Snake venom proteins acting on hemostasis

The Role of Snake Venom Proteins in Inducing Inflammation Post-Envenomation: An Overview on Mechanistic Insights and Treatment Strategies

The intricate combination of organic and inorganic compounds found in snake venom includes proteins, peptides, lipids, carbohydrates, nucleotides, and metal ions. These components work together to immobilise and consume prey through processes such as paralysis and hypotension. Proteins, both enzymatic and non-enzymatic, form the primary components of the venom. Based on the effects they produce, venom can be classified as neurotoxic, hemotoxic, and cytotoxic. Studies have shown that, after envenomation, proteins in snake venom also contribute significantly to the induction of inflammatory responses which can either have systemic or localized consequences. This review delves into the mechanisms by which snake venom proteins trigger inflammatory responses, focusing on key families such as phospholipase A2, metalloproteinases, serine proteases, C-type lectins, cysteine-rich secretory proteins, and L-amino acid oxidase. In addition, the role of venom proteins in activating various inflammatory pathways, including the complement system, inflammasomes, and sterile inflammation are also summarized. The available therapeutic options are examined, with a focus on antivenom therapy and its side effects. In general, this review offers a comprehensive understanding of the inflammatory mechanisms that are triggered by snake venom proteins and the side effects of antivenom treatment. All these emphasize the need for effective strategies to mitigate these detrimental effects.

Enhancing snakebite management: The role of small molecule therapeutics in complementing antivenom strategies

The variability in snake composition presents a significant challenge in accessing an effective broad-spectrum antivenom. These highly complex mixtures can result in numerous deleterious effects affecting thousands of individuals worldwide, particularly in Asia, sub-Saharan Africa, and Latin America. While the administration of antivenom remains a recommended treatment for snakebite envenomation and is the primary means to prevent systemic damage, there are limitations concerning specificity, reversal of local effects, and economic factors that hinder the availability of these antibodies. In this review, we have compiled information on the use of small molecule therapeutics in initial first-aid treatments before antivenom administration. These enzyme inhibitors have shown promise as viable candidates to broaden our treatment approaches, simplify procedures, reduce costs, and improve the clinical outcomes of affected patients.

The Clot Thickens: Differential Coagulotoxic and Cardiotoxic Activities of Anguimorpha Lizard Venoms

Despite their evolutionary novelty, lizard venoms are much less studied in comparison to the intense research on snake venoms. While the venoms of helodermatid lizards have long been assumed to be for defensive purposes, there is increasing evidence of toxic activities more useful for predation than defence (such as paralytic neurotoxicity). This study aimed to ascertain the effects of Heloderma, Lanthanotus, and Varanus lizard venoms on the coagulation and cardiovascular systems. Anticoagulant toxicity was demonstrated for the Varanus species studied, with the venoms prolonging clotting times in human and bird plasma due to the destructive cleavage of fibrinogen. In contrast, thromboelastographic analyses on human and bird plasmas in this study demonstrated a procoagulant bioactivity for Heloderma venoms. A previous study on Heloderma venom using factor-depleted plasmas as a proxy model suggested a procoagulant factor was present that activated either Factor XI or Factor XII, but could not ascertain the precise target. Our activation studies using purified zymogens confirmed FXII activation. Comparisons of neonate and adult H. exasperatum, revealed the neonates to be more potent in the ability to activate FXII, being more similar to the venom of the smaller species H. suspectum than the adult H. exasperatum. This suggests potent FXII activation a basal trait in the genus, present in the small bodied last common ancestor. This also indicates an ontogenetic difference in prey preferences in the larger Heloderma species paralleing the change in venom biochemistry. In addition, as birds lack Factor XII, the ability to clot avian plasma suggested an additional procoagulant site of action, which was revealed to be the activation of Factor VII, with H. horridum being the most potent. This study also examined the effects upon the cardiovascular system, including the liberation of kinins from kininogen, which contributes to hypotension induction. This form of toxicity was previously described for Heloderma venoms, and was revealed in this study was to also be a pathophysiological effect of Lanthanotus and Varanus venoms. This suggests that this toxic activity was present in the venom of the last common ancestor of the anguimorph lizards, which is consistent with kallikrein enzymes being a shared toxin trait. This study therefore uncovered novel actions of anguimorph lizard venoms, not only contributing to the evolutionary biology body of knowledge but also revealing novel activities to mine for drug design lead compounds.

Biochemical and toxicological profiles of venoms from an adult female South American bushmaster (Lachesis muta rhombeata) and her offspring

In this work, we compared the biochemical and toxicological profiles of venoms from an adult female specimen of Lachesis muta rhombeata (South American bushmaster) and her seven offspring born in captivity, based on SDS-PAGE, RP-HPLC, enzymatic, coagulant, and hemorrhagic assays. Although adult and juvenile venoms showed comparable SDS-PAGE profiles, juveniles lacked some chromatographic peaks compared with adult venom. Adult venom had higher proteolytic (caseinolytic) activity than juvenile venoms (p < 0.05), but there were no significant inter-venom variations in the esterase, PLA2, phosphodiesterase and L-amino acid oxidase (LAAO) activities, although the latter activity was highly variable among the venoms. Juveniles displayed higher coagulant activity on human plasma, with a minimum coagulant dose ∼42% lower than the adult venom (p < 0.05), but there were no age-related differences in thrombin-like activity. Adult venom was more fibrinogenolytic (based on the rate of fibrinogen chain degradation) and hemorrhagic than juvenile venoms (p < 0.05). The effective dose of Bothrops/Lachesis antivenom (produced by the Instituto Butantan) needed to neutralize the coagulant activity was ∼57% greater for juvenile venoms (p < 0.05), whereas antivenom did not attenuate the thrombin-like activity of juvenile and adult venoms. Antivenom significantly reduced the hemorrhagic activity of adult venom (400 μg/kg, i. d.), but not that of juvenile venoms. Overall, these data indicate a compositional and functional ontogenetic shift in L. m. rhombeata venom.

Daboxin P, a phospholipase A2 of Indian Daboia russelii venom, modulates thrombin-mediated platelet aggregation

Daboxin P, reported earlier from the venom of Daboia russellii, disturbs the blood coagulation cascade by targeting factor X and factor Xa. The present study exhibits that Daboxin P also inhibits platelet aggregation induced by various agonists. The thrombin-induced platelet aggregation was inhibited maximum whereas inhibition of collagen-induced platelet aggregation was found to be 50% and no inhibition of adenosine diphosphate (ADP) and arachidonic acid-induced aggregation was observed. Daboxin P dose-dependently inhibited the thrombin-induced platelet aggregation with Anti-Aggregation 50 (AD50 ) dose of 55.166 nM and also reduced the thrombin-mediated calcium influx. In-silico interaction studies suggested that Daboxin P binds to thrombin and blocks its interaction with its receptor on the platelet surface. Quenching of thrombin's emission spectrum by Daboxin P and electrophoretic profiles of pull-down assay further reveals the binding between Daboxin P and thrombin. Thus, the present study demonstrates that Daboxin P inhibits thrombin-induced platelet aggregation by binding to thrombin.

Comparing Traditional and Toxin-Oriented Approaches towards Antivenom Production against Bitis arietans Snake Venom

Accidents with snakes are responsible for about 32,000 deaths annually in sub-Saharan Africa, caused mostly by snakes from the genus Bitis, in particular Bitis arietans. B. arietans venom is composed of a complex mixture of toxins, mainly metalloproteases, serine proteases, phospholipases, lectins, and disintegrins. In this work, we compared two approaches to anti-B. arietans antivenom production: immunization with crude snake venom ("traditional approach") and immunization with selected key toxins isolated from the snake venom ("toxin oriented" approach). Fractions from B. arietans venom were isolated by size exclusion chromatography. Crude venom and samples containing serine proteases or metalloproteases were selected for the immunization of BALB/c mice. Anti-B. arietans and anti-serine proteases plasmas showed a similar recognition profile and higher titers and affinity than the anti-metalloproteases plasma. Cross-recognition of other Bitis venoms was observed, but with low intensity. Although the plasma of all experimental groups inhibited the enzymatic activity of B. arietans venom in vitro, in vivo protection was not achieved. Our results have shown limitations in both approaches considered. Based on this, we proposed a model of polyclonal, species-specific, monovalent antivenoms that could be used as a base to produce customizable polyvalent sera for use in sub-Saharan Africa.

