Snake Venom Peptides: Tools of Biodiscovery

A multiplexing immunosensing platform for the simultaneous detection of snake and scorpion venoms: Towards a better management of antidote administration

Envenomation accidents are usually diagnosed at the hospital through signs and symptoms assessment such as short breath, dizziness and vomiting, numbness, swilling, bruising, or bleeding around the affected site. However, this traditional method provides inaccurate diagnosis given the interface between snakebites and scorpion stings symptoms. Therefore, early determination of bites/stings source would help healthcare professionals select the suitable treatment for patients, thus improving envenomation management. In this study, we developed an innovative multiplexing platform based on dual immunosensors for the simultaneous determination of snake and scorpion venoms using a label-free electrochemical platform. The dual immunosensor was fabricated on graphene/gold nanoparticle modified screen-printed electrodes. The electrodes were first modified with two chemical linkers (cysteamine/phenylene diisothiocyanate) to facilitate the immobilization of the antibodies (antivenoms) through covalent binding. The proposed immunosensor was tested with different venoms that specific to six snake species and two scorpion species. The detection was undergone by monitoring the reduction peak current variation after the venom binding using square wave voltammetry, in presence of ferro/ferricyanide redox system. The dual immunosensor enabled a sensitive and selective simultaneous detection of the snake and scorpion species venoms within wide linear ranges in the limits of detection ranging from 0.057 to 0.027 μg/mL. The applicability of the venoms immunosensor has also been evaluated for the detection of snake and scorpion venoms in human serum samples showing high recovery percentages. These achievements show the great potential of our multiplexing approach for the early detection of snake or scorpion envenomation.

Use of commercial tannic acid against the toxic effects of Bothrops jararacussu venom

Snakebite envenomation is a neglected public health issue affecting thousands of victims worldwide. In Brazil, the genus Bothrops is responsible for 88 % of snakebites; bites from the species B. jararacussu present at a high frequency and are associated with high lethality and morbidity rates. B. jararacussu injects a large volume of venom, leading to massive tissue necrosis, hemorrhage, and eventually death. Antivenom is the only available treatment for neutralizing such toxic effects; it effectively prevents death but not the physical sequelae caused by muscle damage. Antivenom has other drawbacks, such as fever and anaphylactic reactions, high production costs, and the need for controlled storage temperatures. Thus, complementary treatments are sought to overcome these disadvantages of antivenoms. Here, we assessed the effects of commercial tannic acid on the major toxic activities of B. jararacussu venom, such as its proteolytic, plasma coagulation, edematogenic, hemorrhagic, and lethal effects. Overall, the incubation of tannic acid with B. jararacussu venom inhibited the venom's in vitro coagulant and proteolytic effects and in vivo hemorrhagic and edematogenic activities; however, it failed to prevent against lethality. Antibothropic serum protected mice from B. jararacussu venom-induced death and inhibited edema by approximately 45 % but did not protect against hemorrhage. In conclusion, tannic acid efficiently neutralized the main toxic activities of B. jararacussu venom, which causes severe envenomation in some South American countries. Thus, tannic acid is a candidate for managing Bothrops snakebites and, alongside antivenom, may hasten and improve victim recovery.

Metabolomics and proteomics: synergistic tools for understanding snake venom inhibition

Snake envenomation presents a significant global health challenge, especially in rural areas of tropical and subtropical regions. Traditional antivenom therapies face limitations related to efficacy, availability, and specificity, prompting a need for novel approaches. Recent advancements in omics technologies, particularly metabolomics and proteomics, have enhanced our understanding of snake venom composition, toxicity, and potential therapeutic strategies. Metabolomics allows for the study of metabolic changes induced by venom, providing insights into disrupted pathways and possible inhibitors. Proteomics facilitates the identification and characterization of venom proteins, unveiling their interactions with therapeutic agents. Integrative databases such as the Snake Venom Database (SVDB) and STAB Profiles enhance this research by cataloging venom components and aiding in the analysis of venom-antivenom interactions. The combined application of metabolomics and proteomics has led to the identification of crucial metabolic pathways and protein targets essential for effective venom inhibition. This review explores current advances in these fields, emphasizing the role of omics in identifying novel inhibitors and developing next-generation antivenoms. The integrated approach of metabolomics and proteomics offers a comprehensive understanding of snake venom biology, paving the way for more effective and tailored therapeutic solutions for envenomation.

A review on NLRP3 inflammasome modulation by animal venom proteins/peptides: mechanisms and therapeutic insights

The venom peptides from terrestrial as well as aquatic species have demonstrated potential in regulating the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, a sophisticated assemblage present in immune cells responsible for detecting and responding to external mediators. The NLRP3 inflammasome plays a role in several pathological conditions such as type 2 diabetes, hyperglycemia, Alzheimer's disease, obesity, autoimmune disorders, and cardiovascular disorders. Venom peptides derived from animal venoms have been discovered to selectively induce certain signalling pathways, such as the NLRP3 inflammasome, mitogen-activated protein kinase (MAPK), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Experimental evidence has demonstrated that venom peptides can regulate the expression and activation of the NLRP3 inflammasome, resulting in the secretion of pro-inflammatory cytokines including interleukin (IL)-1β and IL-18. Furthermore, these peptides have been discovered to impede the activation of the NLRP3 inflammasome, therefore diminishing inflammation and tissue injury. The functional properties of venom proteins and peptides obtained from snakes, bees, wasps, and scorpions have been thoroughly investigated, specifically targeting the NLRP3 inflammasome pathway, venom proteins and peptides have shown promise as therapeutic agents for the treatment of certain inflammatory disorders. This review discusses the pathophysiology of NLRP3 inflammasome in the onset of various diseases, role of venom as therapeutics. Further, various venom components and their role in the modulation of NLRP3 inflammasome are discoursed. A substantial number of venomous animals and their toxins are yet unexplored, and to comprehensively grasp the mechanisms of action of them and their potential as therapeutic agents, additional research is required which can lead to the development of novel therapeutics.

