Analytical & Biological Chemistry Research Facility - Journal Articles

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    Synthesis and evaluation of aromatic BDSF bioisosteres on biofilm formation and colistin sensitivity in pathogenic bacteria
    (Elsevier, 2023-09-23) Gómez, Andromeda-Celeste; Horgan, Conor; Yero, Daniel; Bravo, Marc; Daura, Xavier; O'Driscoll, Michelle; Gibert, Isidre; O'Sullivan, Timothy P.; Irish Research Council; Ministerio de Ciencia e Innovación; Agència de Gestió d'Ajuts Universitaris i de Recerca
    The diffusible signal factor family (DSF) of molecules play an important role in regulating intercellular communication, or quorum sensing, in several disease-causing bacteria. These messenger molecules, which are comprised of cis-unsaturated fatty acids, are involved in the regulation of biofilm formation, antibiotic tolerance, virulence and the control of bacterial resistance. We have previously demonstrated how olefinic N-acyl sulfonamide bioisosteric analogues of diffusible signal factor can reduce biofilm formation or enhance antibiotic sensitivity in a number of bacterial strains. This work describes the design and synthesis of a second generation of aromatic N-acyl sulfonamide bioisosteres. The impact of these compounds on biofilm production in Acinetobacter baumannii, Escherichia coli, Burkholderia multivorans, Burkholderia cepacia, Burkholderia cenocepacia, Pseudomonas aeruginosa and Stenotrophomonas maltophilia is evaluated, in addition to their effects on antibiotic tolerance. The ability of these molecules to increase survival rates on co-administration with colistin is also investigated using the Galleria infection model.
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    Organocatalytic asymmetric peroxidation of g,d-unsaturated ß-keto esters - A novel route to chiral cycloperoxides
    (2023-05-24) Hennessy, Mary C.; Hirenkumar, Gandhi; O'Sullivan, Timothy P.; Irish Research Council; Science Foundation Ireland
    A methodology for the asymmetric peroxidation of g,d-unsaturated ß-keto esters is presented. Using a cinchona-derived organocatalyst, the target d-peroxy-ß-keto esters were obtained in high enantiomeric ratios of up to 95:5. Additionally, these d-peroxy esters can be readily reduced to chiral d-hydroxy-ß-keto esters without impacting the ß-keto ester functionality. Importantly, this chemistry opens up a concise route to chiral 1,2-dioxolanes, a common motif in many bioactive natural products, via a novel P2O5-mediated cyclisation of the corresponding d-peroxy-ß-hydroxy esters.
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    Major structure-activity relationships of resolvins, protectins, maresins and their analogues
    (Future Science Ltd, 2022-11-30) Daly, Kevin; O'Sullivan, Killian; O'Sullivan, Timothy P.
    Resolvins, protectins and maresins are a series of polyunsaturated fatty acid-derived molecules which play important roles in the resolution of inflammation. They are termed specialized proresolving mediators and facilitate a return to homeostasis following an inflammatory response. These molecules are currently the focus of intensive investigation, primarily for their ability to suppress inflammation in chronic disease states. Researchers have employed different synthetic approaches to assess whether various structural modifications of these compounds could provide access to future therapeutics. This review summarizes the modifications made thus far and focuses on the key structure-activity relationships which have been uncovered for resolvins, protectins, maresins and their analogues.
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    Pharmaceutical salts of piroxicam and meloxicam with organic counterions
    (ACS Publications, 2022-10-21) Huang, Shan; Venables, Dean S.; Lawrence, Simon E.; Science Foundation Ireland
    Piroxicam (PRM) and meloxicam (MEL) are two nonsteroidal anti-inflammatory drugs, belonging to the Biopharmaceutics Classification System Class II drugs. In this study, six novel pharmaceutical salts of PRM and MEL with three basic organic counterions, that is, 4-aminopyridine (4AP), 4-dimethylaminopyridine (4DMP), and piperazine (PPZ), were prepared by both slurrying and slow evaporation. These salts were characterized by single-crystal and powder X-ray diffraction, thermal analysis, and Fourier transform infrared spectroscopy. All six salts, especially MEL-4DMP and MEL-4AP, showed a significantly improved apparent solubility and dissolution rate in sodium phosphate solution compared with the pure APIs. Notably, PRM-4AP and PRM-4DMP salts exhibited enhanced fluorescence, and the PRMPPZ salt showed weaker fluorescence compared with that of pure PRM due to different luminescence mechanisms.
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    Synthesis and reactivity of dihalofuranones
    (Bentham Science Publishers, 2022-08-01) Lyons, Thérèse A.; Gahan, Cormac G. M.; O'Sullivan, Timothy P.; Science Foundation Ireland
    Halogenated furanones have been found to act as potent quorum sensing inhibitors in several bacterial species. It is believed that dihalofuranones covalently bind to the LuxS enzyme, which is necessary for autoinducer-2 synthesis. In addition to their antimicrobial activity, halogen-ated furanones also possess anti-cancer, antioxidant, and depigmentation properties. However, traditional routes to these compounds are low-yielding and capricious. The aim of this study was to investigate higher-yielding preparations of gem-dihalofuranones and compare their reactivity using Suzuki chemistry. Ramirez dibromoolefination of maleic anhydride was optimised using a variety of conditions. A similar route was investigated for the preparation of bromofluorofuranones and dichlorofuranones. The conversion of a dichlorofuranone to the corresponding iodofuranone derivatives using microwave-assisted Finkelstein chemistry was also studied. Lastly, the reactivity of the different dihalofuranones was compared by Pd-mediated coupling with phenylboronic acid. A higher-yielding, concise synthesis of dibromofuranones was developed using a modified Ramirez reaction. Additionally, a telescoped preparation of dichlorofuranone was higher yielding than previous approaches. Bromine-and iodine-substituted dihalofuranones proved more reactive than their chlorine-substituted analogues. Higher yielding routes to bromine-, fluorine-, chlorine-and iodine-containing dihalofuranones were successfully developed. Suzuki couplings of gem-dihalofuranones were found to proceed with high stereoselectivity.