The novel ovatoxin-g and isobaric palytoxin (so far referred to as putative palytoxin) from Ostreopsis cf. ovata (NW Mediterranean Sea): structural insights by LC-high resolution MSn

• Published in: Analytical and bioanalytical chemistry Vol. 407; no. 4; pp. 1191 - 1204
• Main Authors: García-Altares, María, Tartaglione, Luciana, Dell’Aversano, Carmela, Carnicer, Olga, de la Iglesia, Pablo, Forino, Martino, Diogène, Jorge, Ciminiello, Patrizia
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2015
• Subjects: Analytical Chemistry; Biochemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Food Science; Laboratory Medicine; Monitoring/Environmental Analysis; Research Paper; Palytoxin; Ovatoxin-g; cf; Putative palytoxin; LC-HRMS; Isobaric palytoxin
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-014-8338-y

Blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the Mediterranean Sea, since this species produces a wide range of palytoxin-like compounds listed among the most potent marine toxins. This study focused on two analogs of palytoxin found in cultures of six strains of O . cf. ovata isolated from the south of Catalonia (NW Mediterranean Sea). In addition to some already known ovatoxins, our strains produced two minor compounds, ovatoxin-g and the so far called putative palytoxin, whose structures had not been elucidated before. Insufficient quantity of these compounds impeded a full nuclear magnetic resonance (NMR)-based structural elucidation; thus, we studied their structure in crude algal extracts through liquid chromatography–electrospray ionization high-resolution mass spectrometry n (LC-ESI-HRMS n ) in positive ion mode. Under the used MS conditions, the molecules underwent fragmentation at many sites of their backbone and a large number of diagnostic fragment ions were identified. As a result, tentative structures were assigned to both ovatoxin-g and the putative palytoxin, the latter being identified as a palytoxin isomer and re-named as  isobaric palytoxin.