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Search for "resistance" in Full Text gives 316 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Synthesis of polydicyclopentadiene using the Cp2TiCl2/Et2AlCl catalytic system and thin-layer oxidation of the polymer in air

  • Zhargolma B. Bazarova,
  • Ludmila S. Soroka,
  • Alex A. Lyapkov,
  • Мekhman S. Yusubov and
  • Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

Graphical Abstract
  • process with a digital thermometer, consisting of a platinum thin film resistance thermometer placed on a ceramic substrate and placed in a stainless steel thin-wall case. The catalyst for cationic DCPD polymerization is a complex that is formed during the interaction of Cp2TiCl2 with AlEt2Cl. The
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Published 20 Mar 2019

Design and synthesis of multivalent α-1,2-trimannose-linked bioerodible microparticles for applications in immune response studies of Leishmania major infection

  • Chelsea L. Rintelmann,
  • Tara Grinnage-Pulley,
  • Kathleen Ross,
  • Daniel E. K. Kabotso,
  • Angela Toepp,
  • Anne Cowell,
  • Christine Petersen,
  • Balaji Narasimhan and
  • Nicola Pohl

Beilstein J. Org. Chem. 2019, 15, 623–632, doi:10.3762/bjoc.15.58

Graphical Abstract
  • are no approved anti-leishmanial vaccines and the current therapeutics are toxic, expensive and prone to induce resistance, such as, amphotericin B (AmB), paromomycin and antimony-based chemotherapeutics [7][8][9]. With growing resistance to antileishmanial drugs and poor patient compliance, the
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Published 11 Mar 2019

Low-budget 3D-printed equipment for continuous flow reactions

  • Jochen M. Neumaier,
  • Amiera Madani,
  • Thomas Klein and
  • Thomas Ziegler

Beilstein J. Org. Chem. 2019, 15, 558–566, doi:10.3762/bjoc.15.50

Graphical Abstract
  • shows a good resistance towards common solvents. A disadvantage of FDM is the relatively low resolution [20]. Oligosaccharides, especially as glycoconjugates, play a crucial biological role in nature, e.g., for signal transduction in cell–cell recognition, infection processes, and immunology [21][22
  • systems is the low chemical resistance of the used printing materials towards most organic solvents [11]. For the development and construction of our flow reactor we had to print and design numerous devices in order to find the most suitable parameters. All reactors were printed with a filament flow of
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Published 26 Feb 2019

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

  • Patrycja Żak and
  • Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

Graphical Abstract
  • the main chain (Scheme 18) [24]. The products were polymers characterized by Mn in the range from 9100 to 18300 Da and Mw in the range from 13600 to 46100 Da. Thermogravimetric analyses indicate a high level of thermal resistance of the obtained systems, reaching the temperature values over 550 °C
  • can significantly improve such properties of the polymer as thermal and oxidative resistance, surface properties, improvement of mechanical properties as well as reduced flammability, heat release and viscosity during processing [29]. Synthesis, properties and applications of POSS-containing materials
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Published 04 Feb 2019

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

  • Tegene T. Tole,
  • Johan H. L. Jordaan and
  • Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

Graphical Abstract
  • Å) bond length in 8 is longer and the Cα–O (1.417 Å) and Cα–C2 (1.532 Å) bonds are shorter than the corresponding bonds in 6. In order to overcome the combined effect of the resistance that resulted from the steric crowdedness and the inductive electron-donation by the 3-Me group and open the strong
  • Ru–N chelation, it needs relatively high energy. In 8 the methyl group is in exactly the opposite orientation to the two α-phenyl groups. Therefore, the steric crowdedness that is observed in 6 that will lead to steric resistance to open the Ru–N chelation does not exist. Thus 8 is more susceptible
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Published 22 Jan 2019

Adhesion, forces and the stability of interfaces

  • Robin Guttmann,
  • Johannes Hoja,
  • Christoph Lechner,
  • Reinhard J. Maurer and
  • Alexander F. Sax

Beilstein J. Org. Chem. 2019, 15, 106–129, doi:10.3762/bjoc.15.12

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  • distortions are called rigid or stiff, the resistance of electron distributions against distortion is called its hardness. By freezing the geometries of the interacting subsystems the interaction energy is calculated as if the interacting subsystems were ideally rigid. The intermolecular contributions to the
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Published 11 Jan 2019