Effectiveness of hemocoagulase, tranexamic acid, and their combination for reducing blood loss in bimaxillary orthognathic surgery: a retrospective study

Objectives

Orthognathic surgery is a corrective intervention for maxillofacial deformities. Bleeding is a major concern for oral and maxillofacial surgeons. Various agents, such as hemocoagulase, tranexamic acid, and aprotinin have been developed to reduce intraoperative bleeding and transfusion requirements. Therefore, in this study we aimed to investigate the effects of hemocoagulase and tranexamic acid, as well as their simultaneous use, to reduce bleeding during orthognathic surgery. Patients and.

Methods

This retrospective study included patients who had undergone simultaneous orthognathic surgery of the maxilla and mandible between January 2013 and September 2022 and were classified into three groups based on drugs administered: hemocoagulase (Botropase), tranexamic acid, and a combination of both drugs. We recorded patient age, sex, weight, blood loss, and duration of surgery. Red blood cell (RBC), hemoglobin, hematocrit, and platelet levels were measured before, immediately after, and one day after surgery.

Results

No statistically significant differences were found in blood loss, RBC, hemoglobin, hematocrit, or platelet levels between any of the groups. There were no differences in the drug effects between Le Fort I and bilateral mandibular sagittal split osteotomies, with or without double genioplasty. However, there were significant reductions in RBC, hemoglobin, hematocrit, and platelet levels during genioplasty.

Conclusion

Tranexamic acid, hemocoagulase, and their combination had similar efficacy in patients who underwent Le Fort Ⅰ and bilateral mandibular sagittal split osteotomies with and without genioplasty.

Animal Toxins: A Historical Outlook at the Institut Pasteur of Paris

Humans have faced poisonous animals since the most ancient times. It is recognized that certain animals, like specific plants, produce toxic substances that can be lethal, but that can also have therapeutic or psychoactive effects. The use of the term "venom", which initially designated a poison, remedy, or magic drug, is now confined to animal poisons delivered by biting. Following Louis Pasteur's work on pathogenic microorganisms, it was hypothesized that venoms could be related to bacterial toxins and that the process of pathogenicity attenuation could be applied to venoms for the prevention and treatment of envenomation. Cesaire Phisalix and Gabriel Bertrand from the National Museum of Natural History as well as Albert Calmette from the Institut Pasteur in Paris were pioneers in the development of antivenomous serotherapy. Gaston Ramon refined the process of venom attenuation for the immunization of horses using a formalin treatment method that was successful for diphtheria and tetanus toxins. This paved the way for the production of antivenomous sera at the Institut Pasteur, as well as for research on venom constituents and the characterization of their biological activities. The specific activities of certain venom components, such as those involved in blood coagulation or the regulation of chloride ion channels, raises the possibility of developing novel therapeutic drugs that could serve as anticoagulants or as a treatment for cystic fibrosis, for example. Scientists of the Institut Pasteur of Paris have significantly contributed to the study of snake venoms, a topic that is reported in this review.

The Venom Composition of the Snake Tribe Philodryadini: 'Omic' Techniques Reveal Intergeneric Variability among South American Racers

Snakes of the Philodryadini tribe are included in the Dipsadidae family, which is a diverse group of rear-fanged snakes widespread in different ecological conditions, including habitats and diet. However, little is known about the composition and effects of their venoms despite their relevance for understanding the evolution of these snakes or even their impact on the occasional cases of human envenoming. In this study, we integrated venom gland transcriptomics, venom proteomics and functional assays to characterize the venoms from eight species of the Philodryadini tribe, which includes the genus Philodryas, Chlorosoma and Xenoxybelis. The most abundant components identified in the venoms were snake venom metalloproteinases (SVMPs), cysteine-rich secretory proteins (CRISPs), C-type lectins (CTLs), snake endogenous matrix metalloproteinases type 9 (seMMP-9) and snake venom serinoproteinases (SVSPs). These protein families showed a variable expression profile in each genus. SVMPs were the most abundant components in Philodryas, while seMMP-9 and CRISPs were the most expressed in Chlorosoma and Xenoxybelis, respectively. Lineage-specific differences in venom composition were also observed among Philodryas species, whereas P. olfersii presented the highest amount of SVSPs and P. agassizii was the only species to express significant amounts of 3FTx. The variability observed in venom composition was confirmed by the venom functional assays. Philodryas species presented the highest SVMP activity, whereas Chlorosoma species showed higher levels of gelatin activity, which may correlate to the seMMP-9 enzymes. The variability observed in the composition of these venoms may be related to the tribe phylogeny and influenced by their diets. In the presented study, we expanded the set of venomics studies of the Philodryadini tribe, which paves new roads for further studies on the evolution and ecology of Dipsadidae snakes.

New Insights into Immunopathology Associated to Bothrops lanceolatus Snake Envenomation: Focus on PLA2 Toxin

The systemic increase in inflammatory mediator levels can induce diverse pathological disorders, including potentially thrombus formation, which may be lethal. Among the clinical conditions in which the formation of thrombi dictates the patient's prognosis, envenomation by Bothrops lanceolatus should be emphasized, as it can evolve to stroke, myocardial infarction and pulmonary embolism. Despite their life-threatening potential, the immunopathological events and toxins involved in these reactions remain poorly explored. Therefore, in the present study, we examined the immunopathological events triggered by a PLA₂ purified from B. lanceolatus venom, using an ex vivo human blood model of inflammation. Our results showed that the purified PLA₂ from the venom of B. lanceolatus damages human erythrocytes in a dose dependent way. The cell injury was associated with a decrease in the levels of CD55 and CD59 complement regulators on the cell surface. Moreover, the generation of anaphylatoxins (C3a and C5a) and the soluble terminal complement complex (sTCC) indicates that human blood exposure to the toxin activates the complement system. Increased production of TNF-α, CXCL8, CCL2 and CCL5 followed complement activation. The venom PLA₂ also triggered the generation of lipid mediators, as evidenced by the detected high levels of LTB₄, PGE₂ and TXB₂. The scenario here observed of red blood cell damage, dysfunctions of the complement regulatory proteins, accompanied by an inflammatory mediator storm, suggests that B. lanceolatus venom PLA₂ contributes to the thrombotic disorders present in the envenomed individuals.

Cloning and functional analysis of a trypsin-like serine protease from Pinctada fucata martensii

Trypsin-like serine proteases (TLSs) play various roles in dietary protein digestion, hemolymph coagulation, antimicrobial peptide synthesis, and, in particular, the rapid immune pathways activated in response to pathogen detection. The cultured pearl industry, of which Pinctada fucata martensii is one of the most important species, is plagued by disease, thus leading to large economic losses. Herein, the molecular mechanisms underlying the innate immune response of P.f. martensii were explored. First, immune effector molecules from the P.f. martensii genome were screened and a TLS-like gene encoding a protein with a trypsin domain, herein designated as PmTLS, was identified. A multi-sequence alignment indicated a low sequence homology between PmTLS and other mollusk TLS-like proteins. Furthermore, a neighbor-joining phylogenetic analysis indicated that PmTLS has the closest genetic relationship to a Crassostrea gigas TLS. Additionally, real-time quantitative PCR (qPCR) analysis showed that PmTLS mRNA is constitutively expressed in all of the 6 examined P.f. martensii tissues, with significantly higher expression noted in hemocytes relative to the other tissues examined (p < 0.05). P.f. martensii samples were then challenged with various pathogen-associated molecular patterns (PAMPs), including lipopolysaccharide, peptidoglycan, and polyinosinic acid. In the challenge groups, PmTLS was significantly upregulated in hemocytes at 48 h post-challenge when compared to the unchallenged controls. Furthermore, treatment with recombinant PmTLS (rPmTLS) also significantly inhibited the growth of most of the examined gram-negative bacteria tested in vitro (p < 0.05), but it had little effect on the growth of the examined gram-positive bacteria. When examining morphological changes via transmission electron microscopy, rPmTLS treated bacteria exhibited morphological changes such as plasma wall separation. Thus, rPmTLS appears to play a bactericidal role by destroying bacterial cell membranes or cell walls, which subsequently leads to a release of the cellular contents and cell death. The findings presented herein have enabled further characterization of the immune defense mechanisms in P.f. martensii and may lead to improved disease control methods for the pearl cultivation industry.

