Chemical diversity and biological activity assessment of Benthic Cyanobacteria from the west of Ireland

Toxins produced by cyanobacteria emerge as significant hazards to the well-being of humans, animals, and aquatic ecosystems. Human exposure to these toxins arises primarily through the consumption of contaminated water or through direct contact, particularly in instances of cyanobacterial bloom events. The escalation of harmful cyanobacterial blooms on a global scale is becoming a major concern, as our understanding of the toxin production and metabolomes associated with these newly emerging and widespread blooms remains limited. Cyanobacterial blooms in Ireland are no exception due to the occurrence of widespread lakes. On the other hand, the metabolome of these cyanobacteria represents an unexplored repository of bioactive metabolites with the potential to provide valuable applications. Consequently, the investigation of cyanobacterial accumulations in freshwater ecosystems in Ireland not only holds the potential to reveal new bioactive compounds but also offers an opportunity to confront the emerging threats posed by these microorganisms. This PhD thesis describes the first results of a deep chemical investigation of major benthic cyanobacterial accumulations from some freshwater lakes in the West of Ireland. Chapter two describes the sample collection and prioritisation protocol of samples achieved through a biological screening, chemical profiling and retrospective toxin analysis protocol. Chapter three describes the isolation and structure elucidation of the new Micropeptin LOF941, Micropeptin LOF925 and Micropeptin LOF953 from a Microcoleus autumnalis-dominated biofilm collected from Lough O’Flynn, Co. Roscommon, alongside their evaluation as antioxidative agents and proposition of chemical structures of minor micropeptin analogues using a tandem mass spectrometry/molecular networking workflow. Chapter four describes the isolation and structure elucidation of two new [7.7]paracyclophane derivatives containing an unusual α-L-rhamnose sugar moiety, and their evaluation as antimicrobial agents. Chapter five describes a series of new bisindole alkaloids, the Urlárins, isolated from cyanobacteria collected from Lough Urlár, Co. Mayo, and their activity as cytotoxic compounds. This first deep chemical investigation of some Irish freshwater cyanobacteria underscores the importance of ongoing assessments, encompassing both potential beneficial applications and considerations of toxicity.

Funder

School of Chemistry, University of Galway

Publisher

University of Galway

Rights

Attribution-NonCommercial-NoDerivatives 4.0 International

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Collections

University of Galway Theses (PhD Theses)