BDP and beclomethasone using rainbow trout, and analyzed effects on plasma glucose, hepatic glutathione and catalase activity together with water and body concentrations of the BDP, BMP and beclomethasone. We also analyzed hepatic gene expression in BDP-exposed fish by micro-array and quantitative PCR Beclomethasone (up to 0.65 mu g/L) was not taken up in the fish while BDP (0.65 and 0.07 mu g/L) resulted in accumulation of both beclomethasone, BMP and BDP in plasma, reaching levels up to those found in humans during therapy. Accordingly, exposure to 0.65 mu g/L of BDP significantly increased blood glucose as well as oxidized glutathione levels and catalase activity in the liver. Exposure to beclomethasone or the low concentration of BDP had no effect on these endpoints. Both exposure concentrations of BDP resulted in significantly higher transcript abundance of phosphoenolpyruvate carboxykinase involved in gluconeogenesis, and of genes involved in immune responses. As only the rapidly metabolized prodrug was potent in fish, the environmental risks associated with the use of BDP are probably small. However, the observed physiological effects in fish of BDP at plasma concentrations known to affect human physiology provides valuable input to the development of read-across approaches in the identification of pharmaceuticals of environmental concern.

  • 8.
    Andersson, Barbro
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten.
    Analysis of plant growth regulating substances1982Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Natural plant growth regulators (phytohormones) are a group of organic compounds which, in very small amounts, act as regulators of physiological processes in plants.Methods were developed for the analysis of phytohormones in samples from Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris (L.) Karst»). Identification of abscisic acid, 3-indoleacetic acid, gibbe-rellin Ag and the conjugate N-(3-indoleacetyl)aspartic acid was performed by GC-MS as their methyl esters. A quantitative determination of abscisic acid was made by GC-ECD and this method was also applied to anther samples of Anemone canadensis. 3-Indole-acetic acid and N-(3-indoleacetyl)aspartic acid were quantified by reversed-phase HPLC and spectrofluorimetric detection. Dichlorophene, used as a growth regulator in containerized seedlings of pine and spruce, was analysed by GC-MID in peat and paper.

  • 9.
    Andersson, David C.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Martinez, N.
    Zeller, D.
    Rondahl, S. H.
    Koza, M. M.
    Frick, B.
    Ekstrom, F.
    Peters, J.
    Linusson, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Changes in dynamics of alpha-chymotrypsin due to covalent inhibitors investigated by elastic incoherent neutron scattering2017Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, nr 37, s. 25369-25379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An essential role of enzymes is to catalyze various chemical reactions in the human body and inhibition of the enzymatic activity by small molecules is the mechanism of action of many drugs or tool compounds used to study biological processes. Here, we investigate the effect on the dynamics of the serine protease alpha-chymotrypsin when in complex with two different covalently bound inhibitors using elastic incoherent neutron scattering. The results show that the inhibited enzyme displays enhanced dynamics compared to the free form. The difference was prominent at higher temperatures (240-310 K) and the type of motions that differ include both small amplitude motions, such as hydrogen atom rotations around a methyl group, and large amplitude motions, such as amino acid side chain movements. The measurements were analyzed with multivariate methods in addition to the standard univariate methods, allowing for a more in-depth analysis of the types of motions that differ between the two forms. The binding strength of an inhibitor is linked to the changes in dynamics occurring during the inhibitor-enzyme binding event and thus these results may aid in the deconvolution of this fundamental event and in the design of new inhibitors.

  • 10.
    Andersson, Hans
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Reaction Between Grignard reagents and Heterocyclic N-oxides: Synthesis of Substituted Pyridines, Piperidines and Piperazines2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the development of new synthetic methodologies for preparation of bioactive interesting compounds, e.g. substituted pyridines, piperidines or piparazines. Thesecompounds are synthesized from commercially available, cheap and easily prepared reagents, videlicet the reaction between Grignard reagents and heterocyclic N-oxides.

     The first part of this thesis deals with an improvement for synthesis of dienal-oximes and substituted pyridines. This was accomplished by a rapid addition of Grignard reagents to pyridine N-oxides at rt. yielding a diverse set of substituted dienal-oximes. During these studies, it was observed that the obtained dienal-oxmies are prone to ring-close upon heating. By taking advantage of this, a practical synthesis of substituted pyridines was developed.

    In the second part, an ortho-metalation of pyridine N-oxides using Grignard reagents is discussed. The method can be used for incorporation of a range of different electrophiles, including aldehydes, ketones and halogens. Furthermore, the importance for incorporation of halogens are exemplified through a Suzuki–Miyaura coupling reaction of 2-iodo pyridine N-oxides and different boronic acids. Later it was discovered that if the reaction temperature is kept below -20 °C, the undesired ringopening can be avoided. Thus, the synthesis of 2,3-dihydropyridine N-oxide, by reacting Grignard reagents with pyridine N-oxides at -40 °C followed by sequential addition of aldehyde or ketone, was accomplished. The reaction provides complete regio- and stereoselectivity yielding trans-2,3-dihydropyridine N-oxides in good yields. These intermediate products could then be used for synthesis of either substituted piperidines, by reduction, or reacted in a Diels–Alder cycloaddtion to give the aza-bicyclo compound.

    In the last part of this thesis, the discovered reactivity for pyridine N-oxides, is applied on pyrazine N-oxides in effort to synthesize substituted piperazines. These substances are obtained by the reaction of Grignard reagents and pyrazine N-oxides at -78 °C followed by reduction and protection, using a one-pot procedure. The product, a protected piperazine, that easily can be orthogonally deprotected, allowing synthetic modifications at either nitrogens in a fast and step efficient manner. Finally, an enantioselective procedure using a combination of PhMgCl and (-)-sparteine is discussed, giving opportunity for a stereoselective synthesis of substituted piperazines.

  • 11.
    Andersson, Ida E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Modified Glycopeptides Targeting Rheumatoid Arthritis: Exploring molecular interactions in class II MHC/glycopeptide/T-cell receptor complexes2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that leads to degradation of cartilage and bone mainly in peripheral joints. In collagen-induced arthritis (CIA), a mouse model for RA, activation of autoimmune CD4+ T cells depends on a molecular recognition system where T-cell receptors (TCRs) recognize a complex between the class II MHC Aq protein and CII259-273, a glycopeptide epitope from type II collagen (CII). Interestingly, vaccination with the Aq/CII259-273 complex can relieve symptoms and cause disease regression in mice. This thesis describes the use of modified glycopeptides to explore interactions important for binding to the Aq protein and recognition by autoimmune T-cell hybridomas obtained from mice with CIA.

    The CII259-273 glycopeptide was modified by replacement of backbone amides with different amide bond isosteres, as well as substitution of two residues that anchor the glycopeptide in prominent pockets in the Aq binding site. A three-dimensional structure of the Aq/glycopeptide complex was modeled to provide a structural basis for interpretation of the modified glycopeptide’s immunological activities. Overall, it was found that the amide bond isosteres affected Aq binding more than could be explained by the static model of the Aq/glycopeptide complex. Molecular dynamics (MD) simulations, however, revealed that the introduced amide bond isosteres substantially altered the hydrogen-bonding network formed between the N-terminal 259-265 backbone sequence of CII259-273 and Aq. These results indicated that the N-terminal hydrogen-bonding interactions follow a cooperative model, where the strength and presence of individual hydrogen bonds depended on the neighboring interactions.