Bioactive Molecules Derived from Snake Venoms with Therapeutic Potential for the Treatment of Thrombo-Cardiovascular Disorders Associated with COVID-19

As expected, several new variants of Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2) emerged and have been detected around the world throughout this Coronavirus Disease of 2019 (COVID-19) pandemic. Currently, there is no specific developed drug against COVID-19 and the challenge of developing effective antiviral strategies based on natural agents with different mechanisms of action becomes an urgent need and requires identification of genetic differences among variants. Such data is used to improve therapeutics to combat SARS-CoV-2 variants. Nature is known to offer many biotherapeutics from animal venoms, algae and plant that have been historically used in traditional medicine. Among these bioresources, snake venom displays many bioactivities of interest such as antiviral, antiplatelet, antithrombotic, anti-inflammatory, antimicrobial and antitumoral. COVID-19 is a viral respiratory sickness due to SARS-CoV-2 which induces thrombotic disorders due to cytokine storm, platelet hyperactivation and endothelial dysfunction. This review aims to: (1) present an overview on the infection, the developed thrombo-inflammatory responses and mechanisms of induced thrombosis of COVID-19 compared to other similar pathogenesis; (2) underline the role of natural compounds such as anticoagulant, antiplatelet and thrombolytic agents; (3) investigate the management of coagulopathy related to COVID-19 and provide insight on therapeutic such as venom compounds. We also summarize the updated advances on antiviral proteins and peptides derived from snake venoms that could weaken coagulopathy characterizing COVID-19.

Erythrocyte haemotoxicity profiling of snake venom toxins after nanofractionation

Snakebite is classified as a priority Neglected Tropical Disease by the World Health Organization. Understanding the pathology of individual snake venom toxins is of great importance when developing more effective snakebite therapies. Snake venoms may induce a range of pathologies, including haemolytic activity. Although snake venom-induced erythrocyte lysis is not the primary cause of mortality, haemolytic activity can greatly debilitate victims and contributes to systemic haemotoxicity. Current assays designed for studying haemolytic activity are not suitable for rapid screening of large numbers of toxic compounds. Consequently, in this study, a high-throughput haemolytic assay was developed that allows profiling of erythrocyte lysis, and was validated using venom from a number of medically important snake species (Calloselasma rhodostoma, Daboia russelii, Naja mossambica, Naja nigricollis and Naja pallida). The assay was developed in a format enabling direct integration into nanofractionation analytics, which involves liquid chromatographic separation of venom followed by high-resolution fractionation and subsequent bioassaying (and optional proteomics analysis), and parallel mass spectrometric detection. Analysis of the five snake venoms via this nanofractionation approach involving haemolytic assaying provided venom-cytotoxicity profiles and enabled identification of the toxins responsible for haemolytic activity. Our results show that the elapid snake venoms (Naja spp.) contained both direct and indirect lytic toxins, while the viperid venoms (C. rhodostoma and D. russelii) only showed indirect lytic activities, which required the addition of phospholipids to exert cytotoxicity on erythrocytes. The haemolytic venom toxins identified were mainly phospholipase A2s and cytotoxic three finger toxins. Finally, the applicability of this new analytical method was demonstrated using a conventional snakebite antivenom treatment and a small-molecule drug candidate to assess neutralisation of venom cytotoxins.

From birth to adulthood: An analysis of the Brazilian lancehead (Bothrops moojeni) venom at different life stages

The Brazilian lancehead (Bothrops moojeni) has a wide distribution in Brazil and represents a serious public health hazard. Previous works reported that the symptoms of snakebites caused by B. moojeni juveniles’ bites were mainly related to coagulation, while those caused by adults’ bites had a more prominent local damage. In this work, we analyzed the venoms of B. moojeni at different life stages to better understand the ontogeny shift in this species. Snakes were grouped by age and sex, and venom pools were formed accordingly. Compositional analyses by one-dimensional electrophoresis (1-DE), chromatography, and mass spectrometry revealed that ontogenetic changes might be mostly related to phospholipase A₂ (PLA₂) and metalloproteases. Regarding the venoms functional aspect, proteolytic, L-amino acid oxidase, PLA₂, and coagulant in vitro activities were assayed, but only the first and the last ones showed age-related changes, with the venom of snakes up to 1 year-old displaying lower proteolytic and higher coagulant activities, while those from 2 years-old onward presented the opposite relation. The venoms of 3 years-old snakes were exceptions to the compositional and functional pattern of adults as both venoms presented profiles similar to neonates. Sex-related differences were observed in specific groups and were not age-related. In vivo experiments (median lethal dose and hemorrhagic activity) were statistically similar between neonates and adults, however we verified that the adult venom killed mice faster comparing to the neonates. All venoms were mostly recognized by the antibothropic serum and displayed similar profiles to 1-DE in western blotting. In conclusion, the Brazilian lancehead venom showed ontogenetic shift in its composition and activities. Furthermore, this change occurred in snakes from 1 to 2 years-old, and interestingly the venom pools from 3 years-old snakes had particular characteristics, which highlights the importance of comprehensive studies to better understand venom variability.

Crotalus Durissus Ruruima: Current Knowledge on Natural History, Medical Importance, and Clinical Toxinology

Crotalus durissus ruruima is a rattlesnake subspecies mainly found in Roraima, the northernmost state of Brazil. Envenomings caused by this subspecies lead to severe clinical manifestations (e.g. respiratory muscle paralysis, rhabdomyolysis, and acute renal failure) that can lead to the victim’s death. In this review, we comprehensively describe C. d. ruruima biology and the challenges this subspecies poses for human health, including morphology, distribution, epidemiology, venom cocktail, clinical envenoming, and the current and future specific treatment of envenomings by this snake. Moreover, this review presents maps of the distribution of the snake subspecies and evidence that this species is responsible for some of the most severe envenomings in the country and causes the highest lethality rates. Finally, we also discuss the efficacy of the Brazilian horse-derived antivenoms to treat C. d. ruruima envenomings in Roraima state.

Slounase, a Batroxobin Containing Activated Factor X Effectively Enhances Hemostatic Clot Formation and Reducing Bleeding in Hypocoagulant Conditions in Mice

Uncontrolled bleeding associated with trauma and surgery is the leading cause of preventable death. Batroxobin, a snake venom-derived thrombin-like serine protease, has been shown to clot fibrinogen by cleaving fibrinopeptide A in a manner distinctly different from thrombin, even in the presence of heparin. The biochemical properties of batroxobin and its effect on coagulation have been well characterized in vitro. However, the efficacy of batroxobin on hemostatic clot formation in vivo is not well studied due to the lack of reliable in vivo hemostasis models. Here, we studied the efficacy of batroxobin and slounase, a batroxobin containing activated factor X, on hemostatic clot composition and bleeding using intravital microcopy laser ablation hemostasis models in micro and macro vessels and liver puncture hemostasis models in normal and heparin-induced hypocoagulant mice. We found that prophylactic treatment in wild-type mice with batroxobin, slounase and activated factor X significantly enhanced platelet-rich fibrin clot formation following vascular injury. In heparin-treated mice, batroxobin treatment resulted in detectable fibrin formation and a modest increase in hemostatic clot size, while activated factor X had no effect. In contrast, slounase treatment significantly enhanced both platelet recruitment and fibrin formation, forming a stable clot and shortening bleeding time and blood loss in wild-type and heparin-treated hypocoagulant mice. Our data demonstrate that, while batroxobin enhances fibrin formation, slounase was able to enhance hemostasis in normal mice and restore hemostasis in hypocoagulant conditions via the enhancement of fibrin formation and platelet activation, indicating that slounase is more effective in controlling hemorrhage.

