A case of palytoxin poisoning due to contact with zoanthid corals through a skin injury

The application and sustainable development of coral in traditional medicine and its chemical composition, pharmacology, toxicology, and clinical research

This review discusses the variety, chemical composition, pharmacological effects, toxicology, and clinical research of corals used in traditional medicine in the past two decades. At present, several types of medicinal coral resources are identified, which are used in 56 formulas such as traditional Chinese medicine, Tibetan medicine, Mongolian medicine, and Uyghur medicine. A total of 34 families and 99 genera of corals are involved in medical research, with the Alcyoniidae family and Sarcophyton genus being the main research objects. Based on the structural types of compounds and the families and genera of corals, this review summarizes the compounds primarily reported during the period, including terpenoids, steroids, nitrogen-containing compounds, and other terpenoids dominated by sesquiterpene and diterpenes. The biological activities of coral include cytotoxicity (antitumor and anticancer), anti-inflammatory, analgesic, antibacterial, antiviral, immunosuppressive, antioxidant, and neurological properties, and a detailed summary of the mechanisms underlying these activities or related targets is provided. Coral toxicity mostly occurs in the marine ornamental soft coral Zoanthidae family, with palytoxin as the main toxic compound. In addition, nonpeptide neurotoxins are extracted from aquatic corals. The compatibility of coral-related preparations did not show significant acute toxicity, but if used for a long time, it will still cause toxicity to the liver, kidneys, lungs, and other internal organs in a dose-dependent manner. In clinical applications, individual application of coral is often used as a substitute for orthopedic materials to treat diseases such as bone defects and bone hyperplasia. Second, coral is primarily available in the form of compound preparations, such as Ershiwuwei Shanhu pills and Shanhu Qishiwei pills, which are widely used in the treatment of neurological diseases such as migraine, primary headache, epilepsy, cerebral infarction, hypertension, and other cardiovascular and cerebrovascular diseases. It is undeniable that the effectiveness of coral research has exacerbated the endangered status of corals. Therefore, there should be no distinction between the advantages and disadvantages of listed endangered species, and it is imperative to completely prohibit their use and provide equal protection to help them recover to their normal numbers. This article can provide some reference for research on coral chemical composition, biological activity, chemical ecology, and the discovery of marine drug lead compounds. At the same time, it calls for people to protect endangered corals from the perspectives of prohibition, substitution, and synthesis.

The structure of the neurotoxin palytoxin determined by MicroED

Palytoxin (PTX) is a potent neurotoxin found in marine animals that can cause serious symptoms such as muscle contractions, haemolysis of red blood cells and potassium leakage. Despite years of research, very little is known about the mechanism of PTX. However, recent advances in the field of cryoEM, specifically the use of microcrystal electron diffraction (MicroED), have allowed us to determine the structure of PTX. It was discovered that PTX folds into a hairpin motif and is able to bind to the extracellular gate of Na,K-ATPase, which is responsible for maintaining the electrochemical gradient across the plasma membrane. These findings, along with molecular docking simulations, have provided important insights into the mechanism of PTX and can potentially aid in the development of molecular agents for treating cases of PTX exposure.

First Characterization of Ostreopsis cf. ovata (Dinophyceae) and Detection of Ovatoxins during a Multispecific and Toxic Ostreopsis Bloom on French Atlantic Coast

Blooms of the benthic toxic dinoflagellate genus Ostreopsis have been recorded more frequently during the last two decades, particularly in warm temperate areas such as the Mediterranean Sea. The proliferation of Ostreopsis species may cause deleterious effects on ecosystems and can impact human health through skin contact or aerosol inhalation. In the eastern Atlantic Ocean, the toxic O. cf. ovata has not yet been reported to the north of Portugal, and the only species present further north was O. cf. siamensis, for which the toxic risk is considered low. During summer blooms of unidentified Ostreopsis species on the French Basque coast (Atlantic) in 2020 and 2021, people suffered from irritations and respiratory disorders, and the number of analyzed cases reached 674 in 2021. In order to investigate the causes, sampling was carried out during summer 2021 to (i) taxonomically identify Ostreopsis species present using a molecular approach, (ii) isolate strains from the bloom and culture them, and (iii) characterize the presence of known toxins which may be involved. For the first time, this study reports the presence of both O. cf. siamensis and O. cf. ovata, for which the French Basque coast is a new upper distribution limit. Furthermore, the presence of ovatoxins a, b, c, and d in the environmental sample and in a cultivated strain in culture confirmed the toxic nature of the bloom and allowed identifying O. cf. ovata as the producer. The present data identify a new health risk in the area and highlight the extended distribution of some harmful dinoflagellates, presumably in relation to climate change.