    The two important anchor residues Ile260 and Phe263 were investigated using a designed library of CII259-273 based glycopeptides with substitutions by different (non-)natural amino acids at positions 260 and 263. Evaluation of binding to the Aq protein showed that there was scope for improvement in position 263 while Ile was preferred in position 260. The obtained SAR understanding provided a valuable basis for future development of modified glycopeptides with improved Aq binding. Furthermore, the modified glycopeptides elicited varying T-cell responses that generally could be correlated to their ability to bind to Aq. However, in several cases, there was a lack of correlation between Aq binding and T-cell recognition, which indicated that the interactions with the TCRs were determined by other factors, such as presentation of altered epitopes and changes in the kinetics of the TCR’s interaction with the Aq/glycopeptide complex.

    Several of the modified glycopeptides were also found to bind well to the human RA-associated DR4 protein and elicit strong responses with T-cell hybridomas obtained from transgenic mice expressing DR4 and the human CD4 co-receptor. This encourages future investigations of modified glycopeptides that can be used to further probe the MHC/glycopeptide/TCR recognition system and that also constitute potential therapeutic vaccines for treatment of RA. As a step towards this goal, three modified glycopeptides presented in this thesis have been identified as candidates for vaccination studies using the CIA mouse model.

  • 12. Asgari, Parham
    et al.
    Hua, Yuanda
    Bokka, Apparao
    Thiamsiri, Chanachon
    Prasitwatcharakorn, Watcharapon
    Karedath, Ashif
    Chen, Xin
    Sardar, Sinjinee
    Yum, Kyungsuk
    Leem, Gyu
    Pierce, Brad S.
    Nam, Kwangho
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gao, Jiali
    Jeon, Junha
    Catalytic hydrogen atom transfer from hydrosilanes to vinylarenes for hydrosilylation and polymerization2019Inngår i: Nature Catalysis, ISSN 2520-1158, Vol. 2, nr 2, s. 164-173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Because of the importance of hydrogen atom transfer (HAT) in biology and chemistry, there is increased interest in new strategies to perform HAT in a sustainable manner. Here, we describe a sustainable, net redox-neutral HAT process involving hydrosilanes and alkali metal Lewis base catalysts-eliminating the use of transition metal catalysts-and report an associated mechanism concerning Lewis base-catalysed, complexation-induced HAT. The catalytic Lewis base-catalysed, complexation-induced HAT is capable of accessing both branch-specific hydrosilylation and polymerization of vinylarenes in a highly selective fashion, depending on the Lewis base catalyst used. In this process, the Earth-abundant, alkali metal Lewis base catalyst plays a dual role. It first serves as a HAT initiator and subsequently functions as a silyl radical stabilizing group, which is critical to highly selective cross-radical coupling. An electron paramagnetic resonance study identified a potassiated paramagnetic species, and multistate density functional theory revealed a high HAT character, yet multiconfigurational nature in the transition state of the reaction.

  • 13.
    Badea, Silviu-Laurentiu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Danet, Andrei-Florin
    Enantioselective stable isotope analysis (ESIA) - A new concept to evaluate the environmental fate of chiral organic contaminants2015Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 514, s. 459-466Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Since 2011, the enantiospecific stable carbon isotope analysis (ESIA) has emerged as an innovative technique to assess the environmental fate of chiral emerging compounds by combining in one experimental technique both compound specific isotope analysis (CSIA) and enantioselective analysis. To date, the ESIA was applied for four classes of compounds: alpha-hexachlorocyclohexane (alpha-HCH), polar herbicides (phenoxy acids), synthetic polycyclic musk galaxolide (HHCB), and phenoxyalkanoic methyl herbicides. From an analytical point of view there are factors that are hindering the application of ESIA methods for the field samples: (i.e. amounts of target analyte, matrix effects, GC resolution) and overcoming these factors is challenging. While ESIA was shown as a mature technique for the first three abovementioned class of compounds, no isotope analysis of individual enantiomers could be performed for phenoxyalkanoic methyl herbicides. With respect to field studies, one study showed that ESIA might be a promising tool to distinguish between biotic and abiotic transformation pathways of chiral organic contaminants and even to differentiate between their aerobic and anaerobic biotransformation pathways. The development of ESIA methods for new chiral emerging contaminants in combination with development of multi-element isotope analysis will contribute to a better characterization of transformation pathways of chiral organic contaminants. (C) 2015 Elsevier B.V. All rights reserved.

  • 14.
    Barange, Deepak Kumar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Johnson, Magnus T.
    Cairns, Andrew G.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Olsson, Roger
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Regio- and Stereoselective Alkylation of Pyridine-N-oxides: Synthesis of Substituted Piperidines and Pyridines2016Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 18, nr 24, s. 6228-6231Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Regio- and stereoselective addition of alkyl Grignard reagents to pyridine-N-oxides gave C2-alkylated N-hydroxy-1,2,5,6-tetrahydropyridines and trans-2,3-disubstituted N-hydroxy-1,2,5,6-tetrahydropyridines in good to excellent yields. These intermediates were aromatized or alternatively reduced in one-pot methodologies for efficient syntheses of alkylpyridines or piperidines, respectively. These reactions have a broad substrate scope and short reaction times.

  • 15.
    Barzegar, Hamid Reza
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Nitze, Florian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Malolepszy, Artur
    Stobinski, Leszek
    Tai, Cheuk-Wai
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Water assisted growth of C-60 rods and tubes by liquid-liquid interfacial precipitation method2012Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 17, nr 6, s. 6840-6853Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    C-60 nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C-60/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C-60 tubes where both length and diameter of the C-60 tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C-60 rods and tubes based on the diffusion rate of the good C-60 containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 degrees C at a pressure <1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.

  • 16. Basu, Basudeb
    et al.
    Paul, Susmita
    Kundu, Samir
    Byström, Emil
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Organic Polymeric Resins Embedded with Pd NPs: Newly Designed, Efficient and Chemoselective Catalyst for Reduction of Nitrobenzenes2017Inngår i: Current Organocatalysis, ISSN 2213-3372, Vol. 4, nr 1, s. 48-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Organic polymer supported palladium nanoparticles (NPs) are important for use as heterogeneous catalyst in various organic reactions. This works describes Pd Nps immobilized on to polystyrene-based ion-exchange resin surface for use as catalyst in the reduction of nitrobenzenes. The heterogeneous catalyst was found useful for hydrogenation of nitro group under both catalytic transfer hydrogenation (CTH) as well as by using molecular hydrogen (H2).

    Methods: The catalyst was prepared from Amberlite IRA 900 Cl after rinsing with formic acid (10%) and subsequent treatment with Na2PdCl4 in DMF. The resulting Pd Nps immobilized resins was designated as VersaCat Pd and used for CTH of nitrobenzenes in the presence of H-donors (sodium formate, formic acid, hydrazine hydrate) and also for hydrogenation with H2 gas. The catalyst was characterized by FT-IR, MAS-NMR, SEM, TEM and XPS and surface morphologies were studied before and after the reaction.

    Results: Hydrogenations of nitrobenzenes under CTH using different H-source and direct use of H2 gas were achieved successfully with good to excellent yields. Reactions were performed under mild conditions and high degree of chemoselectivity was also observed. The catalyst was recyclable, used for six consecutive runs with appreciable conversions and showed higher activity (> 3 times) in terms of metalcontent than commercially available Pd/C (10%) in the hydrogenation of nitrobenzenes using H2 gas. The TEM images showed that Pd Nps are evenly distributed with size 50-200 mm on polymeric matrices and there was no significant changes observed after the first catalytic run. However, considerable rupture of the polymeric surface occurred after six runs, as seen from SEM studies.