The plant Stryphnodendron adstringens (Mart.) Coville as a neutralizing source against some toxic activities of Bothrops jararacussu snake venom

Snakebites produce several toxic effects in victims, such as hemorrhage, tissue necrosis, hemostatic, renal, or cardiotoxic alterations, inflammation, and death. To counteract these symptoms, antivenom is the official treatment. Although such therapy prevents death, it does not efficiently neutralize necrosis or other local effects, leading to amputation or morbidities of the affected limb. Therefore, the search for better and more efficient therapies deserves attention; further, plants have been used to ameliorate a number of diseases and medical conditions, including snakebites, for many years. Thus, the aim of this work was to evaluate the antivenom effect of the crude extract, fractions (aqueous and diethyl acetate), and subfractions derived from the aqueous fraction (P1, P2, P3, and P4) of the plant Stryphnodendron adstringens against in vitro (coagulation and proteolytic) and in vivo (edema, hemorrhage, and myotoxic) activities caused by Bothrops jararacussu venom. Overall, all extracts inhibited the toxic effect of B. jararacussu venom, but with different potencies, regardless of whether plant samples were incubated together with venom or injected before or after venom injection into animals; the crude extract and aqueous fraction were found to be the most effective. Indeed, phytochemical and mass spectrometry analysis of S. adstringens samples revealed the presence of flavonols, tannins, and saponins. In conclusion, the plant S. adstringens may represent a promising natural source of molecules to treat the toxic effects associated with envenomation by B. jararacussu snakebites.

Inhibition of platelet aggregation and blood coagulation by a P-III class metalloproteinase purified from Naja atra venom

Snake venom metalloproteinases (SVMPs) are an important component in viperid and crotalid venoms, and these SVMPs play important and versatile roles in the pathogenesis of snakebite envenoming. The SVMPs from elapid venoms are not well elucidated compared with those from viperid and crotalid venoms. Atrase B is a nonhemorrhagic P-III SVMP purified from the Naja atra venom, which possesses a weak fibrinogenolytic activity. In this paper, the activity and mechanism of atrase B against platelet aggregation and blood coagulation were investigated. The in vitro assay showed that atrase B remarkably inhibited ristocetin- and thrombin-induced platelet aggregation by cleavage of the platelet membrane glycoprotein Ib, and the coagulation of normal human plasma, which may be caused by inhibiting coagulation factor VIII predominantly. When atrase B was intravenously injected into rats at doses of 0.05 and 0.30 mg/kg, the activated partial thromboplastin and the thrombin times were significantly prolonged in a dose-dependent manner. Similarly, the fibrinogen level decreased, but only a high dose of atrase B showed remarkable activity against platelet aggregation. Results suggested that anticoagulation was a more important function of atrase B compared with its activity against platelet aggregation. These results indicated that atrase B may play an important role in the anticoagulant properties of Naja atra venom. In addition, atrase B may be a potent anticoagulant agent because its effectiveness in vivo against platelet aggregation and blood coagulation.

From Animal Poisons and Venoms to Medicines: Achievements, Challenges and Perspectives in Drug Discovery

Animal poisons and venoms are comprised of different classes of molecules displaying wide-ranging pharmacological activities. This review aims to provide an in-depth view of toxin-based compounds from terrestrial and marine organisms used as diagnostic tools, experimental molecules to validate postulated therapeutic targets, drug libraries, prototypes for the design of drugs, cosmeceuticals, and therapeutic agents. However, making these molecules applicable requires extensive preclinical trials, with some applications also demanding clinical trials, in order to validate their molecular target, mechanism of action, effective dose, potential adverse effects, as well as other fundamental parameters. Here we go through the pitfalls for a toxin-based potential therapeutic drug to become eligible for clinical trials and marketing. The manuscript also presents an overview of the current picture for several molecules from different animal venoms and poisons (such as those from amphibians, cone snails, hymenopterans, scorpions, sea anemones, snakes, spiders, tetraodontiformes, bats, and shrews) that have been used in clinical trials. Advances and perspectives on the therapeutic potential of molecules from other underexploited animals, such as caterpillars and ticks, are also reported. The challenges faced during the lengthy and costly preclinical and clinical studies and how to overcome these hindrances are also discussed for that drug candidates going to the bedside. It covers most of the drugs developed using toxins, the molecules that have failed and those that are currently in clinical trials. The article presents a detailed overview of toxins that have been used as therapeutic agents, including their discovery, formulation, dosage, indications, main adverse effects, and pregnancy and breastfeeding prescription warnings. Toxins in diagnosis, as well as cosmeceuticals and atypical therapies (bee venom and leech therapies) are also reported. The level of cumulative and detailed information provided in this review may help pharmacists, physicians, biotechnologists, pharmacologists, and scientists interested in toxinology, drug discovery, and development of toxin-based products.

Fibrinogen-clotting enzyme, pictobin, from Bothrops pictus snake venom. Structural and functional characterization

A thrombin-like enzyme, pictobin, was purified from Bothrops pictus snake venom. It is a 41-kDa monomeric glycoprotein as showed by mass spectrometry and contains approx. 45% carbohydrate by mass which could be removed with N-glycosidase. Pictobin coagulates plasma and fibrinogen, releasing fibrinopeptide A and induces the formation of a friable/porous fibrin network as visualized by SEM. The enzyme promoted platelet aggregation in human PRP and defibrination in mouse model and showed catalytic activity on chromogenic substrates S-2266, S-2366, S-2160 and S-2238. Pictobin interacts with the plasma inhibitor α2-macroglobulin, which blocks its interaction with fibrinogen but not with the small substrate BApNA. Heparin does not affect its enzymatic activity. Pictobin cross reacted with polyvalent bothropic antivenom, and its deglycosylated form reduced its catalytic action and antivenom reaction. In breast and lung cancer cells, pictobin inhibits the fibronectin-stimulated migration. Moreover, it produces strong NADH oxidation, mitochondrial depolarization, ATP decrease and fragmentation of mitochondrial network. These results suggest by first time that a snake venom serinprotease produces mitochondrial dysfunction by affecting mitochondrial dynamics and bioenergetics. Structural model of pictobin reveals a conserved chymotrypsin fold β/β hydrolase. These data indicate that pictobin has therapeutic potential in the treatment of cardiovascular disorders and metastatic disease.

Cervical cancer and potential pharmacological treatment with snake venoms

Cervical cancer is the fourth most common cancer worldwide in women. Apoptosis reactivation has become the main strategy for decreasing cancer proliferation. There is a need to extend the search for new drugs to implement more effective and less toxic strategies for cervical cancer treatment. Research has been carried out to find new drugs that have minimal side effects and that focus on the tumor microenvironment, particularly in the induction of cellular apoptosis and cell migration and the inhibition of angiogenesis. Potent toxins from snake venoms have shown potential as sources for the synthesis of new drugs with such characteristics. The present work aimed to describe cervical cancer characteristics, associated risk factors, current treatments and to highlight the effects of toxins isolated from the venom of snakes of the Viperidae family on cervical cancer cell lines.

Proteomics and antivenom immunoprofiling of Russell's viper (Daboia siamensis) venoms from Thailand and Indonesia

The Eastern Russell’s viper, Daboia siamensis, is a WHO Category 1 medically important venomous snake. It has a wide but disjunct distribution in Southeast Asia. The specific antivenom, D. siamensis Monovalent Antivenom (DsMAV-Thailand) is produced in Thailand but not available in Indonesia, where a heterologous trivalent antivenom, Serum Anti Bisa Ular (SABU), is used instead. This study aimed to investigate the geographical venom variation of D. siamensis from Thailand (Ds-Thailand) and Indonesia (Ds-Indonesia), and the immunorecognition of the venom proteins by antivenoms.

