Investigations into the cardiotoxicity of a toxin from the nematocysts of the jellyfish, Cyanea capillata

Identification of New Angiotensin-Converting Enzyme Inhibitory Peptides Isolated from the Hydrolysate of the Venom of Nemopilema nomurai Jellyfish

Recently, jellyfish venom has gained attention as a promising reservoir of pharmacologically active compounds, with potential applications in new drug development. In this investigation, novel peptides, isolated from the hydrolysates of Nemopilema nomurai jellyfish venom (NnV), demonstrate potent inhibitory activities against angiotensin-converting enzyme (ACE). Proteolytic enzymes-specifically, papain and protamex-were utilized for the hydrolysis under optimized enzymatic conditions, determined by assessing the degree of hydrolysis through the ninhydrin test. Comparative analyses revealed that papain treatment exhibited a notably higher degree of NnV hydrolysis compared to protamex treatment. ACE inhibitory activity was quantified using ACE kit-WST, indicating a substantial inhibitory effect of 76.31% for the papain-digested NnV crude hydrolysate, which was validated by captopril as a positive control. The separation of the NnV-hydrolysate using DEAE sepharose weak-anion-exchange chromatography revealed nine peaks under a 0-1 M NaCl stepwise gradient, with peak no. 3 displaying the highest ACE inhibition of 96%. The further purification of peak no. 3 through ODS-C18 column reverse-phase high-performance liquid chromatography resulted in five sub-peaks (3.1, 3.2, 3.3, 3.4, and 3.5), among which 3.2 exhibited the most significant inhibitory activity of 95.74%. The subsequent analysis of the active peak (3.2) using MALDI-TOF/MS identified two peptides with distinct molecular weights of 896.48 and 1227.651. The peptide sequence determined by MS/MS analysis revealed them as IVGRPLANG and IGDEPRHQYL. The docking studies of the two ACE-inhibitory peptides for ACE molecule demonstrated a binding affinity of -51.4 ± 2.5 and -62.3 ± 3.3 using the HADDOCK scoring function.

Jellyfish venom proteins and their pharmacological potentials: A review

Several research in the organisms of marine invertebrates to assess the medicinal ability of its bio-active molecules have yielded very positive results in recent times. Jellyfish secreted venoms are rich sources of toxins intended to catch prey or deter predators among invertebrate species, but they may also have harmful effects on humans. The nematocyst, a complex intracellular system that injects a venomous mixture into prey or predators that come into contact with the tentacles or other parts of the body of cnidarians, determines the venomous existence of cnidarians. Nematocyst venoms are mixtures of peptides, proteins and other components that in laboratory animals can induce cytotoxicity, blockade of ion channels, membrane pore formation, in vivo cardiovascular failure and lethal effects. There are also valuable pharmacological and biological aspects of jellyfish venoms. In the present review, overviews of the variety of possible toxin families in cnidarian venoms are addressed in this analysis and these potential toxins are surveyed with those from other cnidarians that offer insight into their potential functions such as anti-oxidant, anti-cancer activity and much more. This research review will provide awareness of the growing repertoire of jellyfish venom proteins and will help to further isolate and classify particular proteins to understand its structure and functional relationship.

Combined Proteome and Toxicology Approach Reveals the Lethality of Venom Toxins from Jellyfish Cyanea nozakii

Jellyfish are a type of poisonous cnidarian invertebrate that secrete lethal venom for predation or defense. Human beings often become victims of jellyfish stings accidentally while swimming or fishing and suffer severe pain, itching, swelling, inflammation, shock, and even death. Jellyfish venom is composed of various toxins, and the lethal toxin is the most toxic and hazardous component of the venom, which is responsible for deaths caused by jellyfish stings and envenomation. Our previous study revealed many toxins in jellyfish venom, including phospholipase A2, metalloproteinase, and protease inhibitors. However, it is still unknown which type of toxin is lethal and how it works. Herein a combined toxicology analysis, proteome strategy, and purification approach was employed to investigate the lethality of the venom of the jellyfish Cyanea nozakii. Toxicity analysis revealed that cardiotoxicity including acute myocardial infarction and a significant decrease in both heart rate and blood pressure is the primary cause of death. Purified lethal toxin containing a fraction of jellyfish venom was subsequently subjected to proteome analysis and bioinformation analysis. A total of 316 and 374 homologous proteins were identified, including phospholipase A2-like toxins and metalloprotease-like toxins. Furthermore, we confirmed that the lethality of the jellyfish venom is related to metalloproteinase activity but without any phospholipase A2 activity or hemolytic activity. Altogether, this study not only provides a comprehensive understanding of the lethal mechanism of jellyfish venom but also provides very useful information for the therapeutic or rescue strategy for severe jellyfish stings.