Peptide Fraction from Naja mandalayensis Snake Venom Showed Neuroprotection Against Oxidative Stress in Hippocampal mHippoE-18 Cells but Not in Neuronal PC12 Cells

Functional characterization of peptide fraction (PF) from snake venom has provided novel opportunities to investigate possible neuroprotective compounds relevant to pharmaceuticals. This study was performed to investigate the PF-mediated neuroprotection obtained from Naja mandalayensis snake venom, a member of the Elapidae family, using two neuronal cell lines, undifferentiated PC12 and differentiated mHippoE-18, in response to H2O2-induced oxidative stress. Cells were pre-treated for 4 h with PF (10, 1, 0.01, and 0.001 μg mL-1), and thereafter exposed to H2O2 (0.5 mmol L-1) for 20 h. Then, the oxidative stress markers and label-free differential proteome strategy were analyzed to understand the neuroprotective effects of PF. In PC12 cells, PF showed no neuroprotective effects against oxidative stress. In mHippoE-18 cells, PF at 0.01 and 0.001 μg mL-1 increased the viability and metabolism of cells against H2O2-induced neurotoxicity, reducing reactive oxygen species (ROS) generation. Interestingly, PF also exhibited a substantial reduction in baseline ROS levels compared to the control, indicating that PF could have compounds with antioxidant features. The comparative proteomic profiling identified 53 proteins with differential expression related to antioxidant action, catalysis, molecular function regulators, structural molecule activity, translation regulatory activity, ATP, and binding. The PF + H2O2 group indicated that protein expression is 6% upregulated, 4% downregulated, and 94% unchanged compared to the H2O2 group. Three significant proteins upregulated in the PF + H2O2 group, including elongation factor 2 (P58252), proteasome subunit alpha type (E9Q0X0), and E2 ubiquitin-conjugating enzyme (A0A338P786), suggested that PF-mediated neuroprotection happens through translational regulation and the degradation of defective proteins via the proteasome complex. Additionally, differential protein expression in PF changed the metabolism, protein synthesis, synaptic activity, and intracellular transport, suggesting that PF contains the rich mixture of bioactive peptides of interest pharmacologically. Overall, this study offers new opportunities for evaluating whether PF's neuroprotective features in specific neuronal cells are maintained and to investigate neurodegenerative disease drug development processes.

Hydrophilic interaction chromatography coupled to high resolution mass spectrometry (HILIC-LC-HRMS): An approach to study natural peptides in Viperidae snake venom

Although proteins in snake venoms have been extensively studied and characterized, low-mass molecules remain relatively unexplored, mainly due to their low abundance, secondary role in envenomation, and some analytical technique limitations. However, these small molecules can provide new important data related to venom toxins' molecular structure, functions, and evolutionary relationships. This research aimed to characterize molecules below 10 kDa in the venoms of snakes from the Viperidae families (Bothrops, Agkistrodon, and Bitis) and compare two chromatographic approaches: reverse-phase chromatography (RP), a classic technique, and hydrophilic interaction liquid chromatography (HILIC), an alternative technique, both coupled with high-resolution mass spectrometry (HRMS). The results showed that the separation of the HILIC column provided a more efficient evenly distributed ion profile than RP, contributing to a 25.6% increase in the sequences identified. Homologous sequences for Bradykinin-potentiating peptides (BPPs) and fragments of major venom proteins, possibly cryptids, were found. In addition, BPP 13a, peptides rich in histidine and glycine (pHpG), and spacer sequences were identified in all snakes analyzed, especially with HILIC separation, suggesting that these sequences may be conserved within Viperidae. These findings indicate that the use of the HILIC column, compared to RP, is a promising approach for characterizing peptides in snake venom obtained by the ultrafiltration process. It contributes to the study of these still poorly understood molecules and is also a good option for studying other complex protein/peptide mixtures.

Emerging Trends in Snake Venom-Loaded Nanobiosystems for Advanced Medical Applications: A Comprehensive Overview

Advances in medical nanobiotechnology have notably enhanced the application of snake venom toxins, facilitating the development of new therapies with animal-derived toxins. The vast diversity of snake species and their venom complexities underline the need for ongoing research. This review is dedicated to exploring the integration of snake venom with nanoparticles to enable their use in human therapies aiming to develop treatments. The complex mixture of snake venom not only inflicts significant pathological effects but also offers valuable insights for the creation of innovative therapies, particularly in the realm of nanobiotechnology. Nanoscale encapsulation not only mitigates the inherent toxicity of snake venom but also amplifies their antitumoral, antimicrobial, and immunomodulatory properties. The synergy between venom-derived macromolecules and nanotechnology offers a novel pathway for augmenting the efficacy and safety of conventional antivenom therapies, extending their applicability beyond treating bites to potentially addressing a myriad of health issues. In conclusion, nanotechnology presents a compelling therapeutic frontier that promises to improve current treatment modalities and ameliorate the adverse effects associated with venomous snakebites.

