• Investigation of tetrasubstituted heterocycles reveals hydantoins as a promising scaffold for development of novel antimicrobials with membranolytic properties 

      Langer, Manuel K; Rahman, Ataur; Dey, Hymonti; Anderssen, Trude; Blencke, Hans-Matti; Haug, Tor; Stensvåg, Klara; Strøm, Morten B.; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-24)
      Mimics of antimicrobial peptides (AMPs) have been proposed as a promising class of antimicrobial agents. We report the analysis of five tetrasubstituted, cationic, amphipathic heterocycles as potential AMP mimics. The analysis showed that the heterocyclic scaffold had a strong influence on the haemolytic activity of the compounds, and the hydantoin scaffold was identified as a promising template for ...
    • Iridium-PHOX-mediated alkene hydrogenation: Isomerisation influences the stereochemical outcome 

      Hopmann, Kathrin Helen; Frediani, Luca; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-05-27)
      Recent experimental studies of iridium-phosphinooxazoline-mediated alkene hydrogenation indicated two dihydride species as resting states, with the minor isomer assumed to give rise to the major product enantiomer [Gruber and Pfaltz, Angew. Chem. Int. Ed. 2014, 53, 1896]. B3LYP-D2 calculations confirm the two dihydride intermediates as resting states but show that these species do not give rise to ...
    • Iron‐Catalyzed Carbenoid Transfer Reactions of Vinyl Sulfoxonium Ylides: An Experimental and Computational Study 

      Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-15)
      A method for the generation of unprecedented vinyl carbenoids from sulfoxonium ylides has been developed and applied in the synthesis of a diverse array of heterocycles such as indolizines, pyrroles, 3‐pyrrolin‐2‐ones, and furans. The reactions proceed by FeBr<sub>2</sub> catalysis under mild reaction conditions with a broad substrate scope. A reaction pathway involving iron carbenoids is proposed ...
    • Kinase chemodiversity from the Arctic: the breitfussins 

      Østnes Hansen, Kine; Andersen, Jeanette hammer; Bayer, Annette; Pandey, Sunil Kumar; Lorentzen, Marianne; Jørgensen, Kåre Bredeli; Sydnes, Magne Olav; Guttormsen, Yngve; Baumann, Matthias; Koch, Uwe; Klebl, Bert; Eickhoff, Jan; Haug, Bengt Erik; Isaksson, Johan; Hansen, Espen (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-24)
      In this work, we demonstrate that the indole-oxazole-pyrrole framework of the breitfussin family of natural products is a promising scaffold for kinase inhibition. Six new halogenated natural products, breitfussin C–H (3 – 8) were isolated and characterized from the Arctic, marine hydrozoan Thuiaria breitfussi. The structures of two of the new natural products were also confirmed by total synthesis. ...
    • Lipids as Versatile Solvents for Chemical Synthesis 

      Gevorgyan, Ashot; Hopmann, Kathrin Helen; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-23)
      Development of safe, renewable, cheap and versatile solvents is a longstanding challenge in chemistry. We show here that vegetable oils and related systems can become prominent solvents for organic synthesis. Suzuki–Miyaura, Hiyama, Stille, Sonogashira and Heck cross-couplings proceed with quantitative yields in a range of vegetable oils, fish oil, butter and waxes used as solvents. Appropriate ...
    • The Marine Natural Product Mimic MHP88 Shows Anticancer Activity and has the Potential to Cause Immunogenic Cell Death 

      von Hofsten, Susannah; Norvoll Magnussen, Synnøve; Ausbacher, Dominik; Paulsen, Marianne Hagensen; Bayer, Annette; Strøm, Morten B.; Berge, Gerd (Conference object; Konferansebidrag, 2020-03)
      The marine natural product mimic MHP 88 is a novel synthetic molecule based on unique structures found in molecules from an arctic marine bryozoan. Initial studies showed that MHP88 kills cancer cells efficiently, but is not hemolytic. In this study, we look closer at the mode of death induced by MHP88 in oral cancer (HSC-3) and lymphoma (Ramos) cell lines. Immunogenic cell death (ICD) is a mode of ...
    • The marine natural product mimic MPM-1 is cytolytic and induces DAMP release from human cancer cell lines 

      von Hofsten, Susannah; Paulsen, Marianne Hagensen; Magnussen, Synnøve; Ausbacher, Dominik; Kranz, Mathias; Bayer, Annette; Strøm, Morten Bøhmer; Berge, Gerd (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-16)
      Bioprospecting contributes to the discovery of new molecules with anticancer properties. Compounds with cytolytic activity and the ability to induce immunogenic cell death can be administered as intratumoral injections with the aim to activate anti-tumor immune responses by causing the release of tumor antigens as well as damage-associated molecular patterns (DAMPs) from dying cancer cells. In ...
    • Mechanistic Insights into Copper-Catalyzed Carboxylations 

