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Palytoxin is a strong marine toxin that was first isolated from the zoantharian Palythoa toxica and later from other species of the genus Palythoa. How the toxin gets into the animal remains an unsolved question. To study the specificity of palytoxin distribution, the toxin content of Palythoa tuberculosa and other organisms living in close association on a coral reef in Okinawa were analysed by mass spectrometry. In contrast to earlier reports, palytoxin was only detected in P. tuberculosa colonies.

A series of case reports and anecdotal references describe the adverse effects on human health ascribed to the marine toxin palytoxin (PLTX) after different exposure routes. They include poisonings after oral intake of contaminated seafood, but also inhalation and cutaneous/systemic exposures after direct contact with aerosolized seawater during Ostreopsis blooms and/or through maintaining aquaria containing cnidarian zoanthids. The symptoms commonly recorded during PLTX intoxication are general malaise and weakness, associated with myalgia, respiratory effects, impairment of the neuromuscular apparatus and abnormalities in cardiac function. Systemic symptoms are often recorded together with local damages whose intensity varies according to the route and length of exposure. Gastrointestinal malaise or respiratory distress is common for oral and inhalational exposure, respectively. In addition, irritant properties of PLTX probably account for the inflammatory reactions typical of cutaneous and inhalational contact. Unfortunately, the toxin identification and/or quantification are often incomplete or missing and cases of poisoning are indirectly ascribed to PLTXs, according only to symptoms, anamnesis and environmental/epidemiological investigations (i.e. zoanthid handling or ingestion of particular seafood). Based on the available literature, we suggest a “case definition of PLTX poisonings” according to the main exposure routes, and, we propose the main symptoms to be checked, as well as, hemato-clinical analysis to be carried out. We also suggest the performance of specific analyses both on biological specimens of patients, as well as, on the contaminated materials responsible for the poisoning. A standardized protocol for data collection could provide a more rapid and reliable diagnosis of palytoxin-poisoning, but also the collection of necessary data for the risk assessment for this family of toxins.

A rapid, high resolution liquid chromatography coupled with ElectroSpray Ionization Time-Of-Flight Mass Spectrometry (ESI/TOF/MS) method was developed for the determination of the toxin pattern in cultured cells of Ostreopsis cf. ovata from the Mediterranean Sea. The samples were separated on a Phenomenex Luna 3μ HILIC 200A (150 × 2.00 mm) and analyzed by LC/TOF/MS with electrospray ionization (ESI) interface in positive ion mode. The method developed here provides the capability for a fully automated analysis, which requires relatively easy sample preparation and gives clean and simple chromatograms. The method was successfully applied to the determination of ovatoxin-a, mascarenotoxin-a and four new palytoxins in O. cf. ovata. Another new palytoxin was detected in the standard material from Palythoa tuberculosa provided by Wako Chemicals.

A very potent cell-bursting principle was isolated from the extract of the zoanthid Palythoa aff. margaritae. The compound was identified as palytoxin by comparing the spectral data and HPLC profile with those of an authentic sample.

A case of human poisoning by palytoxin after contact with zoanthid corals (Parazoanthus sp.) in an aquarium through skin injuries on fingers is reported. The clinical symptoms include swelling, paraesthesia and numbness around the site of the injury spreading over the arm, but also signs of systemic poisoning such as dizziness, general weakness and myalgia, irregularities in the ECG and indications of rhabdomyolysis. Symptomatic treatment consisted of infusion of physiological fluids. The patient recovered within 3 days. Analysis of the zoanthid coral involved revealed extremely high concentrations of palytoxin (between 2 and 3 mg/g).

Animals may acquire toxicity by absorbing toxic compounds from their food, e.g. from plants or other animals. Sequestration and accumulation of toxins may provide protection from predators, which learn to avoid this prey because of unpleasant experiences such as bitter taste. This is a common phenomenon in marine as well as in terrestrial ecosystems. Moreover, toxins may enter food chains where they accumulate reaching high, often lethal concentrations. Palytoxin which had been primarily detected in marine zoanthids (Palythoa sp.), occurs also in a wide range of other animals, e.g. in sponges, corals, shellfish, polychaetes and crustaceans, but also in fish, which feed on crustaceans and zoanthids as well. These animals exhibit a high resistance to the toxin's action. The mechanisms which protect the Na+, K+–ATPase of their cell membranes, the primary target of palytoxin, is unknown. Sequestration of the toxin by other animals may cause health problems due to food poisoning.