A review on inflammation modulating venom proteins/peptide therapeutics and their delivery strategies: A review

Inflammation is an initial biological reaction that occurs in response to infection caused by foreign pathogens or injury. This process involves a tightly controlled series of signaling events at the molecular and cellular levels, with the ultimate goal of restoring tissue balance and protecting against invading pathogens. Malfunction in the process of inflammation can result in a diverse array of diseases, such as cardiovascular, neurological, and autoimmune disorders. Therefore, the management of inflammation is of utmost importance in modern medicine. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids have long been the mainstays of pharmacological treatment for inflammation, effectively alleviating symptoms in many patients. Recently, toxins and venom, formerly seen as mostly harmful to the human body, have been recognized as possible medicinal substances for treating inflammation. Organisms that are venomous, such as spiders, scorpions, snakes, and certain marine species, have developed a wide range of powerful toxins that can effectively disable or discourage predators. Remarkably, the majority of these poisons and venoms consist of proteins and peptides, which are acknowledged as significant bioactive compounds with medicinal potential. The goal of this review is to investigate the medicinal potential of peptides derived from venoms and their complex mechanism of action in suppressing inflammation. This review also discusses various challenges and future prospects for effective venom delivery.

The Venom of Vipera ammodytes ammodytes: Proteomics, Neurotoxic Effect and Neutralization by Antivenom

Deep proteomic analyses identified, in total, 159 master proteins (with 1% FDR and 2 unique peptides) from 26 protein families in the venom of Vipera ammodytes ammodytes (Vaa). Data are available via ProteomeXchange with the identifier PXD056495. The relative abundance of PLA2s is 11.60% of the crude venom, of which 4.35% are neurotoxic Ammodytoxins (Atxs). The neurotoxicity of the venom of Vaa and the neutralizing effect of the antivenom were tested on the neuromuscular preparation of the diaphragm (NPD) of rats. The activity of PLA2 in the venom of Vaa and its neutralization by the antivenom were determined under in vitro conditions. The Vaa venom leads to a progressive decrease in NPD contractions. We administered pre-incubated venom/antivenom mixtures at various ratios of 1:2, 1:10 and 1:20 (w/w) and observed the effects of these mixtures on NPD contractions. The results show that the mean effective time (ET50) for NPD contractions with the 1:20 mixture is highly significantly different (p < 0.001) from the ET50 for the venom and the ET50 for the 1:2 and 1:10 mixture ratios. We also found a highly significant (p < 0.001) reduction in Na+/K+-ATPase activity in the NPD under the influence of the venom. The reduction in the activity of this enzyme was reversible by the antivenom. Under in vitro conditions, we have achieved the complete neutralization of PLA2 by the antivenom. In conclusion, the antivenom abolished the venom-induced progressive decrease in NPD contractions in a concentration-dependent manner. Antivenom with approximately the same mass proportion almost completely restores Na+/K+-ATPase activity in the NPD and completely neutralizes the PLA2 activity of the venom in vitro.

Proteomic Profiling of Venoms from Bungarus suzhenae and B. bungaroides: Enzymatic Activities and Toxicity Assessment

Kraits are venomous snakes of the genus Bungarus from the family Elapidae. Their venom typically demonstrates neurotoxicity; however, the toxicity is significantly influenced by the snake's species and geographical origin. Among the Bungarus species, Bungarus suzhenae and B. bungaroides have been poorly studied, with little to no information available regarding their venom composition. In this study, a proteomic approach was employed using LC-MS/MS to identify proteins from trypsin-digested peptides. The analysis revealed 102 venom-related proteins from 18 distinct functional protein families in the venom of B. suzhenae, with the primary components being three-finger toxins (3-FTx, 25.84%), phospholipase A2 (PLA2, 40.29%), L-amino acid oxidase (LAAO, 10.33%), Kunitz-type serine protease inhibitors (KUN, 9.48%), and snake venom metalloproteinases (SVMPs, 6.13%). In the venom of B. bungaroides, 99 proteins from 17 families were identified, with primary components being 3-FTx (33.87%), PLA2 (37.91%), LAAO (4.21%), and KUN (16.60%). Enzymatic activity assays confirmed the presence of key venom enzymes. Additionally, the LD50 values for B. suzhenae and B. bungaroides were 0.0133 μg/g and 0.752 μg/g, respectively, providing a reference for toxicity studies of these two species. This research elucidates the proteomic differences in the venoms of these two species, offering a foundation for developing antivenoms and clinical treatments for envenomation.

Proteomic diversity of Russell's viper venom: exploring PLA2 isoforms, pharmacological effects, and inhibitory approaches

Snakebite envenomation is a serious health concern in tropical regions, resulting in high mortality. The World Health Organization (WHO) has declared it a neglected tropical disease and is working on strategies to reduce mortality. Russell's viper (Daboia russelii) is one of the most abundant venomous snakes found across Southeast Asia. Proteomic analysis of Russell's viper venom has demonstrated variation, with phospholipase A2 (PLA2) being the most abundant toxin across geographic boundaries. PLA2, a major constituent of the low-molecular-weight fraction of snake venom, hydrolyses phospholipids at the sn-2 position, releasing arachidonic acid and lysophospholipids. They are reported to cause various pharmacological effects, including hemolysis, anticoagulation, neurotoxicity, myotoxicity, and oedema. Though administration of antivenoms (ASV) is the primary treatment for envenomation, it has many drawbacks. Besides causing hypersensitivity reactions and life-threatening anaphylaxis, treatment with ASV is further complicated due to its inability to neutralize low-molecular-weight toxins. Thus, there is a greater need to produce next-generation antivenoms that can target specific toxins in the venom. In this review, we explored the classification of Russell's viper and the variation in its proteomic profile across Southeast Asia to date. In addition, we have also summarized the mechanism of action of PLA2 and discussed various isoforms of PLA2 found across different regions with their respective pharmacological effects. Finally, the drawbacks of commercially available antivenoms and the molecules investigated for inhibiting the low-molecular-weight toxin, PLA2 are discussed.

