24 results found
Haque M, Flack T, Singh R, et al., 2023, Aromatic oligoesters as novel helix mimetic scaffolds, Bioorganic and Medicinal Chemistry, Vol: 87, ISSN: 0968-0896
The design, synthesis, and conformational analysis of a novel aromatic oligoester helix mimetic scaffold is reported. A range of amino acid-type side-chain functionality can be readily incorporated into monomer building blocks over three facile synthetic steps. Analysis of representative dimers revealed a stable conformer capable of effective mimicry of a canonical α-helix and the scaffold was found to be surprisingly stable to degradation in aqueous solutions at acidic and neutral pH.
Yahiya S, Saunders CN, Hassan S, et al., 2023, A novel class of sulphonamides potently block malaria transmission by targeting a Plasmodium vacuole membrane protein, Disease Models & Mechanisms, Vol: 16, Pages: 1-20, ISSN: 1754-8403
Phenotypic cell-based screens are critical tools for discovering candidate drugs for development, yet identification of the cellular target and mode of action of a candidate drug is often lacking. Using an imaging-based screen, we recently discovered an N-[(4-hydroxychroman-4-yl)methyl]-sulphonamide (N-4HCS) compound, DDD01035881, that blocks male gamete formation in the malaria parasite life cycle and subsequent transmission of the parasite to the mosquito with nanomolar activity. To identify the target(s) of DDD01035881, and of the N-4HCS class of compounds more broadly, we synthesised a photoactivatable derivative, probe 2. Photoaffinity labelling of probe 2 coupled with mass spectrometry identified the 16 kDa Plasmodium falciparum parasitophorous vacuole membrane protein Pfs16 as a potential parasite target. Complementary methods including cellular thermal shift assays confirmed that the parent molecule DDD01035881 stabilised Pfs16 in lysates from activated mature gametocytes. Combined with high-resolution, fluorescence and electron microscopy data, which demonstrated that parasites inhibited with N-4HCS compounds phenocopy the targeted deletion of Pfs16 in gametocytes, these data implicate Pfs16 as a likely target of DDD01035881. This finding establishes N-4HCS compounds as being flexible and effective starting candidates from which transmission-blocking antimalarials can be developed in the future.
Vieira de Castro G, Worm D, Grabe G, et al., 2022, Characterisation of the key determinants of Phd antitoxin mediated Doc toxin inactivation in Salmonella, ACS Chemical Biology, Vol: 17, Pages: 1598-1606, ISSN: 1554-8929
In the search for novel antimicrobial therapeutics, toxin-antitoxin (TA) modules are promising yet underexplored targets for overcoming antibiotic failure. The bacterial toxin Doc has been associated with the persistence of Salmonella in macrophages, enabling its survival upon antibiotic exposure. After developing a novel method to produce the recombinant toxin, we have used antitoxin-mimicking peptides to thoroughly investigate the mechanism by which its cognate antitoxin Phd neutralizes the activity of Doc. We reveal insights into the molecular detail of the Phd–Doc relationship and discriminate antitoxin residues that stabilize the TA complex from those essential for inhibiting the activity of the toxin. Coexpression of Doc and antitoxin peptides in Salmonella was able to counteract the activity of the toxin, confirming our in vitro results with equivalent sequences. Our findings provide key principles for the development of chemical tools to study and therapeutically interrogate this important class of protein–protein interactions.
Kahan R, Worm D, Vieira de Castro G, et al., 2021, Modulators of protein–protein interactions as antimicrobial agents, RSC Chemical Biology, Vol: 2, Pages: 387-409, ISSN: 2633-0679
Protein–Protein interactions (PPIs) are involved in a myriad of cellular processes in all living organisms and the modulation of PPIs is already under investigation for the development of new drugs targeting cancers, autoimmune diseases and viruses. PPIs are also involved in the regulation of vital functions in bacteria and, therefore, targeting bacterial PPIs offers an attractive strategy for the development of antibiotics with novel modes of action. The latter are urgently needed to tackle multidrug-resistant and multidrug-tolerant bacteria. In this review, we describe recent developments in the modulation of PPIs in pathogenic bacteria for antibiotic development, including advanced small molecule and peptide inhibitors acting on bacterial PPIs involved in division, replication and transcription, outer membrane protein biogenesis, with an additional focus on toxin–antitoxin systems as upcoming drug targets.