Coral Keratitis: Case Report and Review of Mechanisms of Action, Clinical Management and Prognosis of Ocular Exposure to Palytoxin

Palytoxin is one of the most lethal natural toxins ever discovered. This molecule has been isolated from various marine animals, including zoanthid corals. This popular organism is commonly found in many home saltwater aquariums due to its beauty and survivability. As a result of an increase in popularity, an increased number of individuals are at risk for exposure to this potentially deadly toxin. Affected patients may experience various symptoms based on the route of exposure (ie, cutaneous contact, inhalation of aerosolized toxin, ocular exposure, or ingestion). Ocular exposure can occur in various ways (eg, contact with contaminated water, rubbing the eye with a dirtied hand, or direct spraying into the eye), and incidence rates have dramatically risen in recent years. In this review, we discuss a case of systemic toxicity from inhalation and ocular exposure to presumed palytoxin on a zoanthid coral which resulted in an intensive care unit (ICU) stay, and corneal perforation which required a corneal transplant. Additionally, we review what is known about the mechanism of action of this toxin, propose a comprehensive hypothesis of its effects on corneal cells, and discuss the prognosis and clinical management of patients with systemic symptoms secondary to other routes of exposure.

In Vivo Evaluation of the Chronic Oral Toxicity of the Marine Toxin Palytoxin

Palytoxin (PLTX) is one of the most poisonous substances known to date and considered as an emergent toxin in Europe. Palytoxin binds to the Na⁺-K⁺ ATPase, converting the enzyme in a permeant cation channel. This toxin is known for causing human fatal intoxications associated with the consumption of contaminated fish and crustaceans such as crabs, groupers, mackerel, and parrotfish. Human intoxications by PLTX after consumption of contaminated fishery products are a serious health issue and can be fatal. Different reports have previously explored the acute oral toxicity of PLTX in mice. Although the presence of palytoxin in marine products is currently not regulated in Europe, the European Food Safety Authority expressed its opinion on PLTX and demanded assessment for chronic toxicity studies of this potent marine toxin. In this study, the chronic toxicity of palytoxin was evaluated after oral administration to mice by gavage during a 28-day period. After chronic exposure of mice to the toxin, a lethal dose 50 (LD₅₀) of 0.44 µg/kg of PLTX and a No-Observed-Adverse-Effect Level (NOAEL) of 0.03 µg/kg for repeated daily oral administration of PLTX were determined. These results indicate a much higher chronic toxicity of PLTX and a lower NOAEL than that previously described in shorter treatment periods, pointing out the need to further reevaluate the levels of this compound in marine products.

Paralytic shellfish poisoning and palytoxin poisoning in dogs

BACKGROUND

Fatal cases of exposure to paralytic shellfish toxins and palytoxins have occurred in companion animals but are poorly described.

METHODS

We describe one case of paralytic shellfish poisoning (PSP) and three cases of palytoxin poisoning in dogs.

RESULTS

Mild PSP occurred following ingestion of crab while walking on a beach. Analysis confirmed the presence of paralytic shellfish toxins, particularly decarbamoyl saxitoxin, in clinical samples and marine organisms. This case occurred shortly after an outbreak of PSP in dogs on the eastern coast of England. Palytoxin poisoning occurred in a dog after it chewed coral removed from an aquarium. Signs included collapse, hypothermia, bloody diarrhoea and respiratory distress. The dog was euthanised due to rapid deterioration and poor prognosis. Palytoxin was not detected in a premortem blood sample. Two other dogs in a separate incident developed only mild signs (fever and respiratory distress) after suspected exposure to aerosolised palytoxin and recovered within a few hours.

CONCLUSION

Cases of PSP are episodic and not common in dogs. Cases of palytoxin exposure are reportedly increasing in humans, and there is presumably also an increased risk to pets. There is no specific treatment for PSP or palytoxin poisoning.

Reevaluation of the acute toxicity of palytoxin in mice: Determination of lethal dose 50 (LD50) and No-observed-adverse-effect level (NOAEL)

Palytoxin is an emergent toxin in Europe and one of the most toxic substances know to date. The toxin disrupts the physiological functioning of the Na⁺/K⁺-ATPase converting the enzyme in a permeant cation channel. Human intoxications by PLTX after consumption of contaminated fishery products are a serious health issue and can be fatal. Several reports have previously investigated the oral and intraperitoneal toxicity of PLTX in mice. However, in all cases short observation periods (24 and 48 h) after toxin administration were evaluated. In this work, single oral or intraperitoneal doses of PLTX were administered to healthy mice and surviving animals were followed up for 96 h. The data obtained here allowed us to calculate the oral and intraperitoneal lethal doses 50 (LD₅₀) which were in the range of the values previously described. Surprisingly, the oral NOAEL for PLTX was more than 10 times lower than that previously described, a fact that indicates the need for the reevaluation of the levels of the toxin in edible fishery products.