To Pee, or Not to Pee: A Review on Envenomation and Treatment in European Jellyfish Species

There is a growing cause for concern on envenoming European species because of jellyfish blooms, climate change and globalization displacing species. Treatment of envenomation involves the prevention of further nematocyst release and relieving local and systemic symptoms. Many anecdotal treatments are available but species-specific first aid response is essential for effective treatment. However, species identification is difficult in most cases. There is evidence that oral analgesics, seawater, baking soda slurry and 42-45 °C hot water are effective against nematocyst inhibition and giving pain relief. The application of topical vinegar for 30 s is effective on stings of specific species. Treatments, which produce osmotic or pressure changes can exacerbate the initial sting and aggravate symptoms, common among many anecdotal treatments. Most available therapies are based on weak evidence and thus it is strongly recommended that randomized clinical trials are undertaken. We recommend a vital increase in directed research on the effect of environmental factors on envenoming mechanisms and to establish a species-specific treatment. Adequate signage on jellyfish stings and standardized first aid protocols with emphasis on protective equipment and avoidance of jellyfish to minimize cases should be implemented in areas at risk.

Comparison of haemolytic activity of tentacle-only extract from jellyfish Cyanea capillata in diluted whole blood and erythrocyte suspension: diluted whole blood is a valid test system for haemolysis study

In this paper, we utilized two different test systems to compare the haemolysis of tentacle-only extract (TOE) devoid of nematocysts from jellyfish Cyanea capillata, the 1% whole blood and 0.45% erythrocyte suspension approximately with the same erythrocyte concentration from the blood samples of sheep, rabbit, mouse, rat and human, respectively. Without exception, the haemolytic activity of TOE was dose-dependent in both test systems from all the five kinds of blood samples, while it was generally stronger in erythrocyte suspension than that in diluted whole blood at the relatively high concentration of TOE. When various aliquots of plasma were added into the erythrocyte suspension test system, the haemolytic activity of TOE was declined with the plasma quantity increasing, and dropped to about 20% at the presence of two aliquots of plasma. If serum albumin of 0.5 mg/ml, approximately the same albumin content in 1% whole blood, was added into the erythrocyte suspension test system instead, the haemolysis of TOE was similarly inhibited. The effects of GSH, ascorbic acid and protease inhibitor on the haemolytic activity of TOE were detected in the erythrocyte suspension and diluted whole blood simultaneously, and the test results were coincident between the two systems. These results suggested that the inconsistency of TOE haemolysis between the erythrocyte suspension and diluted whole blood is a universal occurrence in the mammals, and blood plasma plays a dose-dependent protective role against haemolysis which may be due to serum albumin. Diluted whole blood is a valid and convenient test system for haemolysis study in vitro.

A novel proteinaceous cytotoxin from the northern Scyphozoa Cyanea capillata (L.) with structural homology to cubozoan haemolysins

It is well known that jellyfish are producers of complex mixtures of proteinaceous toxins for prey capture and defence. Nevertheless, studies on boreal scyphozoans concerning venom composition and toxic effects are rare. Here the isolation of a novel cytotoxic protein from the fishing tentacle venom of Cyanea capillata (L. 1758) using bioactivity-guided, multidimensional liquid chromatography is described. The crude venom was purified utilising preparative size-exclusion, ion-exchange, and reversed-phase chromatography. The cytotoxicity of resulting chromatographic fractions has been proven by a dye-uptake assay with the human hepatocyte cell line HepG2. The final purification step yielded, among other fractions, a fraction containing a single protein (named CcTX-1) with a molecular weight of its main isoform of 31.17 kDa The purification process leads to an increased cytotoxic activity per protein equivalents and the finally isolated CcTX-1 caused a nearly total loss of cell viability at a protein concentration of 1.3 μg mL⁻¹ corresponding to 0.4 μg/10⁵ cells. De novo sequencing of CcTX-1 was conducted after enzymatic digestion and subsequent matrix-assisted laser desorption ionisation time-of-flight/time-of-flight mass spectrometry (MALDI-ToF/ToF MS/MS). The obtained sequence data provide an approximate 85% description of the amino acid sequence. This sequence information partially matched that of two known haemolytic proteins of two cubozoan species: CaTX-1 from Carybdea alata Reynaud, 1830 and CrTX-1 from Carybdea rastonii Haacke, 1886.