Lectins of Mycobacterium tuberculosis – rarely studied proteins

  • Katharina Kolbe,
  • Sri Kumar Veleti,
  • Norbert Reiling and
  • Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2019, 15, 1–15, doi:10.3762/bjoc.15.1

Graphical Abstract
  • connected to colonization of the kidney [64][65]. Inhibition of carbohydrate–lectin interactions by antiadhesive drugs is an emerging anti-infective therapeutic approach, particularly in light of increasing rates of bacterial resistance to traditional antibiotics. α-D-Mannosides containing aromatic aglycons
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Published 02 Jan 2019

Repurposing the anticancer drug cisplatin with the aim of developing novel Pseudomonas aeruginosa infection control agents

  • Mingjun Yuan,
  • Song Lin Chua,
  • Yang Liu,
  • Daniela I. Drautz-Moses,
  • Joey Kuok Hoong Yam,
  • Thet Tun Aung,
  • Roger W. Beuerman,
  • May Margarette Santillan Salido,
  • Stephan C. Schuster,
  • Choon-Hong Tan,
  • Michael Givskov,
  • Liang Yang and
  • Thomas E. Nielsen

Beilstein J. Org. Chem. 2018, 14, 3059–3069, doi:10.3762/bjoc.14.284

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  • 637371 Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 København N, Denmark 10.3762/bjoc.14.284 Abstract Antibiotic resistance threatens effective treatment of microbial infections globally. This situation has spurred the hunt for new antimicrobial
  • infections. Keywords: biofilm; cisplatin; Pseudomonas aeruginosa; resistance; type III secretion; Introduction Pseudomonas aeruginosa is a leading nosocomial pathogen which causes, among others, corneal, chronic otitis media, urinary tract (UTI) and respiratory tract infections [1]. P. aeruginosa is also
  • further validate the impact of cisplatin on DNA replication, we compared the cisplatin sensitivity of the P. aeruginosa wild-type PAO1 strain and its DNA recombination-deficient recA mutant and found that the rec recombination pathway was essential for the cisplatin resistance in P. aeruginosa (Figure 4
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Published 14 Dec 2018

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum

  • Jan Rinkel,
  • Alexander Babczyk,
  • Tao Wang,
  • Marc Stadler and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277

Graphical Abstract
  • germination and to cause necrotic lesions in the plant tissue. In other cases, fungal volatiles can have beneficial effects and may even be involved in the induction of systemic resistance in plants, as can be assumed for 6-pentyl-2H-pyran-2-one (5) that is produced by many fungi from the genus Trichoderma
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Published 04 Dec 2018

Protein–protein interactions in bacteria: a promising and challenging avenue towards the discovery of new antibiotics

  • Laura Carro

Beilstein J. Org. Chem. 2018, 14, 2881–2896, doi:10.3762/bjoc.14.267

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  • Laura Carro School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK 10.3762/bjoc.14.267 Abstract Antibiotics are potent pharmacological weapons against bacterial infections; however, the growing antibiotic resistance of microorganisms is compromising the efficacy
  • of the currently available pharmacotherapies. Even though antimicrobial resistance is not a new problem, antibiotic development has failed to match the growth of resistant pathogens and hence, it is highly critical to discover new anti-infective drugs with novel mechanisms of action which will help
  • represent an alternative lead discovery strategy to obtain new anti-infective molecules. Keywords: new antibiotics; protein–protein interactions; resistance; Introduction Bacterial infections are not only one of the most frequent diseases in humans and livestock, but also one of the top ten causes of
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Published 21 Nov 2018

Synthesis of pyrrolidine-based hamamelitannin analogues as quorum sensing inhibitors in Staphylococcus aureus

  • Jakob Bouton,
  • Kristof Van Hecke,
  • Reuven Rasooly and
  • Serge Van Calenbergh

Beilstein J. Org. Chem. 2018, 14, 2822–2828, doi:10.3762/bjoc.14.260

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  • , Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA 10.3762/bjoc.14.260 Abstract Interfering with bacterial cell-to-cell communication is a promising strategy to combat antimicrobial resistance. The natural
  • ; quorum sensing; Staphylococcus aureus; Introduction Antimicrobial resistance is rapidly becoming a global threat [1][2]. It is estimated that worldwide, at least 700 000 people die every year from drug-resistant strains of common bacterial infections. Strategies to deal with the global antimicrobial
  • resistance problem need to be multifactorial. Next to disease prevention and the development of new antibiotics, it is essential to investigate innovative strategies to combat bacterial infections [3][4]. Recently, targeting bacterial virulence has gained a lot of attention [5][6][7]. It has been
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Published 12 Nov 2018