Venom-derived peptides for breaking through the glass ceiling of drug development

Venoms are complex mixtures produced by animals and consist of hundreds of components including small molecules, peptides, and enzymes selected for effectiveness and efficacy over millions of years of evolution. With the development of venomics, which combines genomics, transcriptomics, and proteomics to study animal venoms and their effects deeply, researchers have identified molecules that selectively and effectively act against membrane targets, such as ion channels and G protein-coupled receptors. Due to their remarkable physico-chemical properties, these molecules represent a credible source of new lead compounds. Today, not less than 11 approved venom-derived drugs are on the market. In this review, we aimed to highlight the advances in the use of venom peptides in the treatment of diseases such as neurological disorders, cardiovascular diseases, or cancer. We report on the origin and activity of the peptides already approved and provide a comprehensive overview of those still in development.

Venomics and Peptidomics of Palearctic Vipers: A Clade-Wide Analysis of Seven Taxa of the Genera Vipera, Montivipera, Macrovipera, and Daboia across Türkiye

Snake venom variations are a crucial factor to understand the consequences of snakebite envenoming worldwide, and therefore it is important to know about toxin composition alterations between taxa. Palearctic vipers of the genera Vipera, Montivipera, Macrovipera, and Daboia have high medical impacts across the Old World. One hotspot for their occurrence and diversity is Türkiye, located on the border between continents, but many of their venoms remain still understudied. Here, we present the venom compositions of seven Turkish viper taxa. By complementary mass spectrometry-based bottom-up and top-down workflows, the venom profiles were investigated on proteomics and peptidomics level. This study includes the first venom descriptions of Vipera berus barani, Vipera darevskii, Montivipera bulgardaghica albizona, and Montivipera xanthina, as well as the first snake venomics profiles of Turkish Macrovipera lebetinus obtusa, and Daboia palaestinae, including an in-depth reanalysis of M. bulgardaghica bulgardaghica venom. Additionally, we identified the modular consensus sequence pEXW(PZ)1-2P(EI)/(KV)PPLE for bradykinin-potentiating peptides in viper venoms. For better insights into variations and potential impacts of medical significance, the venoms were compared against other Palearctic viper proteomes, including the first genus-wide Montivipera venom comparison. This will help the risk assessment of snakebite envenoming by these vipers and aid in predicting the venoms' pathophysiology and clinical treatments.

Structural, Biochemical Characterization and Molecular Mechanism of Cerastokunin: A New Kunitz-Type Peptide with Potential Inhibition of Thrombin, Factor Xa and Platelets

The current investigation focused on separating Cerastes cerastes venom to produce the first Kunitz-type peptide. Based on its anti-trypsin effect, Cerastokunin, a 7.75 kDa peptide, was purified until homogenity by three steps of chromatography. Cerastokunin was found to include 67 amino acid residues that were obtained by de novo sequencing using LC-MALDI-MSMS. Upon alignment with Kunitz-type peptides, there was a high degree of similarity. Cerastokunin's 3D structure had 12% α-helices and 21% β-strands with pI 8.48. Cerastokunin showed a potent anticoagulant effect by inhibiting the protease activity of thrombin and trypsin as well as blocking the intrinsic and extrinsic coagulation pathways. In both PT and aPPT, Cerastokunin increased the blood clotting time in a dose-dependent way. Using Lys48 and Gln192 for direct binding, Cerastokunin inhibited thrombin, Factor Xa and trypsin as shown by molecular docking. Cerastokunin exhibited a dose-response blockade of PARs-dependent pathway platelet once stimulated by thrombin. An increased concentration of Cerastokunin resulted in a larger decrease of tail thrombus in the mice-carrageenan model in an in vivo investigation when compared to the effects of antithrombotic medications. At all Cerastokunin doses up to 6 mg/kg, no in vivo toxicity was seen in challenged mice over the trial's duration.

Fraction of C. d. collilineatus venom containing crotapotin protects PC12 cells against MPP + toxicity by activating the NGF-signaling pathway

Background

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease. There is no effective treatment for neurodegenerative diseases. Snake venoms are a cocktail of proteins and peptides with great therapeutic potential and might be useful in the treatment of neurodegenerative diseases. Crotapotin is the acid chain of crotoxin, the major component of Crotalus durissus collilineatus venom. PD is characterized by low levels of neurotrophins, and synaptic and axonal degeneration; therefore, neurotrophic compounds might delay the progression of PD. The neurotrophic potential of crotapotin has not been studied yet.

Methods

We evaluated the neurotrophic potential of crotapotin in untreated PC12 cells, by assessing the induction of neurite outgrowth. The activation of the NGF signaling pathway was investigated through pharmacological inhibition of its main modulators. Additionally, its neuroprotective and neurorestorative effects were evaluated by assessing neurite outgrowth and cell viability in PC12 cells treated with the dopaminergic neurotoxin MPP+ (1-methyl-4-phenylpyridinium), known to induce Parkinsonism in humans and animal models.