Proteo-Transcriptomic Characterization of the Venom from the Endoparasitoid Wasp Pimpla turionellae with Aspects on Its Biology and Evolution

Within mega-diverse Hymenoptera, non-aculeate parasitic wasps represent 75% of all hymenopteran species. Their ovipositor dual-functionally injects venom and employs eggs into (endoparasitoids) or onto (ectoparasitoids) diverse host species. Few endoparasitoid wasps such as Pimpla turionellae paralyze the host and suppress its immune responses, such as encapsulation and melanization, to guarantee their offspring's survival. Here, the venom and its possible biology and function of P. turionellae are characterized in comparison to the few existing proteo-transcriptomic analyses on parasitoid wasp venoms. Multiple transcriptome assembly and custom-tailored search and annotation strategies were applied to identify parasitoid venom proteins. To avoid false-positive hits, only transcripts were finally discussed that survived strict filter settings, including the presence in the proteome and higher expression in the venom gland. P. turionella features a venom that is mostly composed of known, typical parasitoid enzymes, cysteine-rich peptides, and other proteins and peptides. Several venom proteins were identified and named, such as pimplin2, 3, and 4. However, the specification of many novel candidates remains difficult, and annotations ambiguous. Interestingly, we do not find pimplin, a paralytic factor in Pimpla hypochondriaca, but instead a new cysteine inhibitor knot (ICK) family (pimplin2), which is highly similar to known, neurotoxic asilid1 sequences from robber flies.

Unique heterologous fibrin biopolymer with hemostatic, adhesive, sealant, scaffold and drug delivery properties: a systematic review

Fibrin biopolymers, previously referred as "fibrin glue" or "fibrin sealants", are natural biomaterials with diverse applications on health. They have hemostatic, adhesive, sealant, scaffold and drug delivery properties and have become widely used in medical and dental procedures. Historically, these biomaterials are produced from human fibrinogen and human or animal thrombin, and the possibility of transmission of infectious diseases by human blood is not ruled out. In the 1990s, to overcome this problem, a new heterologous biomaterial composed of a thrombin-like enzyme purified from Crotalus durissus terrificus venom and a cryoprecipitate rich in fibrinogen extracted from buffaloes Bubalus bubalis blood has been proposed. Therefore, a systematic review of studies on exclusively heterologous fibrin sealants published between 1989 and 2018 was carried out using the following databases: PubMed, SciELO and Google Scholar. The keyword used was "heterologous fibrin sealant". The search resulted in 35 scientific papers in PubMed, four in SciELO and 674 in Google Scholar. After applying the inclusion/exclusion criteria and complete reading of the articles, 30 studies were selected, which formed the basis of this systematic review. It has been observed that the only completely heterologous sealant is the one produced by CEVAP/UNESP. This heterologous biopolymer is proven effective by several studies published in refereed scientific journals. In addition, clinical trials phase I/II for the treatment of chronic venous ulcers authorized by the Brazilian Health Regulatory Agency (ANVISA) were completed. Preliminary results have indicated a safe and promising effective product. Phase III clinical trials will be proposed and required to validate these preliminary findings.

Omics Technologies for Profiling Toxin Diversity and Evolution in Snake Venom: Impacts on the Discovery of Therapeutic and Diagnostic Agents

Snake venoms are primarily composed of proteins and peptides, and these toxins have developed high selectivity to their biological targets. This makes venoms interesting for exploration into protein evolution and structure-function relationships. A single venom protein superfamily can exhibit a variety of pharmacological effects; these variations in activity originate from differences in functional sites, domains, posttranslational modifications, and the formations of toxin complexes. In this review, we discuss examples of how the major venom protein superfamilies have diversified, as well as how newer technologies in the omics fields, such as genomics, transcriptomics, and proteomics, can be used to characterize both known and unknown toxins.Because toxins are bioactive molecules with a rich diversity of activities, they can be useful as therapeutic and diagnostic agents, and successful examples of toxin applications in these areas are also reviewed. With the current rapid pace of technology, snake venom research and its applications will only continue to expand.

The knockout effect of low doses of gamma radiation on hepatotoxicity induced byEchis Coloratussnake venom in rats.. [DOI: 10.1101/705251]

Echis Coloratusis the most medically important viper in Egypt causing several pathological effects leading to death. Gamma radiation has been used as a venom detoxifying tool in order to extend the lifespan of the immunized animals used in antivenin production process. Thus, the aim of this study is to assess the effects of increasing doses of gamma radiation onEchis Coloratusin vivo through biochemical and histological studies. The results revealed a significant increase in the levels of AST, ALT, ALP and glucose of sera collected from the rats injected with nativeEchis Coloratusvenom compared with the non-envenomed group. On the other hand, biochemical parameters of sera of rats administrated with either 1.5 kGy or 3 kGy irradiated venom were significantly decrease compared with the native venom envenomed group at 2h, 4h and 24h post envenomation. In addition, these results were confirmed by histological studies of rats’ livers. Correspondingly, the sublethal dose injection of nativeEchis Coloratusvenom induced significant alterations in the histological architecture of liver after 2, 4 and 24 h of injection. Concurrently, the administration of both 1.5 kGy and 3 kGy gamma irradiated venom showed fewer histological alterations compared with the native group. In conclusion, the present findings support the idea of using gamma radiation as an effective venom detoxification tool.

Snake Venom Hemotoxic Enzymes: Biochemical Comparison between Crotalus Species from Central Mexico

Snakebite envenoming is a serious medical problem in different areas of the world. In Latin America, the major prevalence is due to snakes of the family Viperidae, where rattlesnakes (Crotalus) are included. They produce hemotoxic venom which causes bleeding, tissue degradation and necrosis. Each venom has several enzymatic activities, producing different effects in the envenoming, doing its clinical effects difficult to study. Comparison between venom molecules is also difficult when different techniques are used, and therefore, their identification/characterization using the same methodology is necessary. In this work, a general biochemical characterization in snake venom of serine proteases (SVSP), phospholipases A₂ (PLA₂), metalloproteases (SVMP) and hyaluronidases (SVH) of Crotalus aquilus (Ca), Crotalus polystictus (Cp) and Crotalus molossus nigrescens (Cmn) was done. Differences in protein pattern, enzyme content and enzymatic activities were observed. All the venoms showed high PLA₂ activity, high molecular weight SVSP, and a wide variety of SVMP and SVH forms. Ca and Cp showed the highest enzymatic activities of SVMP and SVSP trypsin-like and chymotrypsin-like, whereas Cmn showed the highest SVH and similar PLA₂ activity with Ca. All the venoms showed peptides with similar molecular weight to crotamine-like myotoxins. No previous biochemical characterization of C. aquilus has been reported and there are no previous analyses that include these four protein families in these Crotalus venoms.

Functional and biological insights of rCollinein-1, a recombinant serine protease from Crotalus durissus collilineatus

BACKGROUND

The prevalent class of snake venom serine proteases (SVSP) in Viperidae venoms is the thrombin-like enzymes, which, similarly to human thrombin, convert fibrinogen into insoluble fibrin monomers. However, thrombin-like serine proteases differ from thrombin by being unable to activate factor XIII, thus leading to the formation of loose clots and fibrinogen consumption. We report the functional and biological characterization of a recombinant thrombin-like serine protease from Crotalus durissus collilineatus, named rCollinein-1.

METHODS

Heterologous expression of rCollinein-1 was performed in Pichia pastoris system according to a previously standardized protocol, with some modifications. rCollinein-1 was purified from the culture medium by a combination of three chromatographic steps. The recombinant toxin was tested in vitro for its thrombolytic activity and in mice for its edematogenicity, blood incoagulability and effect on plasma proteins.

RESULTS

When tested for the ability to induce mouse paw edema, rCollinein-1 demonstrated low edematogenic effect, indicating little involvement of this enzyme in the inflammatory processes resulting from ophidian accidents. The rCollinein-1 did not degrade blood clots in vitro, which suggests that this toxin lacks fibrinolytic activity and is not able to directly or indirectly activate the fibrinolytic system. The minimal dose of rCollinein-1 that turns the blood incoagulable in experimental mice is 7.5 mg/kg. The toxin also led to a significant increase in activated partial thromboplastin time at the dose of 1 mg/kg in the animals. Other parameters such as plasma fibrinogen concentration and prothrombin time were not significantly affected by treatment with rCollinein-1 at this dose. The toxin was also able to alter plasma proteins in mouse after 3 h of injection at a dose of 1 mg/kg, leading to a decrease in the intensity of beta zone and an increase in gamma zone in agarose gel electrophoresis.