Synthesis and biological evaluation of 1,2-disubstituted 4-quinolone analogues of Pseudonocardia sp. natural products

  • Stephen M. Geddis,
  • Teodora Coroama,
  • Suzanne Forrest,
  • James T. Hodgkinson,
  • Martin Welch and
  • David R. Spring

Beilstein J. Org. Chem. 2018, 14, 2680–2688, doi:10.3762/bjoc.14.245

Graphical Abstract
  • chemical probes. It has been proposed that such a strategy may perturb bacterial virulence and pathogenicity associated with QS, thus conferring a therapeutic benefit, without applying a selection pressure for resistance [6]. Whilst recent experiments suggest that resistance may still emerge, it has been
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Published 19 Oct 2018

Non-native autoinducer analogs capable of modulating the SdiA quorum sensing receptor in Salmonella enterica serovar Typhimurium

  • Matthew J. Styles and
  • Helen E. Blackwell

Beilstein J. Org. Chem. 2018, 14, 2651–2664, doi:10.3762/bjoc.14.243

Graphical Abstract
  • bacteriostatic chemotherapies to treat infection imposes evolutionary pressures that drive rapid resistance development and spread within and among bacterial populations [2][3]. Antibiotic resistant clinical isolates have been observed for almost every known antibiotic, and the pace of new antibiotic discovery
  • has lagged behind [4]. In recent years, non-bacteriocidal approaches have emerged as a new therapeutic strategy to treat infection with potentially a lesser propensity for resistance development and spread [4][5][6]. Interfering with the regulation of virulence phenotypes represents one such approach
  • ) operon; PefI negatively regulates the pef operon and SrgA is a disulfide oxidoreductase involved in correctly folding PefA, a fimbrial subunit [33]. The functions of SrgB-D are unknown [28]. SrgE is a type III secreted effector, but its target is unknown [19]. Lastly, rck (resistance to complement
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Published 17 Oct 2018

The design and synthesis of an antibacterial phenothiazine–siderophore conjugate

  • Abed Tarapdar,
  • James K. S. Norris,
  • Oliver Sampson,
  • Galina Mukamolova and
  • James T. Hodgkinson

Beilstein J. Org. Chem. 2018, 14, 2646–2650, doi:10.3762/bjoc.14.242

Graphical Abstract
  • antibacterial agents. Keywords: NDH-2; phenothiazine; siderophore; siderophore–antibiotic; siderophore conjugate; Introduction One of the biggest challenges facing the modern society is antibiotic resistance and the prospect of current antibiotics becoming near redundant against previously treatable
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Published 16 Oct 2018

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

  • Christian Schütz and
  • Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

Graphical Abstract
  • recent years, attempts to raise public awareness on antimicrobial resistance (AMR) and the large threat that it poses towards modern health standards have been made [1]. It is an alarming notion that at an increasing rate of available treatment options proves ineffective in eradicating bacterial
  • processes of the bacterial cell, ‘antivirulence’ strategies aim at abolishing pathogenic features without affecting cell viability, providing the basis for a lower drug-induced selection pressure [5][8][9]. Hence, a reduced rate of resistance development is expected [9]. A clinical proof-of-concept for this
  • disruption of the Pseudomonas quinolone signal quorum sensing system (pqs QS). Review Antimicrobial resistance and clinical relevance of Pseudomonas aeruginosa P. aeruginosa is one of the threatening ESKAPE pathogens and has regularly been attributed with the label ‘superbug’ [11]. In 2017, the World Health
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Published 15 Oct 2018

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

  • Matthew B. Calvert,
  • Varsha R. Jumde and
  • Alexander Titz

Beilstein J. Org. Chem. 2018, 14, 2607–2617, doi:10.3762/bjoc.14.239

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  • -Braunschweig, Germany Department of Pharmacy, Saarland University, Saarbrücken, Germany 10.3762/bjoc.14.239 Abstract The rapid development of antimicrobial resistance is threatening mankind to such an extent that the World Health Organization expects more deaths from infections than from cancer in 2050 if
  • for disarming pathogens. Furthermore, it is believed that this new approach is less susceptible towards resistance development. In this review, recent examples of anti-infective compounds acting on several types of bacterial targets, e.g., adhesins, toxins and bacterial communication, are described
  • . Keywords: antimicrobial resistance; bacterial adhesins; bacterial toxins; pathoblockers; quorum sensing; Review 1. Antimicrobial resistance crisis for bacterial infections The current crisis caused by antimicrobial resistance [1][2] demands new strategies to fight infections. Antibiotics have served as
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Published 11 Oct 2018

