The harmful blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the coastlines of the Mediterranean Sea, since it 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 two Ostreopsis cf. ovata strains isolated from the south of Catalonia (NW Mediterranean Sea) in August, 2011. Our strains produced two novel compounds, ovatoxin-g and an isomer of palytoxin whose structures had not been elucidated yet. Although the quantity of these compounds was not sufficient for a full NMR-based structural elucidation, thus we studied their structure through Liquid Chromatography Electro Spray Ionization High Resolution Mass Spectrometry (LC-ESI-HRMS) in positive ion mode, following the LC-HRMSn approach developed by Ciminiello et al. 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. Their MSn spectra were investigated in light of the reported structure of ovatoxin-a and palytoxin from Palythoa tuberculosa (commercially available as analytical standard). As a result, ovatoxin-g was tentatively identified as 46-deoxy-ovatoxin-a, while the novel isomer of palytoxin would have two additional hydroxyl groups (one in the region C1 and C8 and one at C42) and two hydroxyl lacking (one at C17 and one in the region C53 and C79, compared to palytoxin standard. Ovatoxin-g and putative palytoxin were the least abundant palytoxin-like compounds (0.8% and 0.4% respectively) in a toxin profile dominated by ovatoxin-a (53%). Ovatoxin-b to –e (30%, 4%, 6%, 7% respectively) were also present, while production of ovatoxin-f was not observed. These strains are still under investigation to confirm the presence of other potentially new palytoxin congeners.
Novel ovatoxin-g and putative palytoxin from Ostreopsis cf. ovata (NW Mediterranean Sea): gaining structural information through high resolution mass spectrometry / Maria Garcia, Altares; Olga, Carnicier; Pablo de la, Iglesia; Jorge, Diogene; Ciminiello, Patrizia; Dell'Aversano, Carmela; Tartaglione, Luciana. - (2014), pp. 119-119. (Intervento presentato al convegno ICHA New Zealand 2014. The 16th International Conference on Harmful Algae tenutosi a Wellington, New Zealand nel 27-31 October 2014).
Novel ovatoxin-g and putative palytoxin from Ostreopsis cf. ovata (NW Mediterranean Sea): gaining structural information through high resolution mass spectrometry
CIMINIELLO, PATRIZIA;DELL'AVERSANO, CARMELA;TARTAGLIONE, LUCIANA
2014
Abstract
The harmful blooms of the benthic dinoflagellate Ostreopsis cf. ovata are a concern in the coastlines of the Mediterranean Sea, since it 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 two Ostreopsis cf. ovata strains isolated from the south of Catalonia (NW Mediterranean Sea) in August, 2011. Our strains produced two novel compounds, ovatoxin-g and an isomer of palytoxin whose structures had not been elucidated yet. Although the quantity of these compounds was not sufficient for a full NMR-based structural elucidation, thus we studied their structure through Liquid Chromatography Electro Spray Ionization High Resolution Mass Spectrometry (LC-ESI-HRMS) in positive ion mode, following the LC-HRMSn approach developed by Ciminiello et al. 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. Their MSn spectra were investigated in light of the reported structure of ovatoxin-a and palytoxin from Palythoa tuberculosa (commercially available as analytical standard). As a result, ovatoxin-g was tentatively identified as 46-deoxy-ovatoxin-a, while the novel isomer of palytoxin would have two additional hydroxyl groups (one in the region C1 and C8 and one at C42) and two hydroxyl lacking (one at C17 and one in the region C53 and C79, compared to palytoxin standard. Ovatoxin-g and putative palytoxin were the least abundant palytoxin-like compounds (0.8% and 0.4% respectively) in a toxin profile dominated by ovatoxin-a (53%). Ovatoxin-b to –e (30%, 4%, 6%, 7% respectively) were also present, while production of ovatoxin-f was not observed. These strains are still under investigation to confirm the presence of other potentially new palytoxin congeners.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