Marine natural products from zoantharians: bioactivity, biosynthesis, systematics, and ecological roles

The dazzling marine zoantharians represent a reservoir of chemical diversity that remains to be unveiled. These fragile animals have so far been found to harbour the highly bioactive palytoxins or zoanthamines but also the harmless ecdysteroids or zoanthozanthins.

Inhalation poisoning with palytoxin from aquarium coral: case description and safety advice

Palythoa spp. corals and some other marine organisms contain one of the most poisonous substances ever known - palytoxin (PTX). Due to their modest life requirements and ease of breeding, these corals are popular in home aquariums. Here we refer to a case of PTX poisoning of a middle-aged woman who inhaled poisonous vapours while brushing the corals from live rock and compare it with the available literature. As the case revealed that the symptoms of PTX poisoning are not specific and neither is treatment, our aim was to give a brief tabulated review of the symptoms that may indicate such poisoning. Cases of palytoxin poisoning have been reported worldwide, and severe ones (mostly due to ingestion of contaminated sea food) can end in death. As it appears, most (if not all) poisonings result from unawareness of the risk and reckless handling by aquarists. This is one of the first articles which provides some practical advice about the use of personal protection equipment, including gloves, masks, eyewear, and other clothing during any coral manipulation to minimise the risk. We also draw attention to the lack of marketing/trading regulations for dangerous coral species and/or regulations or instructions dealing with their removal and health protection.

Toxicity of crude organic extracts from the zoanthid Palythoa caribaeorum: A biogeography approach

Marine isolates such as palytoxin (PTX) are of concern within the Caribbean region due to their toxicity. PTX for example has been described as a one of the most known potent marine toxins, known to prevent predation from larger species (e.g. vertebrates) as well as the prevention of being overgrown from other coral species. PTX is a polyhydroxylated polyether toxin with a very large and complex chemical structure that possesses both hydrophilic and lipophilic properties. Previous acute toxicity tests using brine shrimp (Artemia salina) and PTX extract had shown it to be moderately toxic. In humans, PTX has been credited to be responsible for extreme symptoms such anaphylactic shock, rapid cardiac failure and eventual death occurring within minutes. Extrapolation for human dose ranges has therefore been suggested to be between 2.3 and 31.5 μg. This study isolates a potentially PTX-enriched extract from Palythoa caribaeorum and examines its organic extract toxicity from a biogeography perspective from a within-colony to a variety of reef sites around Trinidad and Tobago that are popular for marine visitors. This research represents an acute study with a high level of crude organic extract toxicity on A. salina whilst postulating potential factors which may contribute to its extreme toxicity and the risk posed to users of these environments.

Anti-Lymphangiogenesis Components from Zoanthid Palythoa tuberculosa

Three new compounds, tuberazines A–C (1–3), and eleven known compounds (4–14) were obtained from the ethanolic extract of Taiwanese zoanthid Palythoa tuberculosa. Compounds 1–4 are rare marine natural products with a pyrazine moiety, and compound 5 is a tricyclic tryptamine derivative isolated from nature for the first time. The structures of all isolated metabolites were determined by analyzing their IR, Mass, NMR, and UV spectrometric data. The absolute configuration of 1 was confirmed by comparing the trend of experimental electronic circular dichroism (ECD) with calculated ECD spectra. The anti-lymphangiogenic activities of new compounds were evaluated in human lymphatic endothelial cells (LECs). Of these, new compound 3 displayed the most potent anti-lymphangiogenesis property by suppressing cell growth and tube formation of LECs.

Prevalence and characteristics of inhalational and dermal palytoxin exposures reported to the National Poison Data System in the U.S

INTRODUCTION

Palytoxin, produced by unicellular microalgae, is one of the most potent toxins known. Human exposure results most prominently through oral, dermal, and inhalational contact. There is no current data on the prevalence of cases in the United States.

METHODS

This study reviewed human inhalational and dermal exposures to palytoxin via records from the National Poison Data System from 2000 to 2014.

RESULTS

There were 171 cases reported, the majority occurred at a residence and experienced minor respiratory or dermal symptoms and recovered without any major sequelae or fatalities. Ten patients required admission to an intensive care unit.

CONCLUSION

The incidence of palytoxin exposure is low but significant symptoms can occur.

