Tackling antimicrobial resistance through two novel methods: repurposing vanoxerine as a novel anti-tubercular drug; and silencing virulence in Pseudomonas aeruginosa through inhibition of PqsR

Grossman, Scott (2018) Tackling antimicrobial resistance through two novel methods: repurposing vanoxerine as a novel anti-tubercular drug; and silencing virulence in Pseudomonas aeruginosa through inhibition of PqsR. MRes thesis, University of Nottingham.

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Abstract

The antimicrobial resistance crisis is one which will persist and worsen without intervention. This thesis looks to explore two innovative research areas in order to develop new antibiotics and stem the rise in antibiotic resistance. The first project looked at the potential to repurpose the former central nervous system (CNS) drug candidate vanoxerine into an anti-tubercular compound. Previous work has suggested that vanoxerine acts as a prodrug in mycobacteria and interacts with the monooxygenase enzymes Rv0565c and Rv3518c of Mycobacterium tuberculosis (Mtb). In this work a MIC50 assay was utilised to complete a structure-activity relationship (SAR) study and prove that vanoxerine is hydroxylated in vivo to its active form. Further to this, a global lipid analysis was completed suggesting that when treated with analogues of vanoxerine a lipid biosynthetic pathway was halted, though the lipid itself could not be identified. Although mass spectrometry was employed to identify changes in lipid concentrations at varying concentrations of drug, no trends were clear. However, the mass spectrometry data did indicate that analogues of vanoxerine were also hydroxylated in vivo, furthering the original hypothesis.

A further novel method for targeting antimicrobial resistance is the targeting of virulence systems. By inhibiting virulence but not affecting cell viability, no selection pressures are put on the pathogenic population. This enables the immune system to clear the infection without the host cells from being harmed by the release of toxins whilst preventing resistant subpopulations from dominating. In this work, a series of compounds were synthesised to act as antagonists to the protein PqsR, the autoinductive regulator of the quorum sensing system pqs in Pseudomonas aeruginosa. This system is associated with a range of effects including the synthesis of the toxin pyocyanin and the biofilm formation. Therefore, interference with these pathways may attenuate P. aeruginosa without encouraging selection of resistant bacteria. A biosensor reporter assay provided semiquantitative data suggesting that the majority of synthesised compounds reduced expression of the pqs system. Moreover, IC50 testing has been initiated, providing quantitative data on the potency of the synthesised series.

Item Type: Thesis (University of Nottingham only) (MRes)
Supervisors: Stocks, Michael
Alderwick, Luke
Keywords: Antimicrobial resistance; Antibiotic resistance; Virulence systems
Subjects: Q Science > QR Microbiology
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 55397
Depositing User: Grossman, Scott
Date Deposited: 11 Apr 2019 14:31
Last Modified: 07 May 2020 13:45
URI: http://eprints.nottingham.ac.uk/id/eprint/55397

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