Microcystin-lr detected in a low molecular weight fraction from a crude extract of Zoanthus sociatus

Cnidarian constitutes a great source of bioactive compounds. However, research involving peptides from organisms belonging to the order Zoanthidea has received very little attention, contrasting to the numerous studies of the order Actiniaria, from which hundreds of toxic peptides and proteins have been reported. In this work, we performed a mass spectrometry analysis of a low molecular weight (LMW) fraction previously reported as lethal to mice. The low molecular weight (LMW) fraction was obtained by gel filtration of a Zoanthus sociatus (order Zoanthidea) crude extract with a Sephadex G-50, and then analyzed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry (MS) in positive ion reflector mode from m/z 700 to m/z 4000. Afterwards, some of the most intense and representative MS ions were fragmented by MS/MS with no significant results obtained by Protein Pilot protein identification software and the Mascot algorithm search. However, microcystin masses were detected by mass-matching against libraries of non-ribosomal peptide database (NORINE). Subsequent reversed-phase C18 HPLC (in isocratic elution mode) and mass spectrometry analyses corroborated the presence of the cyanotoxin Microcystin-LR (MC-LR). To the best of our knowledge, this finding constitutes the first report of MC-LR in Z. sociatus, and one of the few evidences of such cyanotoxin in cnidarians. © 2017 by the authors. Licensee MDPI, Basel, Switzerland. Dany Dom?nguez P?rez was supported by a Ph.D. grant (SFRH/BD/80592/2011) from the Portuguese Foundation for Science and Technology (FCT?Funda??o para a Ci?ncia e a Tecnologia, Portugal). Armando A Rodr?guez was supported by an Alexander von Humboldt postdoctoral fellowship (3.2-KUB/1153731 STP). We are grateful to Carlos Manlio Diaz-Garc?a (from Department of Neurobiology, Harvard Medical School, Boston, MA, USA) for his useful comments and to Carlos Varela (Department of Biological Sciences, Florida International University (FIU), FL, USA) for providing Z. sociatus specimens. This study was funded in part by the Strategic Funding UID/Multi/04423/2013 through national funds provided by FCT and the European Regional Development Fund (ERDF) in the framework of the program PT2020, by the European Structural and Investment Funds (ESIF) through the Competitiveness and Internationalization Operational Program?COMPETE 2020 and by National Funds through the FCT under the project PTDC/AAG-GLO/6887/2014 (POCI-01-0124-FEDER-016845), and by the Structured Programs of R&D&I INNOVMAR?Innovation and Sustainability in the Management and Exploitation of Marine Resources (NORTE-01-0145-FEDER-000035, Research Line NOVELMAR) and MarInfo?Integrated Platform for Marine Data Acquisition and Analysis (NORTE-01-0145-FEDER-000031), and funded by the Northern Regional Operational Program (NORTE2020) through the ERDF.