The frequency and severity of cyanobacterial harmful algal blooms (CHABs) in our lakes and reservoirs are increasing with alarming results. These blooms produce a variety of potent toxins such as the microcystin family of hepatotoxins that comprise a group of over 70 cyclic peptides with many unique chemical features and a range of biological activities. However, only 4 of these are routinely monitored by regulatory agencies. Additionally, our group and others have discovered many new compounds produced by these bloom-forming species that have unusual chemical structures and potent biological activities that go undetected in current targeted screening methodologies. UPLC-HR-ToF-MS based untargeted metabolomics analysis combined with traditional chromatographic isolation and structure elucidation is a powerful approach to understand the chemical production and correlated biological activity of both known toxins and other biologically active compounds produced by these CHAB species. In this study, we analyzed the organic extracts of laboratory cultures of different species of HAB-forming cyanobacteria using untargeted UPLC-HR-Tof-MSe data acquisition and Progenesis multivariate analysis. From this analysis and subsequent isolation and structure determination, we are discovering many new cyanopeptides with a variety of biological activities. Select laboratory strains were also cultured in pre-cursor labeled media to create a parallel library of these high-value toxins completely labeled with 15N isotope for increased monitoring sensitivity and accurate structure assignment through fragmentation analysis. We then built a searchable electronic library of known toxins as well as these new compounds annotated with structure and chromatographic information. Concurrently, we analyzed a series of environmental blooms from the southeastern North Carolina region as well as from a massive bloom in Florida with similar methodology and were able to correctly identify many of the same compounds in these environmental samples. Results of the analysis, structures, 15N labeling, and biological activities will be presented.

Expanding targets of UPLC-ToF-MS metabolomics and 15N labeling in Cyanobacterial Harmful Algal Bloom (CHAB) research: Microcystins and beyond

253rd National Meeting (2017)

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