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Cationic amphipathic peptoid oligomers as antimicrobial peptide mimics

Abstract : Living organisms produce antimicrobial peptides (AMPs) to protect themselves against microbes.The growing problem of antimicrobial resistance calls for new therapeutic strategies and the natural AMPs have shown ground-breaking potential to address that issue. They show broad-spectrum activity and their main mechanism of action by bacterial cell membrane disruption implies low emergence of resistance which makes them potent candidates for replacing conventional antibiotics. Nevertheless, few hurdles are impeding their use, notably poor bioavailability profile. Some of these limitations can be overcome by developing peptidomimetics of AMPs which exhibit antibacterial activities together with enhanced therapeutic potential. Peptoids (i.e. N-alkyl glycine oligomers) adopting cationic amphipathic helical structures are mostly competent AMP mimetics. From a conformational point of view, peptoids are fundamentally more flexible than peptides primarily due to the cis/trans isomerism of N,N-disubstituted amides but studies in this area have shown that cis amide conformation can be controlled by careful choice of side-chain to set a PolyProline I-type helical structure of peptoids. In this thesis, the genesis of novel amphipathic cationic peptoids carrying cis-directing tert-butyl and/or triazolium-type side-chains and their untapped potential to act against bacteria will be discussed comprehensively. First, the solutionphase synthesis of tert-butyl-based oligomers was developed. Second, novel method of solid-phase submonomer synthesis was optimised to access 1,2,3-triazolium-based oligomers. Then, the synthesised cationic oligomers were evaluated for their antibacterial potential, followed by antibiofilm activity and cell selectivity assays. In the end, to have insights on the mode of action of amphipathic peptoids, microscopy was carried out.
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Radhe Shyam. Cationic amphipathic peptoid oligomers as antimicrobial peptide mimics. Organic chemistry. Université Clermont Auvergne, 2018. English. ⟨NNT : 2018CLFAC048⟩. ⟨tel-02060354⟩

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