    Conclusion: The present study establishes high catalytic efficiency and chemoselectivity of the newly developed organic polystyrene-based resin-soaked Pd NPs (VersaCat Pd) in the reduction of nitrobenzenes. Both CTH and hydrogenation using H2 gas were successfully done. Interestingly, hydrazine hydrate offered excellent control over chemoselectivity under CTH conditions and allowed clean conversion from nitro to amine, while keeping a chloro substitutent unaffected. Hydrogenation using molecular H2 gave maximum TOF. Easy preparation, high efficacy, TOF, chemoselectivity, and versatile applications are notable features for this heterogeneous palladium catalyst (VersaCat Pd). These features are often required in chemical industries.

  • 17.
    Berglin, Ewa
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Edlund, Maj-Britt K.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Nyberg, Göran K.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Carlsson, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli1982Inngår i: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 152, nr 1, s. 81-88Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

  • 18.
    Berglin, Ewa H.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Carlsson, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Oral mikrobiologi.
    Potentiation by sulfide of hydrogen peroxide-induced killing of Escherichia coli1985Inngår i: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 49, nr 3, s. 538-543Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    L-Cysteine potentiates 100-fold the hydrogen peroxide-induced killing of a growing culture of Escherichia coli K-12 (Berglin et al., J. Bacteriol. 152:81-88). In the present study it is shown that hydrogen sulfide is formed from L-cysteine and that sodium sulfide could substitute for L-cysteine in the potentiation of hydrogen peroxide-induced killing of E. coli K-12. Addition of an amino acid, L-leucine, L-valine, or L-alanine, to an L-cysteine-containing medium with a growing culture of E. coli K-12 inhibited hydrogen sulfide formation and the potentiation of hydrogen peroxide-induced killing. These amino acids did not inhibit hydrogen sulfide formation from L-cysteine by a cell extract, and they did not inhibit the potentiation by sulfide of hydrogen peroxide-induced killing. This indicated that the amino acids protected the culture from L-cysteine-potentiated, hydrogen peroxide-induced killing by inhibiting the transport of L-cysteine into the cell. The potentiation by sodium sulfide of hydrogen peroxide-induced killing was abolished by the metal ion chelator 2,2'-bipyridyl. This indicated that metal ions, in addition to sulfide, were involved in the killing. Toxic effects of hydrogen peroxide are often presumed to be mediated by hydroxyl radicals formed in iron-catalyzed reactions. It was demonstrated that iron sulfide was more efficient than ferrous iron in catalyzing the formation of hydroxyl radicals from hydrogen peroxide. It was suggested that hydrogen sulfide formed in polymicrobial infections may play an important role in the host defense by potentiating the antimicrobial effect of hydrogen peroxide produced by phagocytic cells.

  • 19.
    Bergqvist, Per-Anders
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Zaliauskiene, Audrone
    Field study considerations in the use of passive sampling devices in water monitoring2007Inngår i: Passive Sampling Techniques in Environmental Monitoring / [ed] R. Greenwood, G. Mills and B. Vrana, Amsterdam: Elsevier, 2007, s. 311-328Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Semipermeable membrane devices (SPMDs) are passive monitors that are being increasingly used by monitoring agencies and wastewater dischargers to measure the contents of lipophilic organic chemicals that may adversely affect water quality. This chapter addresses the most frequently asked questions regarding the use of SPMDs for water monitoring and other questions related to the field application of SPMDs. It provides a sound understanding of the applicability and limitations of SPMDs for obtaining reliable monitoring data. The chapter discusses under field study considerations: pre-exposure considerations; SPMD storage considerations; and precautions/procedures during deployment and retrieval of SPMDs. In environmental monitoring projects using SPMDs, quality control (QC) procedures for sampling and analysis are applied to ensure that the data are of high quality. Appropriate QC samples are prepared to quantify possible sampler contamination during transport, deployment, retrieval, storage, processing, enrichment, fractionation operations and analyte recovery. In general, two groups of quality assurance measures are implemented: replicate QC and sampling device control.

  • 20. Bernardo-Garcia, Noelia
    et al.
    Sánchez-Murcia, Pedro A.
    Espaillat, Akbar
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Martínez-Caballero, Siseth
    Cava, Felipe
    Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Hermoso, Juan A.
    Gago, Federico
    Cold-induced aldimine bond cleavage by Tris in Bacillus subtilis alanine racemase2019Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 17, nr 17, s. 4350-4358Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pyridoxal 5'-phosphate (PLP) is a versatile cofactor involved in a large variety of enzymatic processes. Most of PLP-catalysed reactions, such as those of alanine racemases (AlaRs), present a common resting state in which the PLP is covalently bound to an active-site lysine to form an internal aldimine. The crystal structure of BsAlaR grown in the presence of Tris lacks this covalent linkage and the PLP cofactor appears deformylated. However, loss of activity in a Tris buffer only occurred after the solution was frozen prior to carrying out the enzymatic assay. This evidence strongly suggests that Tris can access the active site at subzero temperatures and behave as an alternate racemase substrate leading to mechanism-based enzyme inactivation, a hypothesis that is supported by additional X-ray structures and theoretical results from QM/ MM calculations. Taken together, our findings highlight a possibly underappreciated role for a common buffer component widely used in biochemical and biophysical experiments.

  • 21. Bhattacharjee, Snehasish
    et al.
    Chakraborty, Sandipan
    Chorell, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sengupta, Pradeep K.
    Bhowmik, Sudipta
    Importance of the hydroxyl substituents in the B-ring of plant flavonols on their preferential binding interactions with VEGF G-quadruplex DNA: Multi-spectroscopic and molecular modeling studies2018Inngår i: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 118, s. 629-639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    G-quadruplex (G4) structures are known to be promising anticancer drug targets and flavonols (an important class of fiavonoids) are small molecules reported to possess several health-promoting properties including those of anticancer activities. In this work, we explored the interactions of the structurally related plant flavonols kaempferol (KAE; 3,5,7,4'-OH flavone) and morin (MOR; 3,5,7,2',4'-OH flavone) with various G4-DNA sequences along with duplex DNA using a combination of spectroscopic and molecular docking studies. Our results revealed that KAE shows preferential interaction with VEGF G4-DNA in comparison to the other G4 sequences and duplex DNA. Moreover, KAE enhances the thermal stability of VEGF G4-DNA. In contrast, MOR exhibits an appreciably weaker level of interaction with both duplex and various G4-DNAs, with no significant structural specificity. The contrasting DNA binding behaviors suggest a crucial role of the 2'-OH substituent in the Bring of flavonol moiety. While KAE is relatively planar, MOR adopts a significantly non-planar conformation attributable to steric hindrance from the additional 2'-OH substituent. This small structural difference is apparently very important for the ability of KAE and MOR to interact with VEGF G4-DNA. Thus, KAE (but not MOR) appears to be an effective ligand for VEGF G4-DNA, opening up possibilities of its application for regulation of gene expression in cancer cells. 

