Metal Complexes and Free Radical Toxins Produced by Pfiesteria piscicida

Abstract

Metal-containing organic toxins produced by Pfiesteria piscicida were characterized, for the first time, by corroborating data obtained from five distinct instrumental methods: nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography particle beam glow discharge mass spectrometry (LC/PB-G DMS), electron paramagnetic resonance spectroscopy (EPR), and X-ray absorption spectroscopy (XAS). The high toxicity of the metal-containing toxins is due to metal-mediated free radical production. This mode of activity explains the toxicity of Pfiesteria, as well as previously reported difficulty in observing the molecular target, due to the ephemeral nature of radical species. The toxins are highly labile in purified form, maintaining activity for only 2-5 days before all activity is lost. The multiple toxin congeners in active extracts are also susceptible to decomposition in the presence of white light, pH variations, and prolonged heat. These findings represent the first formal isolation and characterization of a radical forming toxic organic-ligated metal complex isolated from estuarine/marine dinoflagellates. These findings add to an increased understanding regarding the active role of metals interacting with biological systems in the estuarine environment, as well as their links and implications to human health.

Identification of toxic fatty acid amides isolated from the harmful alga Prymnesium parvum carter

“…The IC 50 values of LHA are over 3 orders of magnitude lower for certain lipoxygenases than cycloxygenases (Butovich and Lukyanova, 2008). Metal containing organic toxins have also been characterized and reported in the dinoflagellate, Pfeisteria piscicida (Moeller et al, 2007). Divalent metals have been shown to be cofactors that increase the toxicity of P. parvum extracts (Yariv and Hestrin, 1961;Ulitzer and Shilo, 1966), and enhanced toxicity is observed in waters with high mineral content.…”

Mixotrophy, a major mode of nutrition for harmful algal species in eutrophic waters

“…Toxic strains Moeller et al, 2007) thrive in eutrophic estuaries Magnien et al, 2000;Glasgow et al, 2001); linked both directly (via nutrient uptake-experiments by Lewitus et al, 1999b;Glibert et al, 2006b) and indirectly to nutrient enrichment (experiments by Lewitus et al, 1999a;Burkholder et al, 2001a,b) +Phagotrophy (cryptophytes, other algae) while harboring cryptophyte kleptochloroplasts; +osmotrophy (urea)…”

Feeding by protists and copepods on the heterotrophic dinoflagellates Pfiesteria piscicida, Stoeckeria algicida, and Luciella masanensis

“…This suggests that chemicals excreted from L. masanensis may inhibit feeding by S. jeokjo. Recently, Moeller et al (2007) reported the nature of toxins produced by P. piscicida (i.e. metal complexes and free radical toxins) by using 5 different analytical methods.…”