First Identification of Palytoxin-Like Molecules in the Atlantic Coral Species Palythoa canariensis

Palytoxin (PLTX) is a complex marine toxin produced by Zoanthids (Palyhtoa), dinoflagellates (Ostreopsis), and cyanobacteria (Trichodesmium). Contact with PLTX-like compounds present in aerosols or marine organisms has been associated with adverse effects on humans. The worldwide distribution of producer species and seafood contaminated with PLTX-like molecules illustrates the global threat to human health. The identification of species capable of palytoxin production is critical for human safety. We studied the presence of PLTX analogues in Palythoa canariensis, a coral species collected in the Atlantic Ocean never described as a PLTX-producer before. Two methodologies were used for the detection of these toxins: a microsphere-based immunoassay that offered an estimation of the content of PLTX-like molecules in a Palythoa canariensis extract and an ultrahigh-pressure liquid chromatography coupled to an ion trap with a time-of-flight mass spectrometer (UPLC-IT-TOF-MS) that allowed the characterization of the toxin profile. The results demonstrated the presence of PLTX, hydroxy-PLTX and, at least, two additional compounds with PLTX-like profile in the Palythoa canariensis sample. The PLTX content was estimated in 0.27 mg/g of lyophilized coral using UPLC-IT-TOF-MS. Therefore, this work demonstrates that Palythoa canariensis produces a mixture of PLTX-like molecules. This is of special relevance to safeguard human health considering Palythoa species are commonly used for decoration by aquarium hobbyists.

Genetic and toxinological characterization of North Atlantic strains of the dinoflagellate Ostreopsis and allelopathic interactions with toxic and non-toxic species from the genera Prorocentrum, Coolia and Gambierdiscus

The genus Ostreopsis includes several toxic species that can develop blooms in benthic ecosystems, with potential harmful consequences for human health and marine invertebrates. Despite of this, little is known about the allelopathic interactions between these organisms and other co-occurring microalgae that exploit similar spatial and nutrient resources in benthic ecosystems. The aim of this study was to follow these interactions in cultures of two Ostreopsis ribotypes with different toxin profiles (O. cf. ovata contained ovatoxins-a, b, c and e, while only ovatoxin-d was found in O .sp. "Lanzarote-type"), mixed with species of three benthic dinoflagellate genera (Coolia, Prorocentrum and Gambierdiscus), isolated from the same area (North East Atlantic, Canary Islands). In a first experiment, the potential allelopathic effects on growth rates were followed, in mixed cultures of Coolia monotis (a non toxic species) exposed to the clarified medium and to cells of O. sp."Lanzarote-type" and O. cf. ovata. Growth delayed in C. monotis was observed specially in clarified medium, while the O. sp. "Lanzarote-type" strain attained much lower densities in mixed cultures. In a second experiment, we examined the potential effects of clarified media from O. sp."Lanzarote-type" and O. cf. ovata on the adherence capacity in two toxic species (Prorocentrum hoffmannianum and Gambierdiscus excentricus). Contrasting effects were found: a significant increase of adherence capacity in P. hoffmannianum vs attachment decline in G. excentricus, that experienced also severe deleterious effects (cell lysis). Our results suggest the existence of weak to moderate allelopathic interactions between the studied organisms, although the outcome is dependent on the species involved.

Pro-inflammatory effects of palytoxin: an in vitro study on human keratinocytes and inflammatory cells

Palytoxin (PLTX) is one of the most harmful marine toxins known so far. Although the ingestion of contaminated seafood is the most dangerous exposure route for humans, cutaneous and inhalational exposures are far more frequent, and can cause strong inflammatory reactions. However, little is known about the inflammatory events that follow the cutaneous exposure to the toxin. In this study, we investigated (1) the effects of both short (2 h) and long (24 h) term exposures of HaCaT keratinocytes to a sub-cytotoxic PLTX concentration on pro-inflammatory mediator gene expression and release and (2) the effect of PLTX-conditioned HaCaT cell media on undifferentiated (monocytes) and differentiated (macrophages; immature dendritic cells, iDCs; mature dendritic cells, mDCs) THP-1 cells. At 10-11 M, PLTX induced interleukin (IL)-6 and IL-8 release from HaCaT keratinocytes after 24 h of continuous exposure to the toxin, as well as after 23 h in toxin-free medium preceded by 1 h exposure to PLTX. Under the same experimental conditions, release of the inflammatory mediators prostaglandin-E2 and histamine was also found after both short and long exposures to the toxin. The conditioned media collected from HaCaT cells treated with PLTX increased the migration of the differentiated and undifferentiated THP-1 cells (potency rank order: monocytes ≥ iDCs > mDCs > macrophages) but did not induce cell differentiation. These results indicate that keratinocytes can be actively involved in the recruitment of inflammatory cells in response to cutaneous contact with PLTX. The lack of a significant effect on monocyte differentiation towards mature immune cells suggests that PLTX is endowed with irritant rather than sensitizing properties.