CONCLUSION

These results suggest that the recombinant enzyme has no potential as a thrombolytic agent but can be applied in the prevention of thrombus formation in some pathological processes and as molecular tools in studies related to hemostasis.

New Insights on Moojase, a Thrombin-Like Serine Protease from Bothrops moojeni Snake Venom

Snake venom serine proteases (SVSPs) are enzymes that are capable of interfering in various parts of the blood coagulation cascade, which makes them interesting candidates for the development of new therapeutic drugs. Herein, we isolated and characterized Moojase, a potent coagulant enzyme from Bothrops moojeni snake venom. The toxin was isolated from the crude venom using a two-step chromatographic procedure. Moojase is a glycoprotein with N-linked glycans, molecular mass of 30.3 kDa and acidic character (pI 5.80⁻6.88). Sequencing of Moojase indicated that it is an isoform of Batroxobin. Moojase was able to clot platelet-poor plasma and fibrinogen solutions in a dose-dependent manner, indicating thrombin-like properties. Moojase also rapidly induced the proteolysis of the Aα chains of human fibrinogen, followed by the degradation of the Bβ chains after extended periods of incubation, and these effects were inhibited by PMSF, SDS and DTT, but not by benzamidine or EDTA. RP-HPLC analysis of its fibrinogenolysis confirmed the main generation of fibrinopeptide A. Moojase also induced the fibrinolysis of fibrin clots formed in vitro, and the aggregation of washed platelets, as well as significant amidolytic activity on substrates for thrombin, plasma kallikrein, factor Xia, and factor XIIa. Furthermore, thermofluor analyses and the esterase activity of Moojase demonstrated its very high stability at different pH buffers and temperatures. Thus, studies such as this for Moojase should increase knowledge on SVSPs, allowing their bioprospection as valuable prototypes in the development of new drugs, or as biotechnological tools.

Snake venom components in medicine: From the symbolic rod of Asclepius to tangible medical research and application

Both mythologically and logically, snakes have always fascinated man. Snakes have attracted both awe and fear not only because of the elegant movement of their limbless bodies, but also because of the potency of their deadly venoms. Practically, in 2017, the world health organization (WHO) listed snake envenomation as a high priority neglected disease, as snakes inflict up to 2.7 million poisonous bites, around 100.000 casualties, and about three times as many invalidities on man. The venoms of poisonous snakes are a cocktail of potent compounds which specifically and avidly target numerous essential molecules with high efficacy. The individual effects of all venom toxins integrate into lethal dysfunctions of almost any organ system. It is this efficacy and specificity of each venom component, which after analysis of its structure and activity may serve as a potential lead structure for chemical imitation. Such toxin mimetics may help in influencing a specific body function pharmaceutically for the sake of man's health. In this review article, we will give some examples of snake venom components which have spurred the development of novel pharmaceutical compounds. Moreover, we will provide examples where such snake toxin-derived mimetics are in clinical use, trials, or consideration for further pharmaceutical exploitation, especially in the fields of hemostasis, thrombosis, coagulation, and metastasis. Thus, it becomes clear why a snake captured its symbolic place at the Asclepius rod with good reason still nowadays.

BjSP, a novel serine protease from Bothrops jararaca snake venom that degrades fibrinogen without forming fibrin clots

Snake venom serine proteases (SVSPs) are commonly described as capable of affecting hemostasis by interacting with several coagulation system components. In this study, we describe the isolation and characterization of BjSP from Bothrops jararaca snake venom, a serine protease with distinctive properties. This enzyme was isolated by three consecutive chromatographic steps and showed acidic character (pI 4.4), molecular mass of 28 kDa and N-carbohydrate content around 10%. Its partial amino acid sequence presented 100% identity to a serine protease cDNA clone previously identified from B. jararaca venom gland, but not yet isolated or characterized. BjSP was significantly inhibited by specific serine protease inhibitors and showed high stability at different pH values and temperatures. The enzyme displayed no effects on washed platelets, but was able to degrade fibrin clots in vitro and also the Aα and Bβ chains of fibrinogen differently from thrombin, forming additional fibrinopeptides derived from the Bβ chain, which should be related to its inability to coagulate fibrinogen solutions or platelet-poor plasma. In the mapping of catalytic subsites, the protease showed high hydrolytic specificity for tyrosine, especially in subsite S1. Additionally, its amidolytic activity on different chromogenic substrates suggests possible effects on other factors of the coagulation cascade. In conclusion, BjSP is a serine protease that acts nonspecifically on fibrinogen, generating different Bβ fibrinopeptides and thus not forming fibrin clots. Its distinguished properties in comparison to most SVSPs stimulate further studies in an attempt to validate its potential as a defibrinogenating agent.

Snake Venom Extracellular vesicles (SVEVs) reveal wide molecular and functional proteome diversity

Proteins constitute almost 95% of snake venom's dry weight and are produced and released by venom glands in a solubilized form during a snake bite. These proteins are responsible for inducing several pharmacological effects aiming to immobilize and initiate the pre-digestion of the prey. This study shows that proteins can be secreted and confined in snake venom extracellular vesicles (SVEVs) presenting a size distribution between 50 nm and 500 nm. SVEVs isolated from lyophilized venoms collected from four different species of snakes (Agkistrodon contortrix contortrix, Crotalus atrox, Crotalus viridis and Crotalus cerberus oreganus) were analyzed by mass spectrometry-based proteomic, which allowed the identification of proteins belonging to eight main functional protein classes such as SVMPs, serine proteinases, PLA₂, LAAO, 5'nucleotidase, C-type lectin, CRISP and Disintegrin. Biochemical assays indicated that SVEVs are functionally active, showing high metalloproteinase and fibrinogenolytic activity besides being cytotoxic against HUVEC cells. Overall, this study comprehensively depicts the protein composition of SVEVs for the first time. In addition, the molecular function of some of the described proteins suggests a central role for SVEVs in the cytotoxicity of the snake venom and sheds new light in the envenomation process.

Developing Small Molecule Therapeutics for the Initial and Adjunctive Treatment of Snakebite

The World Health Organization (WHO) recently added snakebite envenoming to the priority list of Neglected Tropical Diseases (NTD). It is thought that ~75% of mortality following snakebite occurs outside the hospital setting, making the temporal gap between a bite and antivenom administration a major therapeutic challenge. Small molecule therapeutics (SMTs) have been proposed as potential prereferral treatments for snakebite to help address this gap. Herein, we discuss the characteristics, potential uses, and development of SMTs as potential treatments for snakebite envenomation. We focus on SMTs that are secretory phospholipase A2 (sPLA2) inhibitors with brief exploration of other potential drug targets on venom molecules.

Anti-Ophidian Properties of Herbal Medicinal Plants: Could it be a Remedy for Snake Bite Envenomation?

Snake bite envenoming causes high rates of morbidity and mortality and is one of the serious health-related concerns all over the globe. Around 3200 species of snakes have been discovered till date. Amid these species, about 1300 species of snakes are venomous. On account of its severity, World Health Organization (WHO) recently included snakebite envenoming in the list of neglected tropical diseases. Immunotherapy has partially solved the issues related to snakebite envenomation. However, it is associated with numerous adverse effects, due to which alternative treatment strategies are required for the treatment of snakebite. Traditionally, a large repository of herbal medicinal plants is known to possess activity against snake venom. An exploration of the therapeutic benefits of these medicinal plants used for the treatment of snakebites reveals the presence of various potential phytochemicals. The aim of the present review is to provide an outline regarding poisonous snakes all over the world, various compositions of snake venom, adverse effects related to anti-snake venom and numerous medicinal plants used for the anti-ophidian activity.