Results

Crotapotin induced neuritogenesis in PC12 cells through the NGF-signaling pathway, more specifically, by activating the NGF-selective receptor trkA, and the PI3K/Akt and the MAPK/ERK cascades, which are involved in neuronal survival and differentiation. In addition, crotapotin had no cytotoxic effect and protected PC12 cells against the inhibitory effects of MPP+ on cell viability and differentiation.

Conclusion

These findings show, for the first time, that crotapotin has neurotrophic/neuroprotective/neurorestorative potential and might be beneficial in Parkinson's disease. Additional studies are necessary to evaluate the toxicity of crotapotin in other cell models.

Atrase A, a P-III class metalloproteinase purified from cobra venom, exhibits potent anticoagulant activity by inhibiting coagulation pathway and activating the fibrinolytic system

Snake venoms, comprising a complex array of protein-rich components, an important part of which are snake venom metalloproteinases (SVMPs). These SVMPs, which are predominantly isolated from viperid venoms, are integral to the pathology of snakebites. However, SVMPs derived from elapid venoms have not been extensively explored, and only a handful of SVMPs have been characterized to date. Atrase A, a nonhemorrhagic P-III class metalloproteinase from Naja atra venom, exhibits weak proteolytic activity against fibrinogen in vitro but has pronounced anticoagulant effects in vivo. This contrast spurred investigations into its anticoagulant mechanisms. Research findings indicate that atrase A notably extends the activated partial thromboplastin time, diminishes fibrinogen levels, and impedes platelet aggregation. The anticoagulant action of atrase A primarily involves inhibiting coagulation factor VIII and activating the endogenous fibrinolytic system, which in turn lowers fibrinogen levels. Additionally, its effect on platelet aggregation further contributes to its anticoagulant profile. This study unveils a novel anticoagulant mechanism of atrase A, significantly enriching the understanding of the roles of cobra venom metalloproteinases in snake venom. Furthermore, these findings underscore the potential of atrase A as a novel anticoagulant drug, offering insights into the functional evolutions of cobra venom metalloproteinases.

Maggot Kinase and Natural Thrombolytic Proteins

Thrombolytic enzymes constitute a class of proteases with antithrombotic functions. Derived from natural products and abundant in nature, certain thrombolytic enzymes, such as urokinase, earthworm kinase, and streptokinase, have been widely used in the clinical treatment of vascular embolic diseases. Fly maggots, characterized by their easy growth and low cost, are a traditional Chinese medicine recorded in the Compendium of Materia Medica. These maggots can also be used as raw material for the extraction and preparation of thrombolytic enzymes (maggot kinase). In this review, we assembled global research reports on natural thrombolytic enzymes through a literature search and reviewed the functions and structures of natural thrombolytic enzymes to provide a reference for natural thrombophilic drug screening and development.

Unveiling Novel Kunitz- and Waprin-Type Toxins in the Micrurus mipartitus Coral Snake Venom Gland: An In Silico Transcriptome Analysis

Kunitz-type peptide expression has been described in the venom of snakes of the Viperidae, Elapidae and Colubridae families. This work aimed to identify these peptides in the venom gland transcriptome of the coral snake Micrurus mipartitus. Transcriptomic analysis revealed a high diversity of venom-associated Kunitz serine protease inhibitor proteins (KSPIs). A total of eight copies of KSPIs were predicted and grouped into four distinctive types, including short KSPI, long KSPI, Kunitz-Waprin (Ku-WAP) proteins, and a multi-domain Kunitz-type protein. From these, one short KSPI showed high identity with Micrurus tener and Austrelaps superbus. The long KSPI group exhibited similarity within the Micrurus genus and showed homology with various elapid snakes and even with the colubrid Pantherophis guttatus. A third group suggested the presence of Kunitz domains in addition to a whey-acidic-protein-type four-disulfide core domain. Finally, the fourth group corresponded to a transcript copy with a putative 511 amino acid protein, formerly annotated as KSPI, which UniProt classified as SPINT1. In conclusion, this study showed the diversity of Kunitz-type proteins expressed in the venom gland transcriptome of M. mipartitus.

Identification of Potential Insulinotropic Cytotoxins from Indian Cobra Snake Venom Using High-Resolution Mass Spectrometry and Analyzing Their Possible Interactions with Potassium Channel Receptors by In Silico Studies

Snake venoms are a potential source of bioactive peptides, which have multiple therapeutic properties in treating diseases such as diabetes, cancer, and neurological disorders. Among bioactive peptides, cytotoxins (CTXs) and neurotoxins are low molecular weight proteins belonging to the three-finger-fold toxins (3FTxs) family composed of two β sheets that are stabilized by four to five conserved disulfide bonds containing 58-72 amino acid residues. These are highly abundant in snake venom and are predicted to have insulinotropic activities. In this study, the CTXs were purified from Indian cobra snake venom using preparative HPLC and characterized using high-resolution mass spectrometry (HRMS) TOF-MS/MS. Further SDS-PAGE analysis confirmed the presence of low molecular weight cytotoxic proteins. The CTXs in fractions A and B exhibited dose-dependent insulinotropic activity from 0.001 to 10 µM using rat pancreatic beta-cell lines (RIN-5F) in the ELISA. Nateglinide and repaglinide are synthetic small-molecule drugs that control sugar levels in the blood in type 2 diabetes, which were used as a positive control in ELISA. Concluded that purified CTXs have insulinotropic activity, and there is a scope to use these proteins as small molecules to stimulate insulinotropic activities. At this stage, the focus is on the efficiency of the cytotoxins to induce insulin. Additional work is ongoing on animal models to see the extent of the beneficial effects and efficiency to cure diabetes using streptozotocin-induced models.