Palytoxin-Containing Aquarium Soft Corals as an Emerging Sanitary Problem

Palytoxin (PLTX), one the most potent marine toxins, and/or its analogs, have been identified in different marine organisms, such as Palythoa soft corals, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria. Although the main concern for human health is PLTXs entrance in the human food chain, there is growing evidence of adverse effects associated with inhalational, cutaneous, and/or ocular exposure to aquarium soft corals contaminated by PLTXs or aquaria waters. Indeed, the number of case reports describing human poisonings after handling these cnidarians is continuously increasing. In general, the signs and symptoms involve mainly the respiratory (rhinorrhea and coughing), skeletomuscular (myalgia, weakness, spasms), cardiovascular (electrocardiogram alterations), gastrointestinal (nausea), and nervous (paresthesia, ataxia, tremors) systems or apparates. The widespread phenomenon, the entity of the signs and symptoms of poisoning and the lack of control in the trade of corals as aquaria decorative elements led to consider these poisonings an emerging sanitary problem. This review summarizes literature data on human poisonings due to, or ascribed to, PLTX-containing soft corals, focusing on the different PLTX congeners identified in these organisms and their toxic potential.

Determination of Palytoxins in Soft Coral and Seawater from a Home Aquarium. Comparison between Palythoa- and Ostreopsis-Related Inhalatory Poisonings

Anecdotal reports exist of aquarium hobbyists that experienced severe respiratory distress and/or skin injury following cleaning operation of home aquaria containing Palythoa sp. soft corals. Hundreds of cases of respiratory illness and/or dermatitis have been recorded in proximity to the sea concomitantly with algal blooms of Ostreopsis spp. in the Mediterranean area. Both Palythoa spp. and Ostreopsis spp. contain congeners of palytoxin, a highly potent toxin whose inhalation hazard is however unknown. In this study, we demonstrate the presence of high levels of palytoxins (palytoxin and hydroxypalytoxin) in both soft coral and seawater from a home marine aquarium involved in the poisoning of a whole family. Due to the high toxin levels found in seawater, a procedure for a rapid and efficient determination of palytoxin in seawater was setup. A comparison of symptoms of Palythoa- and Ostreopsis-related inhalatory poisonings showed many similarities including fever, respiratory distress, nausea, and flu-like symptoms. From the chemical and symptomatological data reported herein it is reasonable to hold palytoxins responsible for respiratory disorders following inhalation. Although the exact mechanism through which palytoxin congeners exert their inhalatory toxicity is still unknown, this represents a step toward demonstrating that palytoxin congeners exert toxic effects through inhalation both in natural environments and in the surroundings of private and public aquaria.

A Case of Palytoxin Poisoning in a Home Aquarium Enthusiast and His Family

Inhalational exposure to palytoxin is an extremely rare cause of respiratory distress. This little-known marine toxin has the potential to cause significant morbidity and mortality. Toxicity has been best documented in cases of ingestion but has also been seen in cases of dermal exposure and inhalation of vapors. Palytoxin has been found in several coral species, some of which are favored by home aquarium enthusiasts and are commercially available. We report a case of a family who were exposed to the aerosolized toxin following the cleaning of a coral in their home aquarium. It is important that clinicians be aware of this source of toxic exposure to provide necessary care to these patients.

Systemic toxic effects induced by the aqueous extract of the fire coral Millepora complanata and partial purification of thermostable neurotoxins with lethal effects in mice

Millepora complanata is a cnidarian widely distributed in the coral reefs of the Mexican Caribbean. This species is popularly known as "fire coral", since contact with it causes severe pain, skin eruptions and blisters. Intravenous administration of of M. complanata aqueous extract induces violent convulsions and death in mice within 1 min (LD50=4.62µgprotein/g of body weight). Doses less than the LD50 produced histopathological damage in kidneys and lungs. Such histopathological damage was completely eliminated after incubation of the extract in heat denaturing conditions. Unexpectedly, the denatured extract conserved its lethal effect. These findings demonstrated that the extract contained hemolytic and phospholipase activities that might be responsible for the histopathological damage, and additionally it contained other unidentified thermostable toxins with lethal effects in mice. Chromatographic analysis of the extract led to the isolation of a 61 kDa vasoconstrictor protein. Furthermore, several non-peptidic vasoconstrictor fractions were separated. Particularly interesting was the fraction MC1-IIA obtained as a result of three-step chromatography processes (ion exchange, gel filtration and reverse phase). Like the original crude extract, this fraction induced vasoconstriction and delayed hemolysis and lethal effects in mice. A subsequent chromatographic analysis of MC1-IIA showed that this fraction contained at least four non-peptidic compounds. MS and NMR spectroscopic data analyses indicated that these metabolites were poly-oxygenated alkylbenzenes. The present study constitutes the first report of the presence of non-peptidic lethal toxins in an organism of the class Hydrozoa, and evidences the great structural diversity of the toxins produced by the Millepora species.

