Ostreopsis lenticularis

Mercado, J.A., Viera, M., Escalona de Motta, G., Tosteson, T.R., Gonzalez, L, and Silva, W. 1994. An extraction procedure modification changes the toxicity, chromatographic profile and pharmacologic action of Ostreopsis lenticularis extracts. Toxicon 32(3) 256. 

Meunier, F.A., Mercado, J.A., Molg6, J., Tosteson, T.R., and Escalona de Motta, G. 1997. Selective depolarization of the muscle membrane in frog nerve-muscle preparations by a chromatographically purified extract of the dinoflagellate Ostreopsis lenticularis. British Journal of Pharmacology 121(6) 1224 —1230. 

Tindall, D.R., Miller, DM., and Tindall, PM. 1990. Toxicity of Ostreopsis lenticularis from the British and United States Virgin Islands. In Toxic Marine Phytoplankton, ed. Graneli, E., Sundstrom, B., Edier, L., and Anderson, DM. New York Elsevier, pp. 424 - 429. 

Two rather interesting racemic syntheses for allylic methylated fatty acids have been recently accomplished [15]. One of these corresponds to the intriguing (12 )-11-methyl-12-octadecenoic acid (6), a marine bacterial fatty acid that in most reported identifications from natural sources has been shown to have the E double bond stereochemistry, but both Z,E isomers have been synthesized [15]. This mainly bacterial fatty acid was initially isolated from Byrsocarpus coccineus seed oil [16], but later it was reported in a bacterium associated with cat scratch disease [17], in Mycobacterium fallax [18], and most recently in a Pseudomonas sp. (.Alteromonas) associated with both the toxic dinoflagellate Ostreopsis lenticularis and several Caribbean Palythoa species [15]. More recently, acid 6 has been identified as an intermediate in the biosynthesis of the bacterial acid 10,13-epoxy-l l-methyloctadeca-10,12-dienoic acid, a furan fatty acid identified in several marine bacteria such as Shewanella putrefaciens [19-20]. 

It has been hypothesized that bacteria associated with toxic dinoflagellates act synergistically to synthesize toxins. Tosteson et al. (1986, 1989) examined the associated bacterial flora, growth and toxicity of cultured Ostreopsis lenticularis, and Ga. toxicus. Ga. toxicus clones were characterized by the presence of Pseudomonas spp. but extracts of dinoflagellate associated bacteria in pure culture were not toxic. Peak toxicity of O. lenticularis occurred during stationary phase and correlated with increases in bacterial biomass. 

Tosteson, T.R., Ballantine, D., Tosteson, C.G., Hensley, V. and Bardales, A.T. Associated bacterial flora, growth and toxieity of cultured beuthic dinoflagellates Ostreopsis lenticularis aud Gambierdiscus toxicus, Appl. Envir. Microbiol., 55, 137-141, 1989. 

Escalona de Motta, G., et al.. Modulation of acetylchohne receptor channel by a polar component isolated from toxic Ostreopsis lenticularis extracts. Bull. Soc. Path. Ex., 85, 489, 1992. 

Carballeira, N.M., Emiliano, A., Sostre, A., Restituyo, J.A., Gonzalez, 1. M., Colon, G.M., Tosteson, C.G., and Tosteson, T.R. (1998) Fatty acid composition of bacteria associated with the toxic dinofiagellate Ostreopsis lenticularis and with Caribbean Pcdythoa species. Lipids, 33, (,27-(,32. 

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... 

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