Diagnostic Fragmentation Filtering for Cyanopeptolin Detection


McDonald, K., Renaud, J.B., Pick, F.R., Miller, J.D., Sumarah, M.W., McMullin, D.R. (2021). Diagnostic Fragmentation Filtering for Cyanopeptolin Detection. Environmental Toxicology and Chemistry, [online] 40(4), 1087-1097. http://dx.doi.org/10.1002/etc.4941

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Algae are able to produce chemicals that are used to help with their survival in the environment. Some of these chemicals are toxic to fish and animals if they come in contact with them. In this study we developed a new method that utilizes the properties of these chemicals to screen surface water samples for all possible versions. The method was very effective at detecting these toxins and we were even able to find a number of new ones that have not previously been described.


Cyanobacteria are ubiquitous photosynthetic prokaryotes that produce structurally diverse bioactive metabolites. Although microcystins are extensively studied, other cyanopeptides produced by common bloom-forming species have received little attention. Cyanopeptolins are a large cyanopeptide group that contain a characteristic 3-amino-6-hydroxy-2-piperidone (Ahp) moiety. In the present study we used diagnostic fragmentation filtering (DFF), a semitargeted liquid chromatography-tandem mass spectrometry (MS/MS) product ion filtering approach, to investigate cyanopeptolin diversity from 5 Microcystis strains and 4 bloom samples collected from lakes in Ontario and Quebec, Canada. Data processing by DFF was used to search MS/MS data sets for pairs of diagnostic product ions corresponding to cyanopeptolin partial sequences. For example, diagnostic product ions at m/z 150.0912 and 215.1183 identified cyanopeptolins with the NMe-Tyr–Phe–Ahp partial sequence. Forty-eight different cyanopeptolins, including 35 new variants, were detected from studied strains and bloom samples. Different cyanopeptolin profiles were identified from each sample. We detected a new compound, cyanopeptolin 1143, from a bloom and elucidated its planar structure from subsequent targeted MS/MS experiments. Diagnostic fragmentation filtering is a rapid, easy-to-perform postacquisition metabolomics strategy for inferring structural features and prioritizing new compounds for further study and dereplication. More work on cyanopeptolin occurrence and toxicity is needed because their concentrations in freshwater lakes after blooms can be similar to those of microcystins. Environ Toxicol Chem 2021;40:1087–1097. © 2020 SETAC.

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