LC-MS/MS Strategy Using Substructure Searching for the Annotation of Cyanopeptide Classes: Implications for New...

Area of Science:

• Environmental Science
• Ecotoxicology
• Natural Product Chemistry

Background:

• Cyanobacterial harmful algal blooms (cyanoHABs) pose ecological and public health risks.
• Current monitoring often focuses on specific toxins like microcystins, neglecting other bioactive metabolites.
• The full range of metabolites produced by cyanoHABs remains undercharacterized.

Purpose of the Study:

• To identify and characterize novel bioactive metabolites from cyanoHABs.
• To develop and apply advanced analytical methods for comprehensive cyanopeptide profiling.
• To assess the ecological and toxicological relevance of identified compounds.

Main Methods:

• Isolation and structural elucidation of compounds using spectrometric and spectroscopic techniques.
• Analysis of liquid chromatography-tandem mass spectrometry (LC-MS/MS) data with Global Natural Products Social Molecular Networking 2 (GNPS2).
• Bioactivity screening, including neutrophil elastase inhibition assays.

Main Results:

• Two new micropeptins (1 and 2) and ferintoic acid C (3) were isolated and characterized.
• GNPS2 facilitated the annotation of diverse cyanopeptide classes and modifications.
• Micropeptin 1 showed moderate neutrophil elastase inhibition.
• Field samples revealed recurring micropeptins, but not microcystins, in Lake Erie blooms.

Conclusions:

• Cyanobacterial blooms produce a wider array of bioactive metabolites than commonly monitored.
• Expanded monitoring of non-microcystin cyanopeptides is crucial for accurate bloom hazard assessment.
• These findings challenge microcystin-centric risk evaluations and highlight the need for broader chemical surveillance.