The marine toxin palytoxin induces necrotic death in HaCaT cells through a rapid mitochondrial damage

Palytoxin (PLTX) is one of the most toxic algal biotoxin known so far. It transforms the Na(+)/K(+)-ATPase into a cationic channel inducing a massive intracellular Na(+) influx. However, from a mechanistic point of view, the features and the intracellular pathways leading to PLTX-induced cell death are still not completely characterized. This study on skin HaCaT keratinocytes demonstrates that PLTX induces necrosis since propidium iodide uptake was observed already after 1 h toxin exposure, an effect that was not lowered by toxin removal. Furthermore, necrotic-like morphological alterations were evidenced by confocal microscopy. Apoptosis occurrence was excluded since no caspases 3/7, caspase 8, and caspase 9 activation as well as no apoptotic bodies formation were recorded. Necrosis was preceded by a very early mitochondrial damage as indicated by JC-1 fluorescence shift, recorded already after 5 min toxin exposure. This shift was totally abolished when Na(+) and Ca(2+) ions were withdrawn from culture medium, whereas cyclosporine-A was ineffective, excluding the occurrence of a controlled biochemical response. These results clearly establish necrosis as the primary mechanism for PLTX-induced cell death in HaCaT cells. The rapidity of mitochondrial damage and the consequent irreversible necrosis rise serious concerns about the very fast onset of PLTX toxic effects.

Case series: inhaled coral vapor--toxicity in a tank

INTRODUCTION

Palytoxin (PTX) is considered a severe marine toxin. Although rare, reports of human exposure from consumption of PTX have described significant morbidity and mortality. PTX is the suspected agent in Haff disease, in which rhabdomyolysis occurs within 24 h of eating contaminated fish such as buffalo fish. PTX is primarily present in soft corals or in dinoflagellates, and it can contaminate crustaceans and other fish as it bioaccumulates up the food chain. Only 23 cases have been reported in the USA, including two recent cases in New York City. Reports of inhalational exposure to PTX are uncommon.

CASE REPORTS

We describe a case series of six patients, including four adults and two children, with inhalational exposure to PTX aerosolized from Palythoa corals. Their symptoms included some degree of respiratory involvement, myalgias, paresthesias, low-grade fevers, and gastrointestinal symptoms. Fortunately, there were no serious outcomes and all patients survived without sequelae.

DISCUSSION

Although rare, exposure to palytoxin is not restricted to people visiting marine environments because of Palythoa coral in some home aquariums. Routes of exposure go beyond consumption of fish that feed on the coral and include dermal as well as inhalational exposure. Palytoxin exposure should be considered in the differential diagnosis of patients who own or work with fish tanks and present with symptoms that include respiratory complaints, myalgias, neuromuscular dysfunction, hemolysis, and cardiac toxicity. There is no known antidotal therapy and treatment should focus on meticulous supportive care.

Cytotoxic and cytolytic cnidarian venoms. A review on health implications and possible therapeutic applications

The toxicity of Cnidaria is a subject of concern for its influence on human activities and public health. During the last decades, the mechanisms of cell injury caused by cnidarian venoms have been studied utilizing extracts from several Cnidaria that have been tested in order to evaluate some fundamental parameters, such as the activity on cell survival, functioning and metabolism, and to improve the knowledge about the mechanisms of action of these compounds. In agreement with the modern tendency aimed to avoid the utilization of living animals in the experiments and to substitute them with in vitro systems, established cell lines or primary cultures have been employed to test cnidarian extracts or derivatives. Several cnidarian venoms have been found to have cytotoxic properties and have been also shown to cause hemolytic effects. Some studied substances have been shown to affect tumour cells and microorganisms, so making cnidarian extracts particularly interesting for their possible therapeutic employment. The review aims to emphasize the up-to-date knowledge about this subject taking in consideration the importance of such venoms in human pathology, the health implications and the possible therapeutic application of these natural compounds.