Recombinant human scFv antibody fragments against phospholipase A2 from Naja naja and Echis carinatus snake venoms: In vivo neutralization and mechanistic insights

Snake envenomation results in a range of clinical sequelae, and widely used animal-based conventional antivenoms exhibit several limitations including the adverse immunological effects in human snake bite victims. Therefore, human monoclonal anti-snake venom antibodies or fragments can be an alternate therapy for overcoming the existing limitations. We developed venom-neutralizing humanized scFv antibodies and analyzed biochemical mechanisms associated with the inhibition of toxicity. Tomlinson I and J human scFv antibody libraries were screened against Naja naja and Echis carinatus venoms, and seven unique scFv antibodies were obtained. Further, specific toxins of snake venom interacting with each of these scFvs were identified, and phospholipase A2 (PLA2) was found to be prominently captured by the phage-anchored scFv antibodies. Our study indicated PLA2 to be one of the abundant toxins in Naja naja and Echis carinatus venom samples. The scFvs binding to PLA2 were used to perform in vivo survival assay using the mouse model and in vitro toxin inhibition assays. scFv N194, which binds to acidic PLA2, protected 50% of mice treated with Naja naja venom. Significant prolongation of survival time and 16% survival were observed in Echis carinatus venom-challenged mice treated with scFv E113 and scFv E10, respectively. However, a combination comprised of an equal amount of two scFvs, E113 and E10, both interacting with basic PLA2, exhibited synergistically enhanced survival of 33% in Echis carinatus venom-challenged mice. No such synergistically enhanced survival was observed in the case of combinatorial treatment with anti-Naja naja scFvs, N194, and N248. These scFvs demonstrated partial inhibition of venom-induced myotoxicity, and E113 also inhibited hemolysis by 50%, which corroborates the enhanced survival during combinatorial treatment in Echis carinatus venom-challenged mice.

A Review of Rattlesnake Venoms

Venom components are invaluable in biomedical research owing to their specificity and potency. Many of these components exist in two genera of rattlesnakes, Crotalus and Sistrurus, with high toxicity and proteolytic activity variation. This review focuses on venom components within rattlesnakes, and offers a comparison and itemized list of factors dictating venom composition, as well as presenting their known characteristics, activities, and significant applications in biosciences. There are 64 families and subfamilies of proteins present in Crotalus and Sistrurus venom. Snake venom serine proteases (SVSP), snake venom metalloproteases (SVMP), and phospholipases A2 (PLA2) are the standard components in Crotalus and Sistrurus venom. Through this review, we highlight gaps in the knowledge of rattlesnake venom; there needs to be more information on the venom composition of three Crotalus species and one Sistrurus subspecies. We discuss the activity and importance of both major and minor components in biomedical research and drug development.

A secreted BPTI/Kunitz inhibitor domain-containing protein of barber's pole worm interacts with host NLRP3 inflammasome activation-associated G protein subunit to inhibit IL-1β and IL-18 maturation in vitro

Protease inhibitors are major components of excretory/secretory products released by parasitic nematodes and have been proposed to play roles in host-parasite interactions. Haemonchus contortus (the barber's pole worm) encodes for several serine protease inhibitors, and in a previous study we identified a trypsin inhibitor-like serine protease inhibitor of this blood-feeding nematode, SPI-I8, as necessary for anticoagulation. Here, we demonstrated that a bovine pancreatic trypsin inhibitor/Kunitz-type serine protease inhibitor (BPTI/Kunitz) domain-containing protein highly expressed in parasitic stages, HCON_00133150, is involved in suppressing proinflammatory cytokine production in mammalian cells. Fluorescent labelling of HCON_00133150 revealed a punctate localisation at the inner hypodermal membrane of H. contortus, an organ closely related to the excretory column. Yeast two-hybrid screening and immunoprecipitation-mass spectrometry identified that the recombinant HCON_00133150 physically interacted with a range of host proteins including the G protein subunit beta 1 of sheep (Ovis aries; OaGNB1), a negative regulator of NLRP3 inflammasome activation. Interestingly, heterologous expression of HCON_00133150 enhanced the inhibitory effect of OaGNB1 on NLRP3 inflammasome and the maturation of proinflammatory cytokines IL-1β and IL-18 in transfected cells. 1-to-1 orthologues (n = 33) of BPTI/Kunitz inhibitor domain-containing proteins were predicted in clades III, IV and V (but not clade I) parasitic nematodes. Structural (tandem BPTI/Kunitz inhibitor domains inverted into the globular reticulation) and functional (a GNB1 enhancer) characterisation of HCON_00133150 and its orthologues elucidated that these molecules might contribute to immune suppression by parasitic nematodes in animals and humans.