In vitro and in vivo haemolytic studies of tentacle-only extract from jellyfish Cyanea capillata

To approach the real haemolytic process of jellyfish toxins, both in vitro and in vivo haemolysis of tentacle-only extract (TOE) from jellyfish Cyanea capillata has been studied. Dose-response curves of the haemolytic activity of TOE in vitro were sigmoid shaped in both erythrocyte suspension and diluted whole blood, with the former more sensitive to TOE. The in vivo haemolysis increased sharply in the first 10 min and was followed by a gradual increase in the following 3h, with increasing blood potassium and lactic acid accordingly. SC5b-9 complexes were significantly up-regulated in vitro, but not in vivo. These results showed that the haemolysis of TOE in diluted whole blood and in vivo is not totally consistent with that in the erythrocyte suspension, and blood plasma might play a protective role against haemolysis. Thus we suggested that erythrocyte suspension can be used to test the damage of toxin on erythrocyte membrane, while the diluted whole blood may be more suitable to test the haemolysis of toxins.

Comparative study on the cell toxicity and enzymatic activity of two northern scyphozoan species Cyanea capillata (L.) and Cyanea lamarckii (Péron & Léslieur)

Two species of venomous pelagic cnidaria are compared according to their enzymatic, cytotoxic and haemolytic potency. The widely distributed jellyfish Cyanea capillata and Cyanea lamarckii were collected in the North Sea at the coasts of the Orkney Island and the Island of Helgoland. Purified cnidocyst extracts from fishing and mesenteric tentacles were prepared and tested for their bioactivity. The haemolysis induced by toxins of C. capillata was determined with respect to organism size and toxigenic organs. The haemolytic activity of the related species C. lamarckii was documented for the first time. Dose dependent haemolytic activities have been detected by means of protein equivalents at concentrations above 20mug(protein)/mL. Extracts of fishing tentacle cnidocysts showed a less potent haemolytic activity compared to extracts of mesenteric tentacles. In vitro studies with permanent cells of a hepatoma cell line have shown a time and concentration dependent loss of cell vitality up to 90% at 33.3mug(protein)/mL (10mug(protein)/10(5) cells). Supplementing the cell based toxicity tests an enzyme assay was performed to measure a phospholipase A(2) (PLA(2)) activity. A PLA(2)-like activity could be demonstrated in cnidocysts extracts prepared from mesenteric and fishing tentacles of both jellyfish species.

Australian venomous jellyfish, envenomation syndromes, toxins and therapy

The seas and oceans around Australia harbour numerous venomous jellyfish. Chironex fleckeri, the box jellyfish, is the most lethal causing rapid cardiorespiratory depression and although its venom has been characterised, its toxins remain to be identified. A moderately effective antivenom exists which is also partially effective against another chirodropid, Chiropsalmus sp. Numerous carybdeids, some unidentified, cause less severe illness, including Carybdea rastoni whose toxins CrTX-A and CrTX-B are large proteins. Carukia barnesi, another small carybdeid is one cause of the 'Irukandji' syndrome which includes delayed pain from severe muscle cramping, vomiting, anxiety, restlessness, sweating and prostration, and occasionally severe hypertension and acute cardiac failure. The syndrome is in part caused by release of catecholamines but the cause of heart failure is undefined. The venom contains a sodium channel modulator. Two species of Physalia are present and although one is potentially lethal, has not caused death in Australian waters. Other significant genera of jellyfish include Tamoya, Pelagia, Cyanea, Aurelia and Chyrosaora.

Venomous pelagic coelenterates: chemistry, toxicology, immunology and treatment of their stings

Ten years have elapsed since our last review article on the toxicology of venomous pelagic coelenterates was published (Burnett and Calton, 1977). Investigation on important medusae and the chemistry of their nematocyst venoms have been expanding. The venomous jellyfish discussed here include the Portuguese man-o'war, (Physalia physalis), the sea nettle (Chrysaora quinquecirrha), the box jellyfish (Chironex fleckeri and/or Chiropsalmus quadrigatus), the cabbage head jellyfish (Stomolophus meleagris), the lion's mane jellyfish (Cyanea capillata), the Irukandji jellyfish (Carukia barnesi), the Moreton Bay Carybdeid medusa (Morbakka), and the mauve blubber (Pelagia noctiluca).