  • 22.
    Bidleman, Terry Frank
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Air Quality Processes Research Section, Environment Canada.
    Jantunen, L. M.
    Hung, H.
    Ma, J.
    Stern, G. A.
    Rosenberg, B.
    Racine, J.
    Annual cycles of organochlorine pesticide enantiomers in Arctic air suggest changing sources and pathways2015Inngår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, nr 3, s. 1411-1420Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Air samples collected during 1994-2000 at the Canadian Arctic air monitoring station Alert (82 degrees 30'N, 62 degrees 20'W) were analysed by enantiospecific gas chromatography-mass spectrometry for alpha-hexachlorocyclohexane (alpha-HCH), trans-chlordane (TC) and cis-chlordane (CC). Results were expressed as enantiomer fractions (EF = peak areas of (+)/[(+) + (-)] enantiomers), where EFs = 0.5, <0.5 and >0.5 indicate racemic composition, and preferential depletion of (+) and (-) enantiomers, respectively. Long-term average EFs were close to racemic values for alpha-HCH (0.504 +/- 0.004, n = 197) and CC (0.505 +/- 0.004, n = 162), and deviated farther from racemic for TC (0.470 +/- 0.013, n = 165). Digital filtration analysis revealed annual cycles of lower alpha-HCH EFs in summer-fall and higher EFs in winter-spring. These cycles suggest volatilization of partially degraded alpha-HCH with EF < 0.5 from open water and advection to Alert during the warm season, and background transport of alpha-HCH with EF > 0.5 during the cold season. The contribution of sea-volatilized alpha-HCH was only 11% at Alert, vs. 32% at Resolute Bay (74.68 degrees N, 94.90 degrees W) in 1999. EFs of TC also followed annual cycles of lower and higher values in the warm and cold seasons. These were in phase with low and high cycles of the TC / CC ratio (expressed as F-TC = TC/(TC + CC)), which suggests greater contribution of microbially "weathered" TC in summer-fall versus winter-spring. CC was closer to racemic than TC and displayed seasonal cycles only in 1997-1998. EF profiles are likely to change with rising contribution of secondary emission sources, weathering of residues in the environment, and loss of ice cover in the Arctic. Enantiomer-specific analysis could provide added forensic capability to air monitoring programs.

  • 23.
    Blomberg, David
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Synthesis of β-turn and pyridine based peptidomimetics2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Despite the unfavorable pharmacokinetic properties associated with peptides, they are still of great interest in drug development due to a multitude of interesting biological functions. The development of peptidomimetics strives to maintain or improve the biological activity of a peptide concurrently with removing the unwanted properties. This thesis describes two synthetic approaches to peptidomimetics with particular emphasis on secondary structure mimetics.

    First the design, synthesis and evaluation of two beta-turn mimetics incorporated in the endorphin Leu-enkephalin is presented. The beta-turn mimetics were stabilized by replacement of the intramolecular hydrogen bond with an ethylene bridge, and the amide bond between Tyr and Gly was replaced with an ether linkage. Linear analogues of the two mimetics were also synthesized. The peptidomimetics and their linear analogues were evaluated in a competitive binding assay at two opiate receptors, my and delta. One of the cyclized beta-turn mimetics was found to be a delta receptor antagonist with an IC50 value of 160 nM.

    Second a synthetic strategy to a beta-strand mimetic using 2-fluoro-4-iodopyridine as scaffold is described. The synthesis involved a Grignard exchange reaction on the pyridine scaffold using an amino acid derivative as electrophile followed by an SNAr reaction using an amine as nucleophile. The synthesis of a tripeptidomimetic of Leu-Gly-Gly and attempts to introduce chiral building blocks at the C-terminal, as well as studies towards elongated mimetics are presented.

    Two additional studies deal with the synthesis of two classes of potential thrombin inhibitors based on the pyridine scaffold. The first class contain pyridine as central fragment (P2 residue) substituted with a para-amidinobenzylamine group as P1 residue and various benzoyl groups as P3 residues. Three potential thrombin inhibitors were synthesized and found to be microM inhibitors in an enzymatic assay. In the second class, the pyridine ring serves as P3 residue. This class also lacks a strongly basic group in the P1 position. A small library of eight compounds were synthesized and evaluated in the enzymatic assay. Unfortunately, these compounds lacked inhibitory activity.

  • 24. Borah, Raju Kumar
    et al.
    Raul, Prasanta Kumar
    Mahanta, Abhijit
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Åbo Akademi University, Åbo-Turku, Finland.
    Thakur, Ashim Jyoti
    Copper Oxide Nanoparticles as a Mild and Efficient Catalyst for N-Arylation of Imidazole and Aniline with Boronic Acids at Room Temperature2017Inngår i: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, Vol. 28, nr 10, s. 1177-1182Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present work describes the excellent catalytic activity of copper(II) oxide nanoparticles (NPs) towards N-arylation of aniline and imidazole at room temperature. The copper(II) oxide NPs were synthesized by a thermal refluxing technique and characterized by FT-IR spectroscopy; powder XRD, SEM, EDX, TEM, TGA, XPS, BET surface area analysis, and particle size analysis. The size of the NPs was found to be around 12 nm having a surface area of 164.180 m(2) g(-1). The catalytic system was also found to be recyclable and could be reused in subsequent catalytic runs without a significant loss of activity.

  • 25. Bui, Hue T B
    et al.
    Vo, Duy D
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Chau, Yen N T
    Tu, Cuc T K
    Mai, Hieu V
    Truong, Kiet V
    Facile Synthesis of 4-Oxo-4H-quinolizine-2-carboxamide Derivatives2015Inngår i: Synthetic Communications, ISSN 0039-7911, E-ISSN 1532-2432, Vol. 45, nr 24, s. 2861-2868Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A facile synthetic method for the construction of 2-substituted-4-oxo-4H-quinolizine-based core structure has been successfully developed. The synthesis made use of a one-pot Stobbe condensation followed by cyclization starting from the commercially available 2-pyridinecarbaldehyde. The structure of the formed 4-oxo-4H-quinolizine-2-carboxylate was fully confirmed by mass spectra, H-1 NMR and C-13 NMR, correlation spectrography, heteronuclear multiple bond correlation, and heteronuclear single quantum coherence (HSQC) spectra. The ethyl carboxylate moiety was then further functionalized via direct aminolysis by a range of amines to afford the corresponding 4-oxo-4H-quinolizine-2-carboxamides 4a-i in moderate to good yields.

  • 26. Bui, Hue Thi Buu
    et al.
    Ha, Quy Thi Kim
    Oh, Won Keun
    Vo, Duy Duc
    Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chau, Yen Nguyen Tram
    Tu, Cuc Thi Kim
    Pham, Em Canh
    Tran, Phuong Thao
    Tran, Loan Thi
    Mai, Hieu Van
    Microwave assisted synthesis and cytotoxic activity evaluations of new benzimidazole derivatives2016Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 57, nr 8, s. 887-891Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Twelve new 2-quinolizinylbenzimidazole and 2-naphthalylbenzimidazole derivatives with various 5- and 6-positioned substituents (aza, H, CH3, Cl, NO2, NH2, OCH3), have been synthesized in moderate to excellent yields via the condensation of 4-oxo-4H-quinolizinecarbaldehyde or naphthalenecarbaldehyde with substituted o-phenylenediamines, o-nitroaniline, and 2,3-pyridinediamine using sodium metabisulfite or sodium hydrosulfite under microwave irradiation. The new benzimidazole derivatives were screened for their cytotoxic activity against the human breast cancer cell line (MCF-7). The results showed on one hand that 2-(substituted quinolizinyl)-1H-benzimidazoles (12bf) were less active (3–6 fold) than the positive control Tamoxifen (CC50 = 6.52 μM), and on the other hand, among the 2-(substituted naphthalyl)-1H-benzimidazoles series (13af), compounds 6,7,8-trimethoxy-3-(5-chloro-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13c) (CC50 = 7.48 μM) and 6,7,8-trimethoxy-3-(5-methoxy-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13f) (CC50 = 6.43 μM) were found to be as active as Tamoxifen.