Isolation and characterization of ZK002, a novel dual function snake venom protein from Deinagkistrodon acutus with anti-angiogenic and anti-inflammatory properties

Introduction: Pathological angiogenesis, the abnormal or excessive generation of blood vessels, plays an important role in many diseases including cancer, diabetic retinopathy, psoriasis, and arthritis. Additionally, increasing evidence supports the close linkage between angiogenesis and inflammation. Snake venoms are a rich natural source of biologically active molecules and carry rich potential for the discovery of anti-angiogenic and anti-inflammatory modulators. Methods: Here, we isolated and purified a novel protein, ZK002, from the venom of the snake Deinagkistrodon acutus, and investigated its anti-angiogenic and anti-inflammatory activities and mechanisms. Results: ZK002 was identified as a 30 kDa heterodimeric protein of α and β chains, which exhibited anti-angiogenic activity in various in vitro assays. Mechanistically, ZK002 inhibited activation of VEGF signaling and related mediators including eNOS, p38, LIMK, and HSP27. ZK002 also upregulated the metalloproteinase inhibitor TIMP3 and inhibited components of the VEGF-induced signaling cascade, PPP3R2 and SH2D2A. The anti-angiogenic activity of ZK002 was confirmed in multiple in vivo models. ZK002 could also inhibit the in vitro expression of pro-inflammatory cytokines, as well as in vivo inflammation in the carrageenin-induced edema rat model. Conclusion: Our findings highlight the potential for further development of ZK002 as a dual function therapeutic against diseases with involvement of pathogenic angiogenesis and chronic inflammation.

Snake venom disintegrins update: insights about new findings

Snake venom disintegrins are low molecular weight, non-enzymatic proteins rich in cysteine, present in the venom of snakes from the families Viperidae, Crotalidae, Atractaspididae, Elapidae, and Colubridae. This family of proteins originated in venom through the proteolytic processing of metalloproteinases (SVMPs), which, in turn, evolved from a gene encoding an A Disintegrin And Metalloprotease (ADAM) molecule. Disintegrins have a recognition motif for integrins in their structure, allowing interaction with these transmembrane adhesion receptors and preventing their binding to proteins in the extracellular matrix and other cells. This interaction gives disintegrins their wide range of biological functions, including inhibition of platelet aggregation and antitumor activity. As a result, many studies have been conducted in an attempt to use these natural compounds as a basis for developing therapies for the treatment of various diseases. Furthermore, the FDA has approved Tirofiban and Eptifibatide as antiplatelet compounds, and they are synthesized from the structure of echistatin and barbourin, respectively. In this review, we discuss some of the main functional and structural characteristics of this class of proteins and their potential for therapeutic use.

Unlocking the potential of snake venom-based molecules against the malaria, Chagas disease, and leishmaniasis triad

Malaria, leishmaniasis and Chagas disease are vector-borne protozoal infections with a disproportionately high impact on the most fragile societies in the world, and despite malaria-focused research gained momentum in the past two decades, both trypanosomiases and leishmaniases remain neglected tropical diseases. Affordable effective drugs remain the mainstay of tackling this burden, but toxicicty, inneficiency against later stage disease, and drug resistance issues are serious shortcomings. One strategy to overcome these hurdles is to get new therapeutics or inspiration in nature. Indeed, snake venoms have been recognized as valuable sources of biomacromolecules, like peptides and proteins, with antiprotozoal activity. This review highlights major snake venom components active against at least one of the three aforementioned diseases, which include phospholipases A2, metalloproteases, L-amino acid oxidases, lectins, and oligopeptides. The relevance of this repertoire of biomacromolecules and the bottlenecks in their clinical translation are discussed considering approaches that should increase the success rate in this arduous task. Overall, this review underlines how venom-derived biomacromolecules could lead to pioneering antiprotozoal treatments and how the drug landscape for neglected diseases may be revolutionized by a closer look at venoms. Further investigations on poorly studied venoms is needed and could add new therapeutics to the pipeline.

Exploring Toxin Genes of Myanmar Russell's Viper, Daboia siamensis, through De Novo Venom Gland Transcriptomics

The Russell's viper (Daboia siamensis) is a medically important venomous snake in Myanmar. Next-generation sequencing (NGS) shows potential to investigate the venom complexity, giving deeper insights into snakebite pathogenesis and possible drug discoveries. mRNA from venom gland tissue was extracted and sequenced on the Illumina HiSeq platform and de novo assembled by Trinity. The candidate toxin genes were identified via the Venomix pipeline. Protein sequences of identified toxin candidates were compared with the previously described venom proteins using Clustal Omega to assess the positional homology among candidates. Candidate venom transcripts were classified into 23 toxin gene families including 53 unique full-length transcripts. C-type lectins (CTLs) were the most highly expressed, followed by Kunitz-type serine protease inhibitors, disintegrins and Bradykinin potentiating peptide/C-type natriuretic peptide (BPP-CNP) precursors. Phospholipase A₂, snake venom serine proteases, metalloproteinases, vascular endothelial growth factors, L-amino acid oxidases and cysteine-rich secretory proteins were under-represented within the transcriptomes. Several isoforms of transcripts which had not been previously reported in this species were discovered and described. Myanmar Russell's viper venom glands displayed unique sex-specific transcriptome profiles which were correlated with clinical manifestation of envenoming. Our results show that NGS is a useful tool to comprehensively examine understudied venomous snakes.

Therapeutic applications of snake venoms: An invaluable potential of new drug candidates

Animal venoms and their chemical compounds have aroused both empirical and scientific attention for ages. However, there has been a significant increase in scientific investigations in recent decades, allowing the production of various formulations that are helping in the development of many important tools for biotechnological, diagnostic, or therapeutic use, both in human and animal health, as well as in plants. Venoms are composed of biomolecules and inorganic compounds that may have physiological and pharmacological activities that are not related to their principal actions (prey immobilization, digestion, and defense). Snake venom toxins, mainly enzymatic and non-enzymatic proteins, and peptides have been identified as potential prototypes for new drugs and/or models for the development of pharmacologically active structural domains for the treatment of cancer, cardiovascular diseases, neurodegenerative and autoimmune diseases, pain, and infectious-parasitic diseases. This minireview aims to provide an overview of the biotechnological potential of animal venoms, with a focus on snakes, and to introduce the reader to the fascinating world of Applied Toxinology, where animal biodiversity can be used to develop therapeutic and diagnostic applications for humans.

