Thesis

Biologically active secondary metabolites : investigation of marine organism and microorganisms

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Awarding institution
  • University of Strathclyde
Date of award
  • 2013
Thesis identifier
  • T13564
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • Secondary metabolites from the marine sponge and an associated marine microorganism were investigated using state of the art high resolution mass spectrometry and nuclear magnetic resonance spectroscopy to conduct metabolomic dereplication and structure elucidation of biologically active metabolites. The isolation and purification of bioactive compounds from the marine sponge Callyspongia aff. implexa was undertaken using a bioassay-guided purification scheme. Structure elucidation of the purified compounds was accomplished through spectroscopic and spectromitric methods including NMR and MS. Dereplication was conducted on the bioactive fractions corroborating the structures of previously isolated compounds. Three compounds were isolated; namely β-sitosterol, A37-2-B1, a 3, 7-hyroxyl-sterol with an acetylene side chain as well as A45-3-3, an polyacetylene which was also proven to be present in the bioactive fractions. Metabolomics tools were applied to dereplicate extracts of the marine-associated bacterium Actinokineospora EG49 which led to the isolation of an anti-trypanosomal quinone, which resembles angucycline metabolites. Structure elucidation of quinone metabolites, namely EG49D and EG49F4B, from Actinokineospora EG49 was conducted. Supervised Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA) was used to choose the best culture method to optimise the production of the bioactive metabolite. The production of quorum sensing (QS) signalling molecules, Acyl Homoserine Lactones (AHLs) by a panel of Gram-negative bioluminescent bacteria was investigated using high resolution tandem mass spectrometry. This was used to complement and validate results obtained from a traditional TLC screening approach in which the long acyl-chain AHLs are difficult to visualise. Preliminarily investigation of the possible relationships between the quorum sensing signals and cryptic secondary metabolites was also carried out. A group of "candidate" compounds that may be involved in the QS regulation process was created using supervised Orthogonal Partial Least Square-Discriminant Analysis for use in further investigations for antibiotics.
Resource Type
DOI
Date Created
  • 2013
Former identifier
  • 1001613

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