  • 27.
    Cairns, Andrew G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Vazquez-Romero, Ana
    Mahdi-Moein, Mohammad
    Ådén, Jörgen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Elmore, Charles S.
    Takano, Akihiro
    Arakawa, Ryosuke
    Varrone, Andrea
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Schou, Magnus
    Increased Brain Exposure of an Alpha-Synuclein Fibrillization Modulator by Utilization of an Activated Ester Prodrug Strategy2018Inngår i: ACS Chemical Neuroscience, ISSN 1948-7193, E-ISSN 1948-7193, Vol. 9, nr 11, s. 2542-2547Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous work in our laboratories has identified a series of peptidomimetic 2-pyridone molecules as modulators of alpha-synuclein (α-syn) fibrillization in vitro. As a first step toward developing molecules from this scaffold as positron emission tomography imaging agents, we were interested in evaluating their blood-brain barrier permeability in nonhuman primates (NHP) in vivo. For this purpose, 2-pyridone 12 was prepared and found to accelerate α-syn fibrillization in vitro. Acid 12, and its acetoxymethyl ester analogue 14, were then radiolabeled with 11C (t1/2 = 20.4 min) at high radiochemical purity (>99%) and high specific radioactivity (>37 GBq/μmol). Following intravenous injection of each compound in NHP, a 4-fold higher radioactivity in brain was observed for [11C]14 compared to [11C]12 (0.8 vs 0.2 SUV, respectively). [11C]14 was rapidly eliminated from plasma, with [11C]12 as the major metabolic product observed by radio-HPLC. The presented prodrug approach paves the way for future development of 2-pyridones as imaging biomarkers for in vivo imaging of α-synuclein deposits in brain.

  • 28.
    Carlsson, Marcus
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Synthesis and optical characterization of optical power limiting platinum(II) acetylides2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Interactions between light and a molecule can result in reversible or irreversible changes in properties of both the light and the molecule. Of the many known interactions, nonlinear absorption is a process in which an intense light signal, for instance from a laser, can be moderated. This can be manifested either in a marked lowering of the light’s intensity or in reductions in fluctuations of its intensity. Such an effect is often termed ‘optical power limiting’ (OPL).

    High power lasers can be very dangerous since their high intensity can damage or destroy eyes and optical sensors. However, there are currently no adequate protective measures against lasers that cover the entire visible region and there is an increasing demand for new or improved OPL materials. Some of the most promising optical power limiting materials are substances that combine nonlinear optical properties with high transparency in normal light, but after activation by a laser beam, their light transmittance falls extremely rapidly via so-called self-activating mechanisms. The platinum(II) acetylides comprise one class of compounds with such properties.

    In this study, various OPL Pt(II) acetylides were synthesized and their nonlinear optical properties were characterized. The emphasis of the work was on preparation of the compounds, but in order to design organoplatinum chromophores for OPL, attempts were also made to obtain insight into the mechanisms of nonlinear absorption.

    The work was divided into two main parts. In the first the goal was to find compounds that are good optical limiters in solution. The possibility of isolating the chromophore site by dendron shielding and the effects of incorporating a thiophene ring into the organic molecular system were also explored. In addition, a new route for synthesizing these compounds was developed. The second part was focused on incorporating the most interesting compounds into solid materials. The preparation and characterization of Pt(II) acetylides with molecular groups for covalent attachment to a silica matrix via the solution gel approach is described.

  • 29. Chen, Xi
    et al.
    Venkatachalapathy, Muthukumaran
    Kamps, Dominic
    Weigel, Simone
    Kumar, Ravi
    Orlich, Michael
    Garrecht, Ruben
    Hirtz, Michael
    Niemeyer, Christof M.
    Wu, Yao-Wen
    Chemical Genomics Centre of the Max-Planck Society, Dortmund, Germany.
    Dehmelt, Leif
    “Molecular Activity Painting”: Switch-like, light-controlled perturbations inside living cells2017Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, nr 21, s. 5916-5920Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Acute subcellular protein targeting is a powerful tool to study biological networks. However, signaling at the plasma membrane is highly dynamic, making it difficult to study in space and time. In particular, sustained local control of molecular function is challenging due to lateral diffusion of plasma membrane targeted molecules. Here we present “Molecular Activity Painting” (MAP), a novel technology which combines photoactivatable chemically induced dimerization (pCID) with immobilized artificial receptors. The immobilization of artificial receptors by surface-immobilized antibodies blocks lateral diffusion, enabling rapid and stable “painting” of signaling molecules and their activity at the plasma membrane with micrometer precision. Using this method, we show that painting of the RhoA-myosin activator GEF-H1 induces patterned acto-myosin contraction inside living cells.

  • 30.
    Cheregi, Otilia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Regulation of the scp Genes in the Cyanobacterium Synechocystis sp PCC 6803-What is New?2015Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 20, nr 8, s. 14621-14637Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the cyanobacterium Synechocystis sp. PCC 6803 there are five genes encoding small CAB-like (SCP) proteins, which have been shown to be up-regulated under stress. Analyses of the promoter sequences of the scp genes revealed the existence of an NtcA binding motif in two scp genes, scpB and scpE. Binding of NtcA, the key transcriptional regulator during nitrogen stress, to the promoter regions was shown by electrophoretic mobility shift assay. The metabolite 2-oxoglutarate did not increase the affinity of NtcA for binding to the promoters of scpB and scpE. A second motif, the HIP1 palindrome 5' GGCGATCGCC 3', was detected in the upstream regions of scpB and scpC. The transcription factor encoded by sll1130 has been suggested to recognize this motif to regulate heat-responsive genes. Our data suggest that HIP1 is not a regulatory element within the scp genes. Further, the presence of the high light regulatory (HLR1) motif was confirmed in scpB-E, in accordance to their induced transcriptions in cells exposed to high light. The HLR1 motif was newly discovered in eight additional genes.

  • 31.
    Chorell, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pilicides and Curlicides: Design, synthesis, and evaluation of novel antibacterial agents targeting bacterial virulence2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    New strategies are needed to counter the growing problem of bacterial resistance to antibiotics. One such strategy is to design compounds that target bacterial virulence, which could work separately or in concert with conventional bacteriostatic or bactericidal antibiotics. Pilicides are a class of compounds based on a ring-fused 2-pyridone scaffold that target bacterial virulence by blocking the chaperone/usher pathway in E. coli and thereby inhibit the assembly of pili. This thesis describes the design, synthesis, and biological evaluation of compounds based on the pilicide scaffold with the goal of improving the pilicides and expanding their utility. Synthetic pathways have been developed to enable the introduction of substituents at the C-2 position of the pilicide scaffold. Biological evaluation of these compounds demonstrated that some C-2 substituents give rise to significant increases in potency. X-ray crystallography was used to elucidate the structural basis of this improved biological activity. Furthermore, improved methods for the preparation of oxygen-analogues and C-7 substituted derivatives of the pilicide scaffold have been developed. These new methods were used in combination with existing strategies to decorate the pilicide scaffold as part of a multivariate design approach to improve the pilicides and generate structure activity relationships (SARs).

    Fluorescent pilicides were prepared using a strategy where selected substituents were replaced with fluorophores having similar physicochemical properties as the original substituents. Many of the synthesized fluorescent compounds displayed potent pilicide activities and can thus be used to study the complex interactions between pilicide and bacteria. For example, when E. coli was treated with fluorescent pilicides, it was found that the compounds were not uniformly distributed throughout the bacterial population, suggesting that the compounds are primarily associated to bacteria with specific properties.

    Finally, by studying compounds designed to inhibit the aggregation of Aβ, it was found that some compounds based on the pilicide scaffold inhibit the formation of the functional bacterial amyloid fibers known as curli; these compounds are referred to as 'curlicides'. Some of the curlicides also prevent the formation of pili and thus exhibit dual pilicide-curlicide activity. The potential utility of such 'dual-action' compounds was highlighted by a study of one of the more potent dual pilicide-curlicides in a murine UTI model were the compound was found to significantly attenuate virulence in vivo.