Ovatoxin-a and palytoxin accumulation in seafood in relation to Ostreopsis cf. ovata blooms on the French Mediterranean coast

Dinoflagellates of the genus Ostreopsis are known to cause (often fatal) food poisoning in tropical coastal areas following the accumulation of palytoxin (PLTX) and/or its analogues (PLTX group) in crabs, sea urchins or fish. Ostreopsis spp. occurrence is presently increasing in the northern to north western Mediterranean Sea (Italy, Spain, Greece and France), probably in response to climate change. In France, Ostreopsis. cf. ovata has been associated with toxic events during summer 2006, at Morgiret, off the coast of Marseille, and a specific monitoring has been designed and implemented since 2007. Results from 2008 and 2009 showed that there is a real danger of human poisoning, as these demonstrated bioaccumulation of the PLTX group (PLTX and ovatoxin-a) in both filter-feeding bivalve molluscs (mussels) and herbivorous echinoderms (sea urchins). The total content accumulated in urchins reached 450 µg PLTX eq/kg total flesh (summer 2008). In mussels, the maximum was 230 µg eq PLTX/kg (summer 2009) compared with a maximum of 360 µg found in sea urchins during the same period at the same site. This publication brings together scientific knowledge obtained about the summer development of Ostreopsis spp. in France during 2007, 2008 and 2009.

Palytoxin found in Palythoa sp. zoanthids (Anthozoa, Hexacorallia) sold in the home aquarium trade

Zoanthids (Anthozoa, Hexacorallia) are colonial anemones that contain one of the deadliest toxins ever discovered, palytoxin (LD(50) in mice 300 ng/kg), but it is generally believed that highly toxic species are not sold in the home aquarium trade. We previously showed that an unintentionally introduced zoanthid in a home aquarium contained high concentrations of palytoxin and was likely responsible for a severe respiratory reaction when an individual attempted to eliminate the contaminant colonies using boiling water. To assess the availability and potential exposure of palytoxin to marine aquarium hobbyists, we analyzed zoanthid samples collected from local aquarium stores for palytoxin using liquid chromatography and high resolution mass spectrometry and attempted to identify the specimens through genetic analysis of 16S and cytochrome c oxidase 1 (COI) markers. We found four specimens of the same apparent species of zoanthid, that we described previously to be responsible for a severe respiratory reaction in a home aquarium, to be available in three aquarium stores in the Washington D.C. area. We found all of these specimens (n = 4) to be highly toxic with palytoxin or palytoxin-like compounds (range 0.5-3.5 mg crude toxin/g zoanthid). One of the most potent non-protein compounds ever discovered is present in dangerous quantities in a select species of zoanthid commonly sold in the home aquarium trade.

Case definitions for human poisonings postulated to palytoxins exposure

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.

Occurrence of palytoxin-group toxins in seafood and future strategies to complement the present state of the art

Palytoxin (PlTX) and palytoxin-like (PlTX-like) compounds in seafood have been raising scientific concern in the last years. The constant increase in record numbers of the causative dinoflagellates of the genus Ostreopsis together with the large spatial expansion of this genus has led to intensification of research towards optimization of methods for determination of PlTX presence and toxicity. In this context, identification of seafood species which could possibly contain PlTXs constitutes an important issue for public health protection. In the present paper, worldwide occurrence of PlTX-like compounds in seafood is reviewed, while potential future strategies are discussed. PlTX has been reported to be present in several species of fish, crustaceans, molluscs and echinoderms. In one occasion, PlTX has been identified in freshwater puffer fish whereas all other records of PlTXs refer to marine species and have been recorded in latitudes approximately between 43°N and 15°S. PlTX determination in seafood has relied on different methodologies (mainly LC-MS, mouse bioassay and hemolysis neutralization assay) that have evolved over time. Future recommendations include systematic screening of PlTX in those species and areas where PlTX has already been recorded implementing updated methodologies.

LC-MS of palytoxin and its analogues: State of the art and future perspectives

The state of the art of LC-MS of palytoxin and its analogues is reported in the present review. MS data for palytoxin, 42-hydroxy-palytoxin, ostreocin-D, mascarenotoxins, and ovatoxins, obtained using different ionization techniques, namely fast-atom bombardment (FAB), matrix assisted laser desorption ionization (MALDI), and electrospray ionization (ESI), are summarized together with the LC-MS methods used for their detection. Application of the developed LC-MS methods to both plankton and seafood analysis is also reported, paying attention to the extraction procedures used and to limits of detection (LOD) and quantitation (LOQ) achieved. In a research setting, LC-MS has shown a good potential in determination of palytoxin and its analogues from various sources, but, in a regulatory setting, routine LC-MS analysis of palytoxins is still at a preliminary stage. The LOQ currently achieved in seafood analysis appears insufficient to detect palytoxins in shellfish extract at levels close to the tolerance limit for palytoxins (30 μg/kg) proposed by the European Food Safety Authority (EFSA, 2009). In addition, lacking of certified reference standard of palytoxins as well as of validation studies for the proposed LC-MS methods represent important issues that should be faced for future perspectives of LC-MS technique.