      Obst, Marc; Gevorgyan, Ashot; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-02)
      The copper-NHC-catalyzed carboxylation of organoboranes with CO<sub>2</sub> was investigated using computational and experimental methods. The DFT and DLPNO-CCSD(T) results indicate that nonbenzylic substrates are converted via an inner-sphere carboxylation of an organocopper intermediate, whereas benzylic substrates may simultaneously proceed along both inner- and outer-sphere CO<sub>2</sub> insertion ...
    • Metallo-β-lactamase inhibitors by bioisosteric replacement: preparation, activity and binding 

      Skagseth, Susann; Akhter, Sundus; Paulsen, Marianne H; Muhammad, Zeeshan; Samuelsen, Ørjan; Leiros, Hanna-Kirsti S.; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-14)
      Bacterial resistance is compromising the use of β-lactam antibiotics including carbapenems. The main resistance mechanism against β-lactams is hydrolysis of the β-lactam ring mediated by serine- or metallo-β-lactamases (MBLs). Although several inhibitors of MBLs have been reported, none has been developed into a clinically useful inhibitor. Mercaptocarboxylic acids are among the most prominent ...
    • NMR Backbone Assignment of VIM-2 and Identification of the Active Enantiomer of a Potential Inhibitor 

      Wieske, Lianne H. E.; Bogaerts, Jonathan; Leding, Albin A. M.; Wilcox, Scott; Rasmussen, Anna Andersson; Leszczak, Kinga; Turunen, Lotta; Herrebout, Wouter A.; Hubert, Madlen; Bayer, Annette; Erdelyi, Mate (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-28)
      Carbapenem resistance caused by metallo-β-lactamases is a serious global challenge that, if not tackled efficiently, is expected to lead to millions of deaths in the coming decades. Verona-integron encoded metallo-β-lactamase 2 (VIM-2) is a bacterial enzyme that has been reported from multidrug-resistant nosocomial isolates of Pseudomonas aeruginosa and other Gram-negative pathogens. As it hydrolyzes ...
    • Palladium(0)-Catalyzed Cross-Couplings of 2-Bromophosphinine 

      Kostenko, Nataliya; Eriksson, Cecilia; Engqvist, Magnus; Villa Gonzalez, Susana; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05-21)
      A new Negishi-type cross-coupling of 2-bromophosphinine has been developed. The new method expands the scope of palladium-catalyzed couplings to monobromophosphinines, which have been considered as poor substrates so far. Moreover, aryl-, alkenyl-, and alkynylzinc bromides were found to be effective coupling partners.
    • Polymyxin B stabilized DNA micelles for sustained antibacterial and antibiofilm activity against P. aeruginosa 

      Antunes de Sousa, Alexandra Sofia; Borøy, Vegard; Bæverud, Agnethe Hansen; Julin, Kjersti; Bayer, Annette; Strøm, Morten B.; Johannessen, Mona Susan; Skalko Basnet, Natasa; Obuobi, Sybil Akua Okyerewa (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-21)
      Nucleic acid-based materials showcase an increasing potential for antimicrobial drug delivery. Although numerous reports on drug-loaded DNA nanoparticles outline their pivotal antibacterial activities, their potential as drug delivery systems against bacterial biofilms awaits further studies. Among different oligonucleotide structures, micellar nanocarriers derived from amphiphilic DNA strands ...
    • Renewable Solvents for Palladium-Catalyzed Carbonylation Reactions 

      Ismael, Aya; Gevorgyan, Ashot; Skrydstrup, Troels; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-04)
      Solvents constitute the largest component for many chemical processes and substitution of nonrenewable solvents is a longstanding goal for green chemistry. Here, we show that Pd-catalyzed carbonylative couplings, such as carbonylative cross-couplings, aminocarbonylations, and alkoxycarbonylations, can be successfully realized using renewable solvents. The present research covers not only well-established ...
    • Rhodium-Catalyzed Hydrocarboxylation: Mechanistic Analysis Reveals Unusual Transition State for Carbon–Carbon Bond Formation 