  • 32.
    Chorell, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bengtsson, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sainte-Luce Banchelin, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Das, Pralay
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Uvell, Hanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sinha, Arun K
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pinkner, Jerome S
    Department of Molecular Microbiology, Washington University, School of Medicine, St. Louis, Missouri 63110, USA.
    Hultgren, Scott J
    Department of Molecular Microbiology, Washington University, School of Medicine, St. Louis, Missouri 63110, USA.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis and application of a bromomethyl substituted scaffold to be used for efficient optimization of anti-virulence activity2011Inngår i: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 46, nr 4, s. 1103-1116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pilicides are a class of compounds that attenuate virulence in Gram negative bacteria by blocking the chaperone/usher pathway in Escherichia coli. It has also been shown that compounds derived from the peptidomimetic scaffold that the pilicides are based on can prevent both Aβ aggregation and curli formation. To facilitate optimizations towards the different targets, a new synthetic platform has been developed that enables fast and simple introduction of various substituents in position C-7 on the peptidomimetic scaffold. Importantly, this strategy also enables introduction of previously unattainable heteroatoms in this position. Pivotal to the synthetic strategy is the synthesis of a C-7 bromomethyl substituted derivative of the ring-fused dihydrothiazolo 2-pyridone pilicide scaffold. From this versatile and reactive intermediate various heteroatom-linked substituents could be introduced on the scaffold including amines, ethers, amides and sulfonamides. In addition, carbon-carbon bonds could be introduced to the sp(3)-hybridized bromomethyl substituted scaffold by Suzuki-Miyaura cross couplings. Evaluation of the 24 C-7 substituted compounds in whole-bacterial assays provided important structure-activity data and resulted in the identification of a number of new pilicides with activity as good or better than those developed previously.

  • 33.
    Chorell, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chorell, Elin
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Efficient Synthesis of 2-Substituted Phthalimides from Phthalic Acids in One Step2013Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2013, nr 33, s. 7512-7516Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Efficient procedures for synthesizing 2-substituted phthalimide (isoindole-1,3-dione) analogues starting from phthalic acids have been developed by using experimental design. The phthalimide central fragment frequently appears in biologically active compounds, materials, catalysts, and fluorescent probes, and therefore the development of general, fast, and convenient synthetic methods to this scaffold under neutral, acidic, and basic conditions would be attractive. After an initial screening, the use of acetonitrile, acetic acid, or pyridine in combination with microwave heating proved most promising. Experimental design was applied to these conditions to optimize the time, temperature, and concentration. This strategy has successfully generated synthetic methods that have been used to synthesize a series of phthalimides from phthalic acids and various amines or anilines in excellent yields. The developed methods have proven to be general, fast, convenient, and economic, and thus are expected to have broad utility to efficiently construct novel compounds for future biological and chemical applications.

  • 34.
    Chorell, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pinkner, Jerome S.
    Department of Molecular Microbiology, Washington University, School of Medicine, St. Louis, Missouri 63110, USA.
    Bengtsson, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Edvinsson, Sofie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Cusumano, Corinne K.
    Rosenbaum, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Johansson, Lennart B-Å
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hultgren, Scott J.
    Department of Molecular Microbiology, Washington University, School of Medicine, St. Louis, Missouri 63110, USA.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Design and synthesis of fluorescently labeled pilicides and curlicides: bioactive tools to study bacterial virulence mechanismsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Pilicides and curlicides block formation of the E. coli virulence factors pili and curli. To facilitate studies of the interaction between these compounds and the pili and curli assembly systems, fluorescent pilicides and curlicides have been synthesized. This was achieved using a strategy where key pilicide and curlicide substituents were replaced by fluorophores having similar physicochemical properties. The resulting fluorescent compounds had improved anti-virulence activities as measured in pili- and curli-dependent biofilm assays. We created fluorescent pilicides and curlicides by introducing both coumarin and 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) fluorophores at two positions on the peptidomimetic pilicide and curlicide scaffold. Fluorescence images of the uropathogenic Escherichia coli (UPEC) strain UTI89 grown in the presence of these compounds shows that the compounds are strongly associated to the bacteria and seem to discriminate between different bacteria in a population.

  • 35. Colak, Burcu
    et al.
    Da Silva, Julio C. S.
    Soares, Thereza A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Departament of Fundamental Chemistry, CCEN, Federal University of Pernambuco, Cidade Universitaria, Brazil.
    Gautrot, Julien E.
    Impact of the Molecular Environment on Thiol-Ene Coupling For Biofunctionalization and Conjugation2016Inngår i: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 27, nr 9, s. 2111-2123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thiol-ene radical coupling is increasingly used for the biofunctionalization of biomaterials and the formation of 3D hydrogels enabling cell encapsulation. Indeed, thiol-ene chemistry presents interesting features that are particularly attractive for platforms requiring specific reactions of peptides or proteins, in particular, in situ, during cell culture or encapsulation. Despite such interest, little is known about the factors impacting thiol-ene chemistry in situ, under biologically relevant conditions. Here we explore some of the molecular parameters controlling photoinitiated thiol-ene couplings with a series of alkenes and thiols, including peptides, in buffered conditions. H-1 NMR and HPLC were used to quantify the efficiency of couplings and the impact of the pH of the buffer, as well as the molecular structure and local microenvironment close to alkenes and thiols to be coupled. Some of these observations are supported by molecular dynamics and quantum mechanics calculations. An important finding of our work is that the plc of thiols (and its variation upon changes in molecular structure) have a striking impact on coupling efficiencies. Similarly, positively charged and aromatic amino acids are found to have some impact on thiol-ene couplings. Hence, our study demonstrates that molecular design should be carefully selected in order to achieve high biofunctionalization levels in biomaterials with peptides or promote the efficient formation of peptide-based hydrogels.

  • 36.
    Dahlgren, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Statistical molecular design, QSAR modeling, and scaffold hopping – Development of type III secretion inhibitors in Gram negative bacteria2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Type III secretion is a virulence system utilized by several clinically important Gram-negative pathogens. Computational methods have been used to develop two classes of type III secretion inhibitors, the salicylidene acylhydrazides and the acetylated salicylanilides. For these classes of compounds, quantitative structure-activity relationship models have been constructed with data from focused libraries obtained by statistical molecular design. The models have been validated and shown to provide useful predictions of untested compounds belonging to these classes. Scaffold hopping of the salicylidene acylhydrazides have resulted in a number of synthetic targets that might mimic the scaffold of the compounds. The synthesis of two libraries of analogs to two of these scaffolds and the biological evaluation of them is presented.

  • 37.
    Dang, Hung The
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chorell, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, USA.
    Uvell, Hanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pinkner, Jerome S.
    Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, USA.
    Hultgren, Scott J.
    Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, USA.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Syntheses and biological evaluation of 2-amino-3-acyl-tetrahydrobenzothiophene derivatives: antibacterial agents with antivirulence activity2014Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 12, nr 12, s. 1942-1956Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Developing new compounds targeting virulence factors (e.g., inhibition of pilus assembly by pilicides) is a promising approach to combating bacterial infection. A high-throughput screening campaign of a library of 17 500 small molecules identified 2-amino-3-acyl-tetrahydrobenzothiophene derivatives (hits 2 and 3) as novel inhibitors of pili-dependent biofilm formation in a uropathogenic Escherichia coli strain UTI89. Based on compounds 2 and 3 as the starting point, we designed and synthesized a series of structurally related analogs and investigated their activity against biofilm formation of E. coli UTI89. Systematic structural modification of the initial hits provided valuable information on their SARs for further optimization. In addition, small structural changes to the parent molecules resulted in low micromolar inhibitors (20-23) of E. coli biofilm development without an effect on bacterial growth. The hit compound 3 and its analog 20 were confirmed to prevent pili formation in a hemagglutination (HA) titer assay and electron microscopy (EM) measurements. These findings suggest that 2-amino-3-acyl-tetrahydrobenzothiophenes may serve as a new class of compounds for further elaboration as antibacterial agents with antivirulence activity.