Molecular modeling, biochemical characterization, and pharmacological properties of Cc3 -SPase: A platelet-aggregating thrombin-like enzyme purified from Cerastes cerastes venom

Cc3 -SPase (30 kDa-proteinase; pI 5.98) was isolated from Cerastes cerastes venom. Its sequence of 271 residues yielded from LC-MALDI-TOF showed high degrees of homology when aligned with other proteinases. Cc3 -SPase cleaved natural and synthetic proteins such as casein and fibrinogen leaving fibrin clots unaffected. Cc3 -SPase was fully abolished by ion chelators, whereas aprotinin, antithrombin III (Sigma Aldrich, Saint-Louis, Missouri, USA), and heparin were ineffective. Affinity of Cc3 -SPase to benzamidine indicated the presence of an aspartate residue in the catalytic site as confirmed by three-dimensional structure consisting of 14 β-strands and four α-helices. Molecular mechanisms revealed that Cc3 -SPase is capable of promoting dysfunctional platelet aggregation via two signaling pathways mediated by the G-coupled protein receptors and αIIbβ3 integrin. Cc3 -SPase is involved in both extrinsic/intrinsic coagulation pathways in deficient plasmas by replacing defective/lacking factors FII, FVII, and FVIII but not FX. Cc3 -SPase could substitute missing factors in blood diseases related to plasma factor deficiencies.

Effects of hemocoagulase agkistrodon on the coagulation factors and its procoagulant activities

Objective

Hemocoagulase agkistrodon (HCA), a thrombin-like enzyme (TLE) from the venom of the Chinese moccasin snake (Deinagkistrodon acutus), has been used in clinical practice as a hemostatic compound. The aim of this study was to further investigate the pharmacological properties of HCA.

Materials and methods

Sodium dodecyl sulfate or native polyacrylamide gel electrophoresis (SDS- or N-PAGE) as well as enzyme linked immunosorbent assays (ELISAs) were conducted to study the effects of HCA on the human plasma fibrinogen and prothrombin levels, as well as its in vitro interactions with some coagulation factors. In addition, the bleeding time effects of HCA in the mouse tail-bleeding model as well as its effects on the fibrinogen levels in rabbits were determined in vivo.

Results

In vitro results revealed that HCA exerts its procoagulant activities by hydrolyzing fibrinogen into segments that are easier to be absorbed, reducing the risk of thrombus formation. Besides, HCA could significantly inhibit the activation of prothrombin at the concentration of 0.3 μM. Unexpectedly, we also found that HCA was able to strongly bind to factor X/Xa (in a ratio of 1:1) and thus inhibit the acceleration of active factor X to tissue plasminogen activator-catalyzed plasminogen activation, demonstrating that it could be less likely to lead to thrombus formation. Finally, in vivo results indicated that HCA could significantly shorten the bleeding time in the mouse tail-bleeding model and had no effect on the fibrinogen levels in rabbits.

Conclusion

In summary, HCA, a unique and new family member of TLEs, may become a new clinical drug for the prevention and treatment of hemorrhage due to its unique and complex interactions with the blood system. Clarification of these features will enable us to further understand the mechanism of action of HCA and then promote its further application in clinical practice as a therapeutic drug.

Effectiveness and Safety of Batroxobin, Tranexamic Acid and a Combination in Reduction of Blood Loss in Lumbar Spinal Fusion Surgery

STUDY DESIGN

A prospective randomized double blind placebo controlled trail.

OBJECTIVE

To evaluate and compare the efficacy and safety of batroxobin (botropase), tranexamic acid (TXA), and their combination in reduction of perioperative blood loss in lumbar spine single level fusion surgeries.

SUMMARY OF BACKGROUND DATA

Spinal surgeries are associated with significant blood loss leading to perioperative anemia and increased need for allogenic transfusion. TXA competitively inhibits plasmin and batroxobin converts fibrinogen to fibrin and theoretically their combination is synergistic. Though TXA is widely studied in controlling blood loss, there is little information on use of batroxobin and their combination. Thus, we aimed to study effect and safety of individual drugs and their combination in controlling blood loss in spinal surgery.

METHODS

Hundred patients were randomized into four groups. Group B received batroxobin, group T received TXA, group BT received batroxobin and TXA and group P received placebo. Outcomes assessed are intraoperative and postoperative blood loss, hematocrit, allogenic blood transfusion, and deep vein thrombosis (DVT), postoperatively.

RESULT

Mean intraoperative blood loss in Group B, T, BT, and P were 268.32 ± 62.92 mL, 340.72 ± 182.75 mL, 256.96 ± 82.64 mL, and 448.44 ± 205.86 mL, respectively. Postoperative surgical site drain collection in Group B, T, BT, and P were 218.00 ± 100.54 mL, 260.40 ± 100.85 mL, 191.00 ± 87.84 mL, and 320.00 ± 125.83 mL, respectively. Intraoperative blood loss of Group P was statistically higher than Groups B and BT (P < 0.001). Mean postoperative surgical site drain collection was statistically significant (P < 0.001). No statistically significant differences in fluid administration (P = 0.751), blood transfusion (P = 1.000), preoperative and postoperative hemoglobin (P = 0.090, P = 0.134, respectively), and deep vein thrombosis (P = 1.000).

CONCLUSION

Batroxobin and combination of batroxobin with tranexamic acid significantly reduced perioperative blood loss when compared with placebo.

LEVEL OF EVIDENCE

2.

Are Fireworms Venomous? Evidence for the Convergent Evolution of Toxin Homologs in Three Species of Fireworms (Annelida, Amphinomidae)

Amphinomids, more commonly known as fireworms, are a basal lineage of marine annelids characterized by the presence of defensive dorsal calcareous chaetae, which break off upon contact. It has long been hypothesized that amphinomids are venomous and use the chaetae to inject a toxic substance. However, studies investigating fireworm venom from a morphological or molecular perspective are scarce and no venom gland has been identified to date, nor any toxin characterized at the molecular level. To investigate this question, we analyzed the transcriptomes of three species of fireworms-Eurythoe complanata, Hermodice carunculata, and Paramphinome jeffreysii-following a venomics approach to identify putative venom compounds. Our venomics pipeline involved de novo transcriptome assembly, open reading frame, and signal sequence prediction, followed by three different homology search strategies: BLAST, HMMER sequence, and HMMER domain. Following this pipeline, we identified 34 clusters of orthologous genes, representing 13 known toxin classes that have been repeatedly recruited into animal venoms. Specifically, the three species share a similar toxin profile with C-type lectins, peptidases, metalloproteinases, spider toxins, and CAP proteins found among the most highly expressed toxin homologs. Despite their great diversity, the putative toxins identified are predominantly involved in three major biological processes: hemostasis, inflammatory response, and allergic reactions, all of which are commonly disrupted after fireworm stings. Although the putative fireworm toxins identified here need to be further validated, our results strongly suggest that fireworms are venomous animals that use a complex mixture of toxins for defense against predators.

A New Platelet-Aggregation-Inhibiting Factor Isolated from Bothrops moojeni Snake Venom

This work reports the purification and functional characterization of BmooPAi, a platelet-aggregation-inhibiting factor from Bothrops moojeni snake venom. The toxin was purified by a combination of three chromatographic steps (ion-exchange on DEAE-Sephacel, molecular exclusion on Sephadex G-75, and affinity chromatography on HiTrap™ Heparin HP). BmooPAi was found to be a single-chain protein with an apparent molecular mass of 32 kDa on 14% SDS-PAGE, under reducing conditions. Sequencing of BmooPAi by Edman degradation revealed the amino acid sequence LGPDIVPPNELLEVM. The toxin was devoid of proteolytic, haemorrhagic, defibrinating, or coagulant activities and induced no significant oedema or hyperalgesia. BmooPAi showed a rather specific inhibitory effect on ristocetin-induced platelet aggregation in human platelet-rich plasma, whereas it had little or no effect on platelet aggregation induced by collagen and adenosine diphosphate. The results presented in this work suggest that BmooPAi is a toxin comprised of disintegrin-like and cysteine-rich domains, originating from autolysis/proteolysis of PIII SVMPs from B. moojeni snake venom. This toxin may be of medical interest because it is a platelet aggregation inhibitor, which could potentially be developed as a novel therapeutic agent to prevent and/or treat patients with thrombotic disorders.

