Ostreopsis siamensis Palytoxin

Dinofiagellates belonging to the genus Ostreopsis have been proposed as possible biogenetic origins of palytoxin (Usami et al. 1995 Taniyama et al. 2003). This theory is further supported because of the implication of Ostreopsis siamensis in a case of clupeotoxism where the causative agent was found to be palytoxin or one of its analogues (Onuma et al. 1999). 

Rhodes, L., Towers, N., Briggs, L., Munday, R., and Adamson, J. 2002. Uptake of palytoxin-like compounds by shellfish fed Ostreopsis siamensis (Dinophyceae). New Zealand Journal of Marine and Freshwater Research 36(3) 631-636. 

Ukena, T, Satake, M., Usami, M., Oshima, Y, Fujita, T, Kan, Y, and Yasumoto, T. 2001. Structure elucidation of ostreocin-D, a palytoxin analog isolated from the dinoflagellate Ostreopsis siamensis. Bioscience, Biotechnology and Biochemistry 65(ll) 2585-2588. 

Another zoanthid-derived polyketide that is likely produced by a dinoflagellate is palytoxin (125), an extremely potent neurotoxin from Palythoa toxica and several other unrelated animals. The closely related ostreocins, for example, ostreocin D (126), have been reported from a free-living dinoflagellate Ostreopsis siamensis, indicating a similar source in the animal. ... 

Yasumotto, T. et al., Palytoxin analogs from the dinoflagellate Ostreopsis siamensis, J. Am. Chem. Soc.,... 

This section will focus on the available chemical data concerning only toxic substances produced by Ostreopsis sp., shown to possess palytoxin characteristics. For reasons of convenience, toxins will be presented according to producing species. Palytoxin-like compounds have been reported for O. siamensis, O. ovata, and O. mascarenensis. The neurotoxins ostreotoxin-1 and -3 produced by O. lenticularis have not been to date characterised by use of analytical methods as palytoxin analogues, despite their reported mouse lethality and possible connection to ciguatera (Tindall et al. 1990 Mercado et al. 1994 Meunier et al. 1997). With regard to the last of the toxic species, the oidy... 

O. siamensis was first characterized as a toxin producer by Nakajima et al. (1981). Some years later, Yasumoto et al. (1987) and Holmes et al. (1988) reported the lethafity and haemolytic activity of the O. siamensis toxins. Usami et al. (1995) were the first to elucidate the structure of the major ostreocin produced by O. siamensis (strain SOA 1 from Aka island, Okinawa, Japan) and point out its structural and chemical properties resemblance to palytoxin. This major constituent was named ostreocin-D and accounted for 90% of total toxicity of extracts. None of the other (more than 10) minor ostreocins present in the O. siamensis extracts were identical to palytoxin, as initially indicated by ESl-MS (Ukena et al. 2001, 2002). New Zealand O. siamensis isolates have also been reported to produce toxins exhibiting strong haemolytic activity and mouse lethality (Rhodes et al. 2000, 2002). Recently, Penna et al. (2005) have reported the presence of toxins with strong delayed haemolytic activity in Ostreopsis cf siamensis from the NW Mediterranean Sea. This haemolytic activity was inhibited by the palytoxin antagonist ouabain, indicating the palytoxin-like nature of these toxins. 

Although some of the toxins produced from dinoflageUates belonging to the genus Ostreopsis (Dinophyceae) are named after the producing species, the term ostreocins is frequently used to describe such toxins. The palytoxin-like character of the major ostreocin from O. siamensis was first established by Usami et al. [23], indicating that this species could be one of the biogenetic sources of palytoxin. Since then, numerous researchers have reported the presence of palytoxin-like compounds in Ostreopsis spp. 

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