  • 38. de Araujo Filho, Cesar Augusto
    et al.
    Salmi, Tapio Olavi
    Bernas, Andreas
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kinetic model for homogeneously catalyzed halogenation of glycerol2013Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 52, nr 4, s. 1523-1530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new kinetic model for the halogenation of polyalcohols, e.g. chlorination of glycerol with gaseous HCl in the presence of homogeneous acid catalysts was developed. The model is based on a reaction mechanism, which includes esterification and epoxidation steps followed by halogenation steps. The principle of quasi-steady state was applied to the ester and ionic intermediates appearing in the model and rate equations were derived. Furthermore, some simplified cases of the rate equations were considered, such as immediate water removal from the reaction mixture and analytical solutions for the simplified kinetic models were derived. The model was verified against experimental data obtained from laboratory-scale semibatch reactors. The conclusion is that the model worked very well, predicting correctly the glycerol conversion and the product distribution of α-, β-, α,β- and α,γ-chlorinated products. The kinetic model can be used for design of reactors for homogeneously catalyzed halogenation.

  • 39. Dyson, P J
    et al.
    Laurenczy, G
    Ohlin, C A
    Vallance, J
    Welton, T
    Determination of hydrogen concentration in ionic liquids and the effect (or lack of) on rates of hydrogenation2003Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 19, s. 2418-2419Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solubility of hydrogen and the corresponding Henry coefficients for 11 ionic liquids have been determined in situ at 100 atm H(2) pressure and are much lower than expected; attempts to correlate the solubility of hydrogen in the ionic liquids with the rate of reaction for the hydrogenation of benzene to cyclohexane in these solvents have been made.

  • 40.
    Edo Gimenez, Mar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Energy Engineering, Department of Engineering Sciences & Mathematics, Luleå University of Technology, Luleå, Sweden.
    Gao, Qiuju
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Persson, Per-Erik
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Fate of metals and emissions of organic pollutants from torrefaction of waste wood, MSW, and RDF2017Inngår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 68, s. 646-652Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Torrefaction of municipal solid waste (MSW), refuse-derived fuel (RDF), and demolition and construction wood (DC) was performed at 220°C and a residence time of 90 min in a bench-scale reactor. The levels of toxic polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) contained in emission from the torrefaction process were evaluated. In addition, main ash-forming elements and trace metals in the raw feedstock and char were determined. The use of MSW in fuel blends with DC resulted in lower PCDD and PCDF emissions after torrefaction, compared with the RDF blends. The migration of chlorine from the feedstock to the gas phase reduces the chlorine content of the char which may reduce the risk of alkali chloride-corrosion in char combustion. However, trace metals catalytically active in the formation of PCDD and PCDF remain in the char, thereby may promote PCDD and PCDF formation during subsequent char combustion for energy recovery; this formation is less extensive than when the feedstock is used.

  • 41.
    Edo Giménez, Mar
    et al.
    Umeå universitet.
    Ortuño,, N
    Conesa, J.A
    Persson, P-E
    Jansson, S
    Emissions from co-combustion of demolition and construction wood and household waste fuel blendsManuskript (preprint) (Annet vitenskapelig)
  • 42.
    Edvinsson, Sofie
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Johansson, Susanne
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    An efficient procedure for the synthesis of formylacetic esters2012Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 53, nr 50, s. 6819-6821Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient synthesis of formylacetic esters via ozonolysis of trans-beta-hydromuconic esters followed by a solid-supported triphenylphosphine reduction has been developed. In addition, an extension toward formylacetic amides and a one-pot preparation of more stable intermediates which can be used for further transformations are also described.

  • 43.
    Emtenäs, Hans
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Synthesis and biological evaluation of Bicyclic β-Lactams and 2-Pyridinones: Pilicides Targeting Pilus Biogenesis in Pathogenic Bacteria2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    New methods have been developed for the synthesis of bicyclic β-lactams and 2-pyridinones by combining acyl Meldrum’s acids and Δ2-thiazolines. The 2-pyridinones were synthesised both in solution using conventional heating or microwave assisted heating as well as by solid supported chemistry.

    The compounds (pilicides) were designed to interfere with the assembly of pili in uropathogenic E. coli by inhibiting the periplasmic chaperones. The affinity of the pilicides to the chaperones was investigated with surface plasmon resonance technique (Biacore) and with relaxation-edited 1H NMR spectroscopy experiments. Finally, the pilicides were investigated for their ability to inhibit pili formation in uropathogenic E. coli in a hemagglutination assay, where members of the 2-pyridinone family proved to be able to cause depiliation.

  • 44.
    Emtenäs, Hans
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Soto, Gabe
    Hultgren, Scott J.
    Marshall, Garland R.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Stereoselective Synthesis of Optically Active β-Lactams, Potential Inhibitors of Pilus Assembly in Pathogenic Bacteria2000Inngår i: Organic Letters, Vol. 2, s. 2065-2067Artikkel i tidsskrift (Fagfellevurdert)
  • 45.
    Engdahl, Cecilia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Knutsson, Sofie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ekström, Fredrik
    Linusson, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Discovery of selective inhibitors targeting acetylcholinesterase 1 from disease-transmitting mosquitoes2016Inngår i: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 59, nr 20, s. 9409-9421Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Vector control of disease-transmitting mosquitoes is increasingly important due to the re-emergence and spread of infections such as malaria and dengue. We have conducted a high throughput screen (HTS) of 17,500 compounds for inhibition of the essential AChE1 enzymes from the mosquitoes Anopheles gambiae and Aedes aegypti. In a differential HTS analysis including the human AChE, several structurally diverse, potent, and selective noncovalent AChE1 inhibitors were discovered. For example, a phenoxyacetamide-based inhibitor was identified with a 100-fold selectivity for the mosquito over the human enzyme. The compound also inhibited a resistance conferring mutant of AChE1. Structure-selectivity relationships could be proposed based on the enzymes' 3D structures; the hits' selectivity profiles appear to be linked to differences in two loops that affect the structure of the entire active site. Noncovalent inhibitors of AChE1, such as the ones presented here, provide valuable starting points toward insecticides and are complementary to existing and new covalent inhibitors.

  • 46.
    Eriksson, Lennart
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    A strategy for ranking environmentally occuring chemicals1991Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A systematic methodology for quantitative structure-activity relationship (QSAR) development in environmental toxicology is provided. The methodology is summarized in a strategy with six sequential steps.

    The strategy rests on two cornerstones, namely (1) the use of statistical design to select a series of representative compounds (the so-called training set) on which to base a QSAR, and (2) the multivariate modelling of the relationship between physicochemical and biological properties of the training set compounds.

    The first step of the strategy is the division of chemicals into classes of structurally similar compounds. Briefly, steps 2 to 6 are: (2) physico-chemical and structural characterization of the compounds in a class, (3) selection of a training set of representative compounds, (4) biological testing of the selected training set, (5) QSAR model development, and (6) experimental validation of the QSAR and predictions for non-tested compounds.