      Pavlovic, Ljiljana; Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-12)
      The mechanism of rhodium-COD-catalyzed hydrocarboxylation of styrene derivatives and α,β-unsaturated carbonyl compounds with CO<sub>2</sub> has been investigated using density functional theory (PBE-D2/IEFPCM). The calculations support a catalytic cycle as originally proposed by Mikami and co-workers including β-hydride elimination, insertion of the unsaturated substrate into a rhodium–hydride bond, ...
    • Rhodium-Catalyzed Synthesis of Sulfur Ylides via in Situ Generated Iodonium Ylides 

      Vaitla, Janakiram; Hopmann, Kathrin H.; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-22)
      A convenient strategy for the synthesis of sulfur ylides via rhodium-catalyzed coupling of in situ generated iodonium ylides with sulfides or sulfoxides has been developed. A wide range of sulfur ylides were obtained in moderate to good yields from inexpensive sulfur compounds and active methylene compounds with a short reaction time (MW, 5–10 min) or 12–16 h at rt. Furthermore, these sulfoxonium ...
    • Screening and Design of Inhibitor Scaffolds for the Antibiotic Resistance Oxacillinase-48 (OXA-48) through Surface Plasmon Resonance Screening 

      Lund, Bjarte Aarmo; Christopeit, Tony; Guttormsen, Yngve; Bayer, Annette; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)
      The spread of antibiotic resistant bacteria is a global threat that shakes the foundations of modern healthcare. β-Lactamases are enzymes that confer resistance to β-lactam antibiotics in bacteria, and there is a critical need for new inhibitors of these enzymes for combination therapy together with an antibiotic. With this in mind, we have screened a library of 490 fragments to identify starting ...
    • Structural insights into TMB-1 and the role of residues 119 and 228 in substrate and inhibitor binding 

      Skagseth, Susann; Christopeit, Tony; Akhter, Sundus; Bayer, Annette; Samuelsen, Ørjan; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-30)
      Metallo-β-lactamases (MBLs) threaten the effectiveness of β-lactam antibiotics, including carbapenems, and are a concern for global public health. β-Lactam/β-lactamase inhibitor combinations active against class A and class D carbapenemases are used, but no clinically useful MBL inhibitor is currently available. Tripoli metallo-β-lactamase-1 (TMB-1) and TMB-2 are members of MBL subclass B1a, where ...
    • Structural studies of triazole inhibitors with promising inhibitor effects against antibiotic resistance metallo-β-lactamases 

      Muhammad, Zeeshan; Skagseth, Susann; Boomgaren, Marc; Akhter, Sundus; Frøhlich, Christopher; Ismael, Aya; Christopeit, Tony; Bayer, Annette; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-18)
      Metallo-β-lactamases (MBLs) are an emerging cause of bacterial antibiotic resistance by hydrolysing all classes of β-lactams except monobactams, and the MBLs are not inhibited by clinically available serine-β-lactamase inhibitors. Two of the most commonly encountered MBLs in clinical isolates worldwide – the New Delhi metallo-β-lactamase (NDM-1) and the Verona integron-encoded metallo-β-lactamase ...
    • Sulfoxonium Ylide Derived Metal Carbenoids in Organic Synthesis 

      Vaitla, Janakiram; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-12)
      As pioneered by Corey and Chaykovsky, sulfoxonium ylides have had widespread application in organic synthesis for more than a half century. In most of the reactions, sulfoxonium ylides were used to react with electrophiles. Under suitable reaction conditions these ylides can generate metal carbenoids and react with nucleophiles. By combining the typical reactivity of sulfoxonium ylides with ...
    • Synthesis of Indoles and Pyrroles Utilizing Iridium Carbenes Generated from Sulfoxonium Ylides 

      Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-20)
      Metal carbenes can undergo a myriad of synthetic transformations. Sulfur ylides are potential safe precursors of metal carbenes. Herein, we report cascade reactions that involve carbenoids derived from sulfoxonium ylides for the efficient and regioselective synthesis of indoles and pyrroles. The tandem action of iridium and Brønsted acid catalysts enables rapid assembly of the heterocycles from ...