Rueda-Zubiaurre A, Yahiya S, Fischer O, et al., 2020, Structure-activity relationship studies of a novel class of transmission blocking antimalarials targeting male gametes., Journal of Medicinal Chemistry, Vol: 63, Pages: 2240-2262, ISSN: 0022-2623
Malaria is still a leading cause of mortality among children in the developing world, and despite the immense progress made in reducing the global burden, further efforts are needed if eradication is to be achieved. In this context, targeting transmission is widely recognized as a necessary intervention towards that goal. After carrying out a screen to discover new transmission-blocking agents, herein we report our medicinal chemistry efforts to study the potential of the most robust hit, DDD01035881, as a male-gamete targeted compound. We reveal key structural features for the activity of this series and identify analogues with greater potency and improved metabolic stability. We believe this study lays the groundwork for further development of this series as a transmission blocking agent.
Flack T, Romain C, White A, et al., 2019, Design, synthesis and conformational analysis of oligobenzanilides as multi-facial alpha-helix mimetics, Organic Letters, Vol: 21, Pages: 4433-4438, ISSN: 1523-7052
The design, synthesis, and conformationalanalysis of an oligobenzanilide helix mimetic scaffold capableof simultaneous mimicry of two faces of an α-helix is reported.The synthetic methodology provides access to diversemonomer building blocks amenable to solid-phase assemblyin just four synthetic steps. The conformational flexibility ofmodel dimers was investigated using a combination of solidand solution state methodologies supplemented with DFTcalculations. The lack of noncovalent constraints allows forsignificant conformational plasticity in the scaffold, thuspermitting it to successfully mimic residues i, i+2, i+4, i+6, i+7, and i+9 of a canonical α-helix.
Delves M, Miguel-Blanco C, Matthews H, et al., 2018, A high throughput screen for next-generation leads targeting malaria parasite transmission, Nature Communications, Vol: 9, ISSN: 2041-1723
Spread of parasite resistance to artemisinin threatens current frontline antimalarial therapies, highlighting the need for new drugs with alternative modes of action. Since only 0.2–1% of asexual parasites differentiate into sexual, transmission-competent forms, targeting this natural bottleneck provides a tangible route to interrupt disease transmission and mitigate resistance selection. Here we present a high-throughput screen of gametogenesis against a ~70,000 compound diversity library, identifying seventeen drug-like molecules that target transmission. Hit molecules possess varied activity profiles including male-specific, dual acting male–female and dual-asexual-sexual, with one promising N-((4-hydroxychroman-4-yl)methyl)-sulphonamide scaffold found to have sub-micromolar activity in vitro and in vivo efficacy. Development of leads with modes of action focussed on the sexual stages of malaria parasite development provide a previously unexplored base from which future therapeutics can be developed, capable of preventing parasite transmission through the population.
Arrata I, Barnard A, Tomlinson DC, et al., 2017, Interfacing native and non-native peptides: using Affimers to recognise α-helix mimicking foldamers, Chemical Communications, Vol: 53, Pages: 2834-2837, ISSN: 1359-7345
Selection methods are used to identify Affimers that recognise α-helix mimicking N-alkylated aromatic oligoamides thus demonstrating foldamer and natural α-amino acid codes are compatible.
Azzarito V, Rowell P, Barnard A, et al., 2016, Probing Protein Surfaces: QSAR Analysis with Helix Mimetics, Chembiochem, Vol: 17, Pages: 768-773, ISSN: 1439-7633
α-Helix-mediated protein–protein interactions (PPIs) are important targets for small-molecule inhibition; however, generic approaches to inhibitor design are in their infancy and would benefit from QSAR analyses to rationalise the noncovalent basis of molecular recognition by designed ligands. Using a helix mimetic based on an oligoamide scaffold, we have exploited the power of a modular synthesis to access compounds that can readily be used to understand the noncovalent determinants of hDM2 recognition by this series of cell-active p53/hDM2 inhibitors.