Using hydrofluoric acid for morphological investigations of Zoanthids (Cnidaria: Anthozoa): a critical assessment of methodology and necessity

Zoanthids comprise an order of benthic, generally colonial cnidarians, which can usually be distinguished from other hexacorallians by embedded sand and detritus in their mesoglea to help strengthen their structure. These animals are becoming increasingly important research subjects in biochemistry and other research fields. Their inclusion of both calcium and silica results in the need for both decalcification and desilification for internal morphological examinations. Since the methodology of hydrofluoric acid (HF) desilification has rarely been documented in zoanthids, histological surveys for zoanthid taxonomy have often been abandoned and their taxonomy is often problematic. Recent investigations utilizing molecular methods have brought a clearer understanding of zoanthid diversity, but standardization of HF treatments are still needed to provide a link between molecular and more traditional techniques, and to properly examine specimens for which molecular methods may not be an option (e.g., formalin-preserved specimens, etc.). Here, we use both "straight" HF and, for the first time with zoanthids, buffered HF (BHF) treatments at different treatment lengths (1-48 h) on polyps from three different species of zoanthids for histological examination. Section conditions were judged based on the presence/absence of embedded detritus, drag marks, and tissue condition. Results show that the BHF treatment resulted in slightly better tissue conditions for all specimens, and suggest that desilification works well regardless of treatment time for species with smaller (polyp diameter <0.5 cm), less heavily encrusted polyps. Desilification of heavily encrusted Palythoa mutuki polyps were still problematic, with at least 24 h treatment needed. To aid future research, we provide guidelines for HF treatments of zoanthid specimens.

Palytoxin and analogs: biological and ecological effects

Palytoxin (PTX) is a potent marine toxin that was originally found in soft corals from tropical areas of the Pacific Ocean. Soon after, its occurrence was observed in numerous other marine organisms from the same ecological region. More recently, several analogs of PTX were discovered, remarkably all from species of the dinoflagellate genus Ostreopsis. Since these dinoflagellates are also found in other tropical and even in temperate regions, the formerly unsuspected broad distribution of these toxins was revealed. Toxicological studies with these compounds shows repeatedly low LD50 values in different mammals, revealing an acute toxic effect on several organs, as demonstrated by different routes of exposure. Bioassays tested for some marine invertebrates and evidences from environmental populations exposed to the toxins also give indications of the high impact that these compounds may have on natural food webs. The recognition of its wide distribution coupled with the poisoning effects that these toxins can have on animals and especially on humans have concerned the scientific community. In this paper, we review the current knowledge on the effects of PTX and its analogs on different organisms, exposing the impact that these toxins may have in coastal ecosystems.

Rapid isolation of single-chain antibodies by phage display technology directed against one of the most potent marine toxins: Palytoxin

Several recombinant antibodies against one of the most potent marine toxins, Palytoxin (PlTX), were obtained using two naive human semi-synthetic phage display libraries (Tomlinson I and J) as an effective method for generating specific anti-toxin single-chain variable fragment (scFv) antibodies. After four rounds of panning and selection on free palytoxin adsorbed immunotubes, individual clones were isolated, sequenced and characterized by Enzyme-Linked Immunosorbent Assay (ELISA). Four phage-antibody clones specifically recognized the toxin. A competitive ELISA assay was optimized with one of these phage antibodies giving a very reproducible standard curve with a linear regression (R(2)=0.9945), showing a working range of 0.0005-500ngmL(-1). Several spiked shellfish samples were analysed by competitive ELISA to determine the accuracy of the assay, with a mean recovery rate of 90%. This study demonstrates that phage display libraries provide a valuable system for the easy and rapid generation of specific antibody fragments directed against difficult antigenic targets, such as free small molecules. Large-scale, low-cost production of anti-palytoxin scFv antibodies in Escherichia coli (E. coli) is an exciting prospect for the development of rapid and simple detection methods. Our results suggest that anti-palytoxin phage antibodies could be a valuable tool with competitive ELISA to detect palytoxin in natural shellfish samples.