Palytoxin (PTX), a potent toxin isolated from the marine soft coral Palythoa tuberculosa increases the cationic permeability of red cell membranes and inhibits the (Na + ,K + )-activated ATPase, effects that are completely reversed by ouabain. It has also been shown to compete with ouabain for a binding site and it has been suggested that it binds to the Na + ,K + -pump molecule in cells. In a search for analogues of PTX that would bind covalently and could thus be used to identify and characterize the binding site, we have used compounds which differed from PTX at one end or at both ends simultaneously. In order to determine whether these derivatives could be used to replace palytoxin, we tested their potency to induce an increased cation flux, compete with ouabain for its binding site, and inhibit the isolated, purified (Na + ,K + -ATPase). The results obtained indicate that departures from the PTX structure at one end or at both ends simultaneously substantially decrease the ability of the compounds to increase the cationic permeability of red blood cells and to inhibit the (Na + ,K + -ATPase). These actions were found to be com- pletely reversed by ouabain, but the analogues are two to three orders of magnitude less potent that PTX in competing with ouabain for its binding site. These results suggest that both ends of the palytoxin molecule participate in the interactions of the toxin with its receptor and that modifications in these regions of the molecule produce significant alterations in its binding and subsequent action on red cell membranes.

L. Levine , H. Fujiki , H. B. Gjika and H. Van Vunakis . A radioimmunoassay for palytoxin. Toxicon26, 1115–1121, 1988.—Palytoxin, labelled with 125I-Bolton-Hunter reagent on its terminal amino group, bound specifically to rabbit anti-palytoxin. The extent of binding increased progressively with repeated immunizations. After absorption of the rabbit IgGs with a goat anti-rabbit IgG, binding was reduced greater than 95%. For 50% inhibition of binding in the 125I-palytoxin-anti-palytoxin reaction 0.27 pmoles of unlabelled palytoxin was required. Maitotoxin, teleocidin, okadaic acid, debromoaplysiatoxin and 12-O-tetradecanoylphorbol-13-acetate, when tested at 10–100-fold higher concentrations than palytoxin did not affect binding. Palytoxin's serologic activity was stable after 60 min exposure to 100°C and after 60 min exposure to 0.1 N HCl at 50°C, but its capacity to stimulate the arachidonic acid metabolism of rat liver cells was reduced after the 60 min exposure to 0.1 N HCl treatments at 35°C or 0.01 N HCl at 50°C. The average binding constant (K0) as determined by separation of antibody-bound palytoxin from free palytoxin by the double antibody technique was 4.9 × 109 M−1 at 0°C. This apparent average association constant increased with increasing temperature suggesting that palytoxin's epitope, most likely hydrophilic, is bound to H2O and the H2O is displaced before binding to the antibody's paratope.

Palytoxin (PTX) is a very potent marine toxin isolated from the Zoanthid Palythoa . Its effects on the nerve membrane have been studied on two different preparations: the giant axon of the Cockroach, Periplaneta americana and the giant axon of the Squids, Loligo pealei and Loligo forbesi . In both preparations, PTX at concentrations ranging from 0.03 to 10 μM depolarized the axonal membrane through a selective increase in the resting sodium conductance. This increase was never reversible and was only temporarily and partly antagonized by tetrodotoxin (TTX) at concentrations which block completely the voltage-dependent sodium conductance. A voltage-clamp analysis of these effects showed that, besides this increase, PTX induced complex modifications of the voltage-dependent ionic conductances and increased the leak conductance. The selectivity of the PTX induced sodium channels seemed to decrease with time. Altogether, the results indicate that PTX induces strong and irreversible modifications of the membrane structure.

Playtoxin, the toxin extracted from the soft coral Palythoa vestitus , Verril 1928, found in the Hawaiian and other Pacific Islands, is a highly lethal substance in several animal species, and is effective by various routes of administration. Its intravenous LD 50 in the dog, rabbit, monkey, guinea pig, rat, and mouse range between 0·033 and 0·45 μg/kg. However, when palytoxin is given by the intragastric or intrarectal route, it is relatively non-toxic. Additionally, playtoxin produces marked irritant and tissue damage when topically applied to skin or eyes, as well as having a general necrotizing action on cells when injected.

A. C. Alcala , L. C. Alcala , J. S. Garth , D. Yasumura and T. Yasumoto . Human fatality due to ingestion of the crab Demania reynaudii that contained a palytoxin-like toxin. Toxicon26, 105 –, 107, 1988.—Clinical accounts of a human fatality resulting from ingestion of the crab Demania reynaudii are documented. The causative toxin was suggested to be palytoxin on the basis of dose-death time relationships and chromatographic properties.