Actions of cardiotoxins from the southern Chinese cobra (Naja naja atra) on rat cardiac tissue

The cardiotoxic actions of southern Chinese cobra (Naja naja atra) venom have been investigated. Cardiotoxicity accounted for lethality of crude venom in anaesthetized rats and cardiotoxic polypeptides constituted the bulk of the venom when it was fractionated by CM-Sephadex chromatography. The cardiotoxic actions of these polypeptides were investigated in isolated cardiac tissue. Actions of cardiotoxins on rate, force and intracellular potentials occurred more readily in ventricular tissue and were reversible in all cardiac tissues. Bolus injections of cardiotoxins to perfused rat hearts produced profound changes in intracellular potentials, but such changes were reversed by 10 min after toxin wash-out. The changes included depolarization and loss of the fast phase (0) of the action potential. The loss of beating and contracture produced by cardiotoxins in isolated atria and ventricles showed such marked tachyphylaxis that toxicity was lost after 2-5 exposures. Both calcium and heparin ameliorated the cardiotoxic actions of cardiotoxins. Since the actions of cardiotoxin were partially selective for ventricular tissue, reversible, demonstrated tachyphylaxis and could be prevented, it is suggested that a specific molecular mechanism may be involved, rather than a non-specific action such as cell membrane destruction.

Interrelationships between toxins: studies on the cross-reactivity between bacterial or animal toxins and monoclonal antibodies to two jellyfish venoms

Affinity chromatography on columns of immobilized anti-Chrysaora and anti-Physalia monoclonal antibodies can be an effective purification tool for animal and bacterial toxins. Furthermore, the fact that specific fractions of a given species obtained from immunochromatography columns prepared with either monoclonal antibody possessed identical protein bands, were quantitatively similar in in vitro cardiotoxicity and bound like amounts of antibody, as indicated by the enzyme-linked immunosorbent assay, suggested that antigenic targets of the two monoclonal antibodies are cross-reactive and/or are located on the same molecule. Additional enzyme-linked immunosorbent assays were conducted using non-coelenterate toxins. The significant binding of brown recluse spider venom and purified cholera toxin to both our monoclonal antibodies indicated that these toxic substances shared a common or cross-reacting antigenic site(s) with some coelenterate venoms.

Sea nettle (Chrysaora quinquecirrha) nematocyst venom: mechanism of action on muscle

The cellular mechanism of toxicity of sea nettle nematocyst venom was studied in the isolated, perfused frog ventricle and the isolated frog sartorius muscle. The venom depolarized both cardiac muscle fibers and sartorius fibers and shortened the duration of the ventricular action potential. Sodium content was increased, potassium content was decreased and magnesium content was unaltered in both tissues upon exposure to venom. Calcium content increased in heart ventricle, twitch tension decreased and a contracture developed. The calcium content of venom-treated, quiescent sartorius muscles was not changed from control. In stimulated sartorius muscles, tetanus tension fell during venom treatment, the twitch response was variable and no contracture was seen. Venom-treated sartorius muscles incubated with 5 mM Rb+, Cs+ or Li+ took up twice the amount of each cation as did control muscles. Sea nettle venom decreased the resistance of black lipid membranes in discrete steps, each step corresponding to a transfer of about 2 X 10(7) ions/sec at a potential of 20 mV in Ringer's solution. It was concluded that a component of sea nettle venom forms a monovalent cation channel in cardiac skeletal muscle surface membranes that allows a rapid influx of sodium into the cell.

The automated counting of beating rates in individual cultured heart cells

The effect of drugs on the beating rate of cultured heart cells can be monitored in a number of ways. The simultaneous automated measurement of beating rates of a number of cells allows drug effects to be rapidly quantified. A photoresistive detector placed on a television image of a cell, when coupled to operational amplifiers, gives binary signals that can be processed by a microprocessor. On this basis, we have devised a system that is capable of simultaneously monitoring the individual beating of six single cultured heart cells. A microprocessor automatically processes data obtained under different experimental conditions and records it in suitable descriptive formats such as dose-response curves and double reciprocal plots.

Prostaglandins have limited actions on abnormalities of beating induced in cultured heart cells

Prostaglandins are antiarrhythmic in a variety of situations including ischaemic arrhythmias, but the mechanisms involved are not known. In view of this, the protective actions of prostaglandins A2, E2, F1 alpha, F2 beta, and I2 against abnormalities of beating induced in cultured heart cells were investigated. Abnormalities of beating were induced in single cells by variety of agents including ouabain Ca++, K+, dinitrophenol (DNP), and toxic material from the jellyfish Cyanea. Abnormalities were assessed in terms of rate, rate range, subjective arrhythmic behaviour and percent cells beating. The prostaglandins (at 10(-7)-10(-5) M) were added with the arrhythmogenic agent to test for their ability to modify agent-induced beating abnormalities and were compared with lidocaine and quinidine. Prostaglandins alone had minimal direct effects on the cells and only minimally reduced responses to arrhythmogenic agents. The most protective prostaglandins, PGE2 and PGF1 alpha, tended to normalise beating behaviour most noticeably in DNP-treated cells, unlike lidocaine and quinidine which were effective against Ca++-induced changes while worsening those of K+. Thus, a general ability to protect disturbed cardiac cells is not seen with high concentrations of prostaglandins.