    The thesis summarizes the results obtained from the application of the strategy to the class of halogenated aliphatic compounds. Biological measurements were made in four biological test systems, reflecting acute toxicity, mutagenicity, relative cytotoxicity and genotoxicity. QSARs were developed relating each biological endpoint to the structural descriptors of the compounds. Multivariate PLS modelling was used in the data analysis. The developed QSARs were used for predicting the biological activity pattern of the non-tested compounds in the class. These predictions may be used as a starting point for a priority ranking for further biological testing of these compounds.

    The strategy has not been developed solely for establishing QSARs for the halogenated aliphatics class. On the contrary, this work is intended to demonstrate a generally applicable QSAR methodology.

  • 47. Forsum, Oskar
    et al.
    Näsholm, Torgny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Transformation of Plants with D-Amino Acid Resistance Selectable Markers2009Inngår i: D-Amino Acids: Practical Methods and Protocols, Volume 4: Enzymes Involved in the Metabolism of D-Amino Acids / [ed] Ryuichi Konno, Hans Brückner, Antimo D'Aniello, George H. Fisher, Noriko Fujii and Hiroshi Homma, Hauppauge: Nova Science Publishers, Inc., 2009, s. 73-79Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 48.
    Gabrielsson, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Multivariate methods in tablet formulation2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the application of multivariate methods in a novel approach to the formulation of tablets for direct compression. It begins with a brief historical review, followed by a basic introduction to key aspects of tablet formulation and multivariate data analysis. The bulk of the thesis is concerned with the novel approach, in which excipients were characterised in terms of multiple physical or (in most cases) spectral variables. By applying Principal Component Analysis (PCA) the descriptive variables are summarized into a few latent variables, usually termed scores or principal properties (PP’s). In this way the number of descriptive variables is dramatically reduced and the excipients are described by orthogonal continuous variables. This means that the PP’s can be used as ordinary variables in a statistical experimental design. The combination of latent variables and experimental design is termed multivariate design or experimental design in PP’s. Using multivariate design many excipients can be included in screening experiments with relatively few experiments.

    The outcome of experiments designed to evaluate the effects of differences in excipient composition of formulations for direct compression is, of course, tablets with various properties. Once these properties, e.g. disintegration time and tensile strength, have been determined with standardised tests, quantitative relationships between descriptive variables and tablet properties can be established using Partial Least Squares Projections to Latent Structures (PLS) analysis. The obtained models can then be used for different purposes, depending on the objective of the research, such as evaluating the influence of the constituents of the formulation or optimisation of a certain tablet property.

    Several examples of applications of the described methods are presented. Except in the first study, in which the feasibility of this approach was first tested, the disintegration time of the tablets has been studied more carefully than other responses. Additional experiments have been performed in order to obtain a specific disintegration time. Studies of mixtures of excipients with the same primary function have also been performed to obtain certain PP’s. Such mixture experiments also provide a straightforward approach to additional experiments where an interesting area of the PP space can be studied in more detail. The robustness of a formulation with respect to normal batch-to-batch variability has also been studied.

    The presented approach to tablet formulation offers several interesting alternatives, for both planning and evaluating experiments.

  • 49.
    Gandla, Madhavi Latha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Derba-Maceluch, Marta
    Liu, Xiaokun
    Gerber, Lorenz
    Master, Emma R.
    Mellerowicz, Ewa J.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Expression of a fungal glucuronoyl esterase in Populus: Effects on wood properties and saccharification efficiency2015Inngår i: Phytochemistry, ISSN 0031-9422, E-ISSN 1873-3700, Vol. 112, s. 210-220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The secondary walls of angiosperms contain large amounts of glucuronoxylan that is thought to be covalently linked to lignin via ester bonds between 4-O-methyl-alpha-D-glucuronic acid (4-O-Me-GlcA) moieties in glucuronoxylan and alcohol groups in lignin. This linkage is proposed to be hydrolysed by glucuronoyl esterases (GCEs) secreted by wood-degrading fungi. We report effects of overexpression of a GCE from the white-rot basidiomycete Phanerochaete carnosa, PcGCE, in hybrid aspen (Populus tremula L. x tremuloides Michx.) on the wood composition and the saccharification efficiency. The recombinant enzyme, which was targeted to the plant cell wall using the signal peptide from hybrid aspen cellulase PttCel9B3, was constitutively expressed resulting in the appearance of GCE activity in protein extracts from developing wood. Diffuse reflectance FT-IR spectroscopy and pyrolysis-GC/MS analyses showed significant alternation in wood chemistry of transgenic plants including an increase in lignin content and S/G ratio, and a decrease in carbohydrate content Sequential wood extractions confirmed a massive (+43%) increase of Klason lignin, which was accompanied by a ca. 5% decrease in cellulose, and ca. 20% decrease in wood extractives. Analysis of the monosaccharide composition using methanolysis showed a reduction of 4-O-Me-GlcA content without a change in Xyl contents in transgenic lines, suggesting that the covalent links between 4-O-Me-GlcA moieties and lignin protect these moieties from degradation. Enzymatic saccharification without pretreatment resulted in significant decreases of the yields of Gal, Glc, Xyl and Man in transgenic lines, consistent with their increased recalcitrance caused by the increased lignin content In contrast, the enzymatic saccharification after acid pretreatment resulted in Glc yields similar to wild-type despite of their lower cellulose content. These data indicate that whereas PcGCE expression in hybrid aspen increases lignin deposition, the inhibitory effects of lignin are efficiently removed during acid pretreatment, and the extent of wood cellulose conversion during hydrolysis after acid pretreatment is improved in the transgenic lines possible due to reduced cell wall cross-links between cell wall biopolymers by PcGCE. 

  • 50.
    Gao, Qiuju
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Dioxins and dioxin-like compounds in thermochemical conversion of biomass: formation, distribution and fingerprints2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In the transition to a sustainable energy supply there is an increasing need to use biomass for replacement of fossil fuel. A key challenge is to utilize biomass conversion technologies in an environmentally sound manner. Important aspects are to minimize potential formation of persistent organic pollutants (POPs) such as dioxins and dioxin-like compounds.

    This thesis involves studies of formation characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) in microwave-assisted pyrolysis (MAP) and torrefaction using biomass as feedstock. The research focuses are on their levels, distributions, fingerprints (homologue profiles and isomer patterns) and the underlying formation pathways. The study also included efforts to optimize methods for extracting chlorinated aromatic compounds from thermally treated biomass. The overall objective was to contribute better understanding on the formation of dioxins and dioxin-like compounds in low temperature thermal processes.

    The main findings include the following:

    • Pressurized liquid extraction (PLE) is applicable for simultaneous extraction of PCDDs, PCDFs, PCNs, polychlorinated phenols and benzenes from thermally treated wood. The choice of solvent for PLE is critical, and the extraction efficiency depends on the degrees of biomass carbonization.
    • In MAP experiments PCDDs, PCDFs and PCNs were predominantly found in pyrolysis oils, while in torrefaction experiments they were mainly retained in solid chars with minor fractions in volatiles. In both cases, highly chlorinated congeners with low volatility tended to retain on particles whereas the less chlorinated congeners tended to volatize into the gas phase.
    • Isomer patterns of PCDDs, PCDFs and PCNs generated in MAP were more selective than those reported in combustion processes. The presence of isomers with low thermodynamic stability suggests that the pathway of POPs formation in MAP may be governed not only by thermodynamic stabilities but also by kinetic factors.
    • Formation of PCDDs, PCDFs and PCNs depends not only on the chlorine contents in biomass but also the presence of metal catalysts and organic/metal-based preservatives.

    Overall, the results provide information on the formation characteristics of PCDDs, PCDFs and PCNs in MAP and torrefaction. The obtained knowledge is useful regarding management and utilization of thermally treated biomass with minimum environmental impact.

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