The role of platelets in hemostasis and the effects of snake venom toxins on platelet function

The human body has a set of physiological processes, known as hemostasis, which keeps the blood fluid and free of clots in normal vessels; in the case of vascular injury, this process induces the local formation of a hemostatic plug, preventing hemorrhage. The hemostatic system in humans presents complex physiological interactions that involve platelets, plasma proteins, endothelial and subendothelial structures. Disequilibrium in the regulatory mechanisms that control the growth and the size of the thrombus is one of the factors that favors the development of diseases related to vascular disorders such as myocardial infarction and stroke, which are among the leading causes of death in the western world. Interfering with platelet function is a strategy for the treatment of thrombotic diseases. Antiplatelet drugs are used mainly in cases related to arterial thrombosis and interfere in the formation of the platelet plug by different mechanisms. Aspirin (acetylsalicylic acid) is the oldest and most widely used antithrombotic drug. Although highly effective in most cases, aspirin has limitations compared to other drugs used in the treatment of homeostatic disorders. For this reason, research related to molecules that interfere with platelet aggregation are of great relevance. In this regard, snake venoms are known to contain a number of molecules that interfere with hemostasis, including platelet function. The mechanisms by which snake venom components inhibit or activate platelet aggregation are varied and can be used as tools for the diagnosis and the treatment of several hemostatic disorders. The aim of this review is to present the role of platelets in hemostasis and the mechanisms by which snake venom toxins interfere with platelet function.

Functional improvement of hemostatic dressing by addition of recombinant batroxobin

Although a number of natural materials have been used as hemostatic agents, many substances do not act quickly enough. Here, we created a novel dressings using collagen and chitosan with recombinant batroxobin (r-Bat) to promote faster and more effective hemostasis. We hypothesized that r-Bat would promote synergetic blood coagulation because it contains a blood coagulation active site different than those of collagen and chitosan. Our results suggest that each substances can maintain hemostatic properties while in the mixed dressings and that our novel hemostatic dressings promotes potent control of bleeding, as demonstrated by a whole blood assay and rat hemorrhage model. In a rat femoral artery model, the scaffold with a high r-Bat concentration more rapidly controlled excessive bleeding. This novel dressings has enormous possible for rapidly controlling bleeding and it improves upon the effect of collagen and chitosan used alone. Our novel r-Bat dressings is a possible candidate for improving preoperative care and displays promising properties as an absorbable agent in hemostasis.

STATEMENT OF SIGNIFICANCE

Despite the excellent hemostatic properties of collagen and chitosan pads, they reported to brittle behavior and lack sufficient hemostatic effect within relevant time. Therefore, we created a novel pad using collagen and chitosan with recombinant batroxobin (r-Bat). r-Bat acts as a thrombin-like enzyme in the coagulation cascade. Specifically, r-Bat, in contrast to thrombin, only splits fibrinopeptide A off and does not influence other hemostatic factors or cells, which makes it clinically useful as a stable hemostatic agent. Also the materials in the pad have synergetic effect because they have different hemostatic mechanisms in the coagulation cascade. This report propose the novel hemostatic pad isreasonable that a great potential for excessive bleeding injury and improve effects of natural substance hemostatic pad.

Antithrombotic activity of Batroxase, a metalloprotease from Bothrops atrox venom, in a model of venous thrombosis

BACKGROUND

Snake venoms are great sources of bioactive molecules, which may be used as models for new drugs. Toxins that interfere in hemostasis have received considerable attention over the years.

OBJECTIVES

This study aimed at the evaluation of the antithrombotic activity of Batroxase, a P-I metalloprotease from Bothrops atrox venom, in an animal model of venous thrombosis.

METHODS

The antithrombotic activity of Batroxase was tested in vivo in a model based on two factors of the Virchow's Triad: blood flow alterations (partial stenosis of the inferior vena cava), and vessel wall injury (10% ferric chloride for 5min), in comparison with sodium heparin (positive control) and saline (negative control). Bleeding/clotting time was assessed by a tail bleeding assay. The immunogenicity of Batroxase was also analyzed.

RESULTS

Batroxase (12mg/kg) reduced thrombus formation in 81%, similarly to heparin (100U/kg), which reduced it in 85% in comparison with the saline group. Both Batroxase and heparin increased bleeding/clotting time in approximately 3 fold. Immunizations of rabbits with Batroxase do not result in detectable levels of antibodies against this metalloprotease.

CONCLUSION

Batroxase presents antithrombotic activity in vivo. Moreover, its lack of immunogenicity increases the interest on its possible therapeutic potential over thrombogenic disorders.

Soluble P-selectin rescues viper venom-induced mortality through anti-inflammatory properties and PSGL-1 pathway-mediated correction of hemostasis

Venomous snakebites are lethal and occur frequently worldwide each year, and receiving the antivenom antibody is currently the most effective treatment. However, the specific antivenom might be unavailable in remote areas. Snakebites by Viperidae usually lead to hemorrhage and mortality if untreated. In the present study, challenges of rattlesnake (Crotalus atrox) venom markedly increased the circulating soluble P-selectin (sP-sel) level, but not P-selectin (P-sel, Selp^−/−) mutants, in wild-type mice. Because sP-sel enhances coagulation through the P-selectin ligand 1 (PSGL-1, Selplg) pathway to produce tissue factor–positive microparticles, we hypothesized that increasing the plasma sP-sel level can be a self-rescue response in hosts against snake venom–mediated suppression of the coagulation system. Confirming our hypothesis, our results indicated that compared with wild-type mice, Selp^−/− and Selplg^−/− mice were more sensitive to rattlesnake venom. Additionally, administration of recombinant sP-sel could effectively reduce the mortality rate of mice challenged with venoms from three other Viperidae snakes. The antivenom property of sP-sel is associated with improved coagulation activity in vivo. Our data suggest that the elevation of endogenous sP-sel level is a self-protective response against venom-suppressed coagulation. The administration of recombinant sP-sel may be developed as a new strategy to treat Viperidae snakebites.

Proteomic Characterization and Comparison of Malaysian Tropidolaemus wagleri and Cryptelytrops purpureomaculatus Venom Using Shotgun-Proteomics

Tropidolaemus wagleri and Cryptelytrops purpureomaculatus are venomous pit viper species commonly found in Malaysia. Tandem mass spectrometry analysis of the crude venoms has detected different proteins in T. wagleri and C. purpureomaculatus. They were classified into 13 venom protein families consisting of enzymatic and nonenzymatic proteins. Enzymatic families detected in T. wagleri and C. purpureomaculatus venom were snake venom metalloproteinase, phospholipase A₂, l-amino acid oxidase, serine proteases, 5′-nucleotidase, phosphodiesterase, and phospholipase B. In addition, glutaminyl cyclotransferase was detected in C. purpureomaculatus. C-type lectin-like proteins were common nonenzymatic components in both species. Waglerin was present and unique to T. wagleri—it was not in C. purpureomaculatus venom. In contrast, cysteine-rich secretory protein, bradykinin-potentiating peptide, and C-type natriuretic peptide were present in C. purpureomaculatus venom. Composition of the venom proteome of T. wagleri and C. purpureomaculatus provides useful information to guide production of effective antivenom and identification of proteins with potential therapeutic applications.

Inhibition of proteases and phospholipases A2 from Bothrops atrox and Crotalus durissus terrificus snake venoms by ascorbic acid, vitamin E, and B-complex vitamins

ABSTRACT The enzyme inhibition by natural and/ or low-cost compounds may represent a valuable adjunct to traditional serotherapy performed in cases of snakebite, mainly with a view to mitigate the local effects of envenoming. The objective of this study was to evaluate possible interactions between vitamins and enzymes that comprise Bothrops atrox and Crotalus durissus terrificus venoms, in vitro. Proteolysis inhibition assays (substrates: azocasein, collagen, gelatin and fibrinogen), hemolysis, coagulation, hemagglutination were carried out using different proportions of vitamins in face of to inhibit minimum effective dose of each venom. The vitamins were responsible for reducing 100% of breaking azocasein by C.d.t. venom, thrombolysis induced by B. atrox and fibrinogenolysis induced by both venoms. It is suggested the presence of interactions between vitamin and the active site of enzymes, for example the interactions between hydrophobic regions present in the enzymes and vitamin E, as well as the inhibitions exercised by antioxidant mechanism.