Barnard A, Long K, Martin HL, et al., 2015, Selective and potent proteomimetic inhibitors of intracellular protein–protein interactions, Angewandte Chemie - International Edition, Vol: 54, Pages: 2960-2965, ISSN: 1433-7851
Inhibition of protein–protein interactions (PPIs) represents a major challenge in chemical biology and drug discovery. α-Helix mediated PPIs may be amenable to modulation using generic chemotypes, termed “proteomimetics”, which can be assembled in a modular manner to reproduce the vectoral presentation of key side chains found on a helical motif from one partner within the PPI. In this work, it is demonstrated that by using a library of N-alkylated aromatic oligoamide helix mimetics, potent helix mimetics which reproduce their biophysical binding selectivity in a cellular context can be identified.
The exploitation of multivalent ligands for the inhibition of protein–protein interactions has not yet been explored as a supramolecular design strategy. This is despite the fact that protein–protein interactions typically occur within the context of multi-protein complexes and frequently exploit avidity effects or co-operative binding interactions to achieve high affinity interactions. In this paper we describe preliminary studies on the use of a multivalent N-alkylated aromatic oligoamide helix mimetic for inhibition of p53/hDM2 and establish that protein dimerisation is promoted, rather than enhanced binding resulting from a higher effective concentration of the ligand.
Barnard A, Posocco P, Fermeglia M, et al., 2014, Double-degradable responsive self-assembled multivalent arrays - temporary nanoscale recognition between dendrons and DNA, ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 12, Pages: 446-455, ISSN: 1477-0520
Tschiche A, Staedtler AM, Malhotra S, et al., 2014, Polyglycerol-based amphiphilic dendrons as potential siRNA carriers for in vivo applications, JOURNAL OF MATERIALS CHEMISTRY B, Vol: 2, Pages: 2153-2167, ISSN: 2050-750X
Barnard A, Long K, Yeo DJ, et al., 2014, Orthogonal functionalisation of alpha-helix mimetics, ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 12, Pages: 6794-6799, ISSN: 1477-0520
Prabhakaran P, Barnard A, Murphy NS, et al., 2013, Aromatic Oligoamide Foldamers with a "Wet Edge" as Inhibitors of the -Helix-Mediated p53-hDM2 Protein-Protein Interaction, EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Vol: 2013, Pages: 3504-3512, ISSN: 1434-193X
Bromfield SM, Barnard A, Posocco P, et al., 2013, Mallard Blue: A High-Affinity Selective Heparin Sensor That Operates in Highly Competitive Media, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 135, Pages: 2911-2914, ISSN: 0002-7863
Barnard A, Smith DK, 2012, Self-Assembled Multivalency: Dynamic Ligand Arrays for High-Affinity Binding, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 51, Pages: 6572-6581, ISSN: 1433-7851
Ottaviani MF, Cangiotti M, Fiorani L, et al., 2012, Probing dendron structure and nanoscale self-assembly using computer-aided analysis of EPR spectra, NEW JOURNAL OF CHEMISTRY, Vol: 36, Pages: 469-476, ISSN: 1144-0546
Barnard A, Calderon M, Tschiche A, et al., 2012, Effects of a PEG additive on the biomolecular interactions of self-assembled dendron nanostructures, ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 10, Pages: 8403-8409, ISSN: 1477-0520
Barnard A, Posocco P, Pricl S, et al., 2011, Degradable Self-Assembling Dendrons for Gene Delivery: Experimental and Theoretical Insights into the Barriers to Cellular Uptake, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 133, Pages: 20288-20300, ISSN: 0002-7863
Fischer W, Quadir MA, Barnard A, et al., 2011, Controlled Release of DNA From Photoresponsive Hyperbranched Polyglycerols with Oligoamine Shells, MACROMOLECULAR BIOSCIENCE, Vol: 11, Pages: 1736-1746, ISSN: 1616-5187
Rodrigo AC, Barnard A, Cooper J, et al., 2011, Self-Assembling Ligands for Multivalent Nanoscale Heparin Binding, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 50, Pages: 4675-4679, ISSN: 1433-7851
Posocco P, Pricl S, Jones S, et al., 2010, Less is more - multiscale modelling of self-assembling multivalency and its impact on DNA binding and gene delivery, CHEMICAL SCIENCE, Vol: 1, Pages: 393-404, ISSN: 2041-6520
Barnard A, Dickson SJ, Paterson MJ, et al., 2009, Enantioselective lactate binding by chiral tripodal anion hosts derived from amino acids, ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 7, Pages: 1554-1561, ISSN: 1477-0520
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