Grauslys, Arturas (2016) Development of approaches for screening antimalarial compounds based on their modes of action. PhD thesis, University of Warwick.

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Abstract

Malaria is an infectious tropical disease responsible for hundreds of thousands of deaths every year. It is caused by a parasite from genus Plasmodium of which falciparum is the most deadly and the focus of this study. The limited number of currently available drugs are further threatened by the rising frequency of resistance. This has greatly emphasised the need for new drugs with novel modes of action. The current drug development pipelines rely on large scale compound library screens for antimalarial effect. Computational chemometric methods are then used for selecting promising hits for further investigation. Such analyses however rely on indirect characterisation of compound effects. In this project we investigated three approaches aimed at developing compound screening assays based on compound effects on live cells. The first two approaches relied on metabolomics techniques. Based on the assumption that the drug-induced metabolic changes in the malaria parasite could be uniquely assigned to the drug mode of action we hypothesised that if such metabolic states could be measured they could be used to cluster the compounds into groups based on their modes of action. By comparison to well-established antimalarials the clusters of novel compounds could then be characterised and novel compound clusters identified. The third method relied on the phenotypic information for drug exposed malaria parasites derived from the analysis of fluorescent microscopy images. This assay aimed at characterising the modes of action of the compounds as well as the speed of kill. The first method investigated was based on metabolic fingerprinting using Fourier transform infrared spectroscopy. The sample preparation and data acquisition protocols were developed and tested. The results suggested that the sensitivity of the technique was insufficient for the detection of drug induced effects in P. falciparum. Next a nuclear magnetic resonance (NMR) spectroscopy-based method was developed. While the method was promising in terms of high throughput capabilities, consistency and the breadth of information posed a series of issues, mainly associated with sensitivity. In the absence of a suitable automated data processing solution a custom software “ProcNMR" was developed and used to process the data collected in the experiments. A full experimental procedure was developed and tested, however the NMR sensitivity issues, exacerbated by the complex intraerythrocytic nature of P. falciparum resulted in suboptimal outputs. Lastly a high content imaging-based technique was investigated. Data processing and predictive analysis methods were developed and implemented. A pilot experiment was used to demonstrate the potential of the technique to discriminate between fast and slow acting drugs. The compounds of the “Malaria Box" were screened using this technique and a group of fast acting compounds identified.

Item Type:	Thesis (PhD)
Subjects:	R Medicine > RC Internal medicine
Library of Congress Subject Headings (LCSH):	Antimalarials, Malaria -- Prevention, Medical screening
Official Date:	February 2016
Dates:	Date Event February 2016 Submitted
Institution:	University of Warwick
Theses Department:	Systems Biology Doctoral Training Centre
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Wild, David ; Ward, Stephen
Format of File:	pdf
Extent:	xvii, 175 leaves : illustrations
Language:	eng

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