Impact of Pseudomonas aeruginosa quorum sensing signaling molecules on adhesion and inflammatory markers in endothelial cells

  • Carmen Curutiu,
  • Florin Iordache,
  • Veronica Lazar,
  • Aurelia Magdalena Pisoschi,
  • Aneta Pop,
  • Mariana Carmen Chifiriuc and
  • Alina Maria Hoban

Beilstein J. Org. Chem. 2018, 14, 2580–2588, doi:10.3762/bjoc.14.235

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  • compromised individuals and in patients with bronchiectasis or cystic fibrosis. The infections become chronic, as P. aeruginosa develops resistance to conventional antibiotics due to its ability to produce virulence factors and modulate immune defenses by quorum sensing (QS) and biofilm production
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Published 05 Oct 2018

Comparative cell biological study of in vitro antitumor and antimetastatic activity on melanoma cells of GnRH-III-containing conjugates modified with short-chain fatty acids

  • Eszter Lajkó,
  • Sarah Spring,
  • Rózsa Hegedüs,
  • Beáta Biri-Kovács,
  • Sven Ingebrandt,
  • Gábor Mező and
  • László Kőhidai

Beilstein J. Org. Chem. 2018, 14, 2495–2509, doi:10.3762/bjoc.14.226

Graphical Abstract
  • . Malignant melanoma, despite the improving chemotherapeutic and surgical strategies, remains the leading cause of skin cancer deaths. The strong ability to disseminate metastases and to develop resistance to chemotherapy results in poor prognosis especially in advanced cases [23]. The expression GnRH-R was
  • anticancer drug resistance as they are co-administrated with other chemotherapeutics [29][30]. Nevertheless, there is some controversy about the effects of short-chain fatty acids on the metastatic ability of melanoma cells, since both pro-invasive [31] and anti-invasive [29][32] activities have been
  • junctions, (ii) the seal resistance related to the cleft height between the cell and the electrode surface as well as (iii) the membrane capacitance correlated well with the amount of attached membrane area. The stronger adhesion could be due to a decrease in the cleft height, without any change in the
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Published 26 Sep 2018

Synthesis of a leopolic acid-inspired tetramic acid with antimicrobial activity against multidrug-resistant bacteria

  • Luce Mattio,
  • Loana Musso,
  • Leonardo Scaglioni,
  • Andrea Pinto,
  • Piera Anna Martino and
  • Sabrina Dallavalle

Beilstein J. Org. Chem. 2018, 14, 2482–2487, doi:10.3762/bjoc.14.224

Graphical Abstract
  • , is an imperative goal to stay ahead of the evolution of antibiotic resistance. Herein we report the synthesis of a 3-decyltetramic acid analogue of the ureido dipeptide natural antibiotic leopolic acid A. The key step in the synthetic strategy is an intramolecular Lacey–Dieckmann cyclization reaction
  • agar plates (Tryptic Soy Agar plus 5% defibrinated sheep blood, Microbiol, Italy) to obtain pure cultures [29]. The isolated colonies were used to assess the phenotypic profile of antimicrobial resistance. For this purpose, the Kirby Bauer disk diffusion method was used in accordance to Clinical
  • strains, oxacillin was also tested to assess methicillin-resistance (see Table S1, Supporting Information File 1, for details). After incubation, 30 strains of S. pseudintermedius revealed resistance phenoptype to three or more pharmacological categories and were considered multidrug resistant (MDR) [31
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Published 24 Sep 2018

Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

  • Kai Zhang,
  • Jiarong Li,
  • Honglin Liu,
  • Haiyou Wang and
  • Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

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  • macrolide compounds, such as modification of the macrolide and the branched chain glycosyl residue, and replacement of the sugar group, are in the limelight [16][17]. The unique macrolide structure of spinosyns and the efficient appearance of resistance in some insect pests have prompted further exploration
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Published 04 Sep 2018

Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3+ + 2]-cycloaddition/rearrangement reactions

  • Lin-bo Luan,
  • Zi-jie Song,
  • Zhi-ming Li and
  • Quan-rui Wang

Beilstein J. Org. Chem. 2018, 14, 1826–1833, doi:10.3762/bjoc.14.155

Graphical Abstract
  • examples of such clinically drugs having enhanced effects on the neurotransmitter γ-aminobutyric acid (GABA) at the GABAA receptor and low toxicity (Figure 1) [15]. Although 1,4-benzodiazepines are widely prescribed medicines, side effects like drowsiness, drug resistance, addiction and withdrawal
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Published 18 Jul 2018

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

  • Bimal Koirala,
  • Robert A. Hillman,
  • Erin K. Tiwold,
  • Michael A. Bertucci and
  • Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

Graphical Abstract
  • (CSP), to acquire antibiotic resistance and establish an infection. In this work, we sought to define the binding pockets within the ComD1 receptor used for binding the hydrophobic side-chain residues in CSP1 through the introduction of highly-conservative point mutations within the peptide
  • . Optimization of these binding interactions could lead to the development of highly potent CSP-based QS modulators while the inclusion of non-natural amino acids within the CSP sequence would confer resistance to protease degradation, a requirement for drug candidates. Keywords: binding surface; competence
  • as the competence regulon, is centered on the competence stimulating peptide (CSP, Figure 1). S. pneumoniae utilizes the regulon to become competent and acquire antibiotic resistance from the environment, initiate its attack on the human host through virulence factor production, and protect itself
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Published 16 Jul 2018

Natural and redesigned wasp venom peptides with selective antitumoral activity

  • Marcelo D. T. Torres,
  • Gislaine P. Andrade,
  • Roseli H. Sato,
  • Cibele N. Pedron,
  • Tania M. Manieri,
  • Giselle Cerchiaro,
  • Anderson O. Ribeiro,
  • Cesar de la Fuente-Nunez and
  • Vani X. Oliveira Jr.

Beilstein J. Org. Chem. 2018, 14, 1693–1703, doi:10.3762/bjoc.14.144

Graphical Abstract
  • conventional chemotherapy [11][12]. ACPs are promising anticancer compounds as they offer advantages such as higher specificity and lower incidence of acquired resistance in comparison to existing therapies [12][13][14]. ACPs derive from various sources and consequently share low homology [15][16][17][18
  • -negative bacteria, fungi, and protozoa. However, both peptides presented high hemolytic activity, which limited their use as potential therapies. Torres et al. synthesized Dec-NH2 analogs with single and double substitutions, which exhibited increased resistance to degradation and lower hemolytic activity
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Published 06 Jul 2018

Lanyamycin, a macrolide antibiotic from Sorangium cellulosum, strain Soce 481 (Myxobacteria)

  • Lucky S. Mulwa,
  • Rolf Jansen,
  • Dimas F. Praditya,
  • Kathrin I. Mohr,
  • Patrick W. Okanya,
  • Joachim Wink,
  • Eike Steinmann and
  • Marc Stadler

Beilstein J. Org. Chem. 2018, 14, 1554–1562, doi:10.3762/bjoc.14.132

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  • . Additionally, the treatment and management of viral and bacterial diseases is complicated by increasing rates of multidrug resistance. Hence, the need for new chemical scaffolds urgently required to increase the chemical diversity of drugs, especially to obtain antibiotics that overcome resistance by new modes
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Published 26 Jun 2018

Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting

  • Jonas Weidner,
  • Stefan Barwe,
  • Kirill Sliozberg,
  • Stefan Piontek,
  • Justus Masa,
  • Ulf-Peter Apfel and
  • Wolfgang Schuhmann

Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121

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  • was determined by means of a pH electrode for high alkaline solutions (Dr. Kornder Anlagen- und Messtechnik, Germany) to be 14. RDE measurements were performed at a rotation speed of 1600 rpm. In order to correct the potential for the uncompensated electrolyte resistance, electrochemical impedance
  • an EIS was recorded to determine the uncompensated electrolyte resistance and the potential was corrected accordingly. The conditioning of the catalyst was performed by cyclic voltammetry with 20 cycles between 0.97 V vs RHE and 1.43 V vs RHE with a scan rate of 100 mV s−1. The LSVs were measured
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Published 13 Jun 2018
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