FIRST EVIDENCE OF PALYTOXIN ANALOGUES FROM AN OSTREOPSIS MASCARENENSIS (DINOPHYCEAE) BENTHIC BLOOM IN SOUTHWESTERN INDIAN OCEAN¹

Abstract

Benthic dinoflagellates of the genus Ostreopsis Schmidt are common in tropical and subtropical water, and some species produce toxins potentially involved in human intoxication events. A benthic bloom of Ostreopsis mascarenensis Quod was observed near Rodrigues Island during a survey of benthic dinoflagellates in the southwestern Indian Ocean. The morphology of O. mascarenensis was studied by LM and SEM. Preliminary screening of a crude extract of an O. mascarenensis bloom revealed neurotoxicity in mice similar to that induced by palytoxin. After partition of the crude extract, the highest toxicity was retained in the butanol-soluble fraction, which retained hemolytic activity suggestive of palytoxin analogues. Two new toxins, mascarenotoxin-A and -B, were resolved from this fraction by HPLC coupled to a diode array detector. The closed mass spectrum profile and fragmentation pattern obtained by advanced nano-electrospray ionization quadrupole time-of-flight mass spectrometry between purified toxins and a reference palytoxin confirmed the mascarenotoxins as palytoxin analogues. These results were confirmed by tandem mass spectrometry with the identification of specific fragment ion m/z 327. An on-line liquid chromatography protocol coupled to tandem mass spectrometry was developed for detection of these palytoxin analogues. The present study describes the first purification, chemical, and toxicological characterization of new palytoxin analogues isolated from a benthic bloom of O. mascarenensis. These results suggest that O. mascarenensis, which is largely distributed in the southwestern Indian Ocean, could be a source of palytoxin poisoning in this tropical area.

High Resolution LC-MSn Fragmentation Pattern of Palytoxin as Template to Gain New Insights into Ovatoxin-a Structure. The Key Role of Calcium in MS Behavior of Palytoxins

“…Since natural extracts are usually contaminated by a complex mixture of palytoxin-like compounds (mascarenotoxins, ovatoxins, ostreocins, etc.) [10,17,18,21], this approach could also be used for a preliminary structural characterization of the unknown minor components contained in the extracts at levels too low for NMR studies.…”

Cambios estacionales en conjuntos de dinoflagelados epifíticos cerca de la costa norte de la Península de Yucatán, Golfo de México

“…Ostreopsis species are usually a common component of the epiphytic assemblage in tropical and subtropical waters (Bomber et al, 1985(Bomber et al, , 1988Carlson & Tindall, 1985;Gillespie et al, 1985;Ballantine et al, 1988;Quod, 1994;Faust, 1996Faust, , 2004Faust et al, 1996Faust et al, , 2005Tindall & Morton, 1998;Rhodes et al, 2000;Turquet et al, 2001;Lenoir et al, 2004;Shears & Ross, 2009;Kim et al, 2011), including the Mediterranean Sea (Tognetto et al, 1995;Vila et al, 2001;Aligizaki & Nikolaidis, 2006;Totti et al, 2010). This fact may be explained by the preference of Ostreopsis species for a particular substrate.…”

Ciguatera-Causing Dinoflagellates in a Coral-reef Mangrove Ecosystem, Belize

“…Cell surface is smooth and covered with randomly spaced small pores. The morphology of Ostreopsis species in scanning electron micrographs are illustrated in the following publications: O. ovata Fukuyo and O. lenticularis Fukuyo (1981) and ; O. heptagona Norris, Bomber et Balech (1985) and ; O. mascarenensis Quod (1994), , and Lenoir et al, (2004); O. labens Faust and Morton (1995); and O. siamensis Schmidt ; O. marinus Faust, O. belizeanus Faust, and O. caribbeanus Faust (1999 Meunier (1919). The type species in the genus is Coolia monotis Meunier.…”