Peptidomics

Peptides are biopolymers, typically consisting of 2-50 amino acids. They are biologically produced by the cellular ribosomal machinery or by non-ribosomal enzymes and, sometimes, other dedicated ligases. Peptides are arranged as linear chains or cycles, and include post-translational modifications, unusual amino acids and stabilizing motifs. Their structure and molecular size render them a unique chemical space, between small molecules and larger proteins. Peptides have important physiological functions as intrinsic signalling molecules, such as neuropeptides and peptide hormones, for cellular or interspecies communication, as toxins to catch prey or as defence molecules to fend off enemies and microorganisms. Clinically, they are gaining popularity as biomarkers or innovative therapeutics; to date there are more than 60 peptide drugs approved and more than 150 in clinical development. The emerging field of peptidomics comprises the comprehensive qualitative and quantitative analysis of the suite of peptides in a biological sample (endogenously produced, or exogenously administered as drugs). Peptidomics employs techniques of genomics, modern proteomics, state-of-the-art analytical chemistry and innovative computational biology, with a specialized set of tools. The complex biological matrices and often low abundance of analytes typically examined in peptidomics experiments require optimized sample preparation and isolation, including in silico analysis. This Primer covers the combination of techniques and workflows needed for peptide discovery and characterization and provides an overview of various biological and clinical applications of peptidomics.

[Analysis and identification of suspected snake venom samples using nano-ultra-high performance liquid chromatography-high resolution mass spectrometry]

Snake venom is a complex mixture secreted from the glands of poisonous snakes， which contains proteins， peptides， lipids， nucleosides， sugars， amino acids， amines， metal ions， and other components. According to the toxicological classification， snake venoms can be classified as neurotoxins， anticoagulants and procoagulant toxins， cardiac toxins， other toxin proteins， and enzymes. Proteins and peptides are the key components of snake venom. The establishment of rapid， accurate analysis and identification methods for proteins in snake venom is a prerequisite for snake venom-related forensic identification， intoxication events， and pharmaceutical development. Until now， the classical analysis and identification methods have mainly been biochemical or immunoassays for DNA or proteins， such as polymerase chain reaction， agglutination test， enzyme-linked immunosorbent assay， fluorescent immunoassay， and various biosensing approaches. These methods have some limitations such as a high false-positive ratio， low sensitivity， poor anti-interference ability， and limited species discrimination capability. In recent years， with the rapid development of mass spectrometry （MS） techniques， the proteomics of snake venom has also attracted much attention and has contributed to the identification of snake species， in which non-targeted and targeted proteomics represent two main divisions. However， species identification via proteomics is in its infancy in forensic science. First， the tandem MS spectra of peptide sequences are highly complex， which poses a great challenge for the strict and accurate matching of peptides based on the rational speculation of MS fragmentation rules and theoretical calculations in non-targeted proteomics. Second， for the confirmation and identification of unknown substances， reference substances are commonly needed， but those for snake venom are lacking. Proteomics in snake venom identification is still in progress to improve the identification confidence and clarify the identification rules. In this work， a method based on nano-ultra-high performance liquid chromatography-quadrupole-orbitrap high-resolution mass spectrometry （Nano LC-MS/HRMS） and size exclusion chromatography （SEC） was developed for identifying proteins and their source species， with strict rules for five suspected snake venom samples and their contamination in one case. Three SEC elution peaks were obtained from each of the five samples， which were lyophilized and treated with trypsin in solution， and then separated and analyzed by Nano LC-MS/HRMS. First， the Full MS/dd MS² mode was used for the non-targeted acquisition of peptide information in the samples， and after submission to the Swiss-Prot database， the protein databases of Serpentes， Colubroidea， Elapidae， Elapinae， and Naja were contracted stepwise and compared. A total of 32 proteins from Naja atra were identified under the conditions of both peptide spectrum match and false discovery rate less than 1%， and number of characteristic peptides greater than or equal to two. All of these were derived from ten families of Naja atra， mainly three-finger toxins， metalloproteinases， and phospholipase A2. Proteins D3TTC2， D5LMJ3， Q7T1K6， Q9DEQ3， and Q9YGI4 were the most common among the five samples. Finally， the parallel reaction monitoring mode was adopted to select two unique peptides for each protein for targeted verification. It was considered that a protein in the samples was truly identified when it met the strict standard "the Δm/z of at least 75% y⁺ and b⁺ ions of each unique peptide was less than 5 ppm". After these consequently procedures， we identified that all five samples contained the venom of the Naja atra. Our identification method is a systematic and strict example that can provide effective technical support for the forensic identification of snake venom poisoning， as well as for pharmaceutical development toward snake venoms.

The secretory phenotypes of envenomed cells: Insights into venom cytotoxicity

Snake envenomation is listed as Category A Neglected Tropical Diseases (NTD) by World Health Organization, indicates a severe public health problem. The global figures for envenomation cases are estimated to be more than 1.8 million annually. Even if the affected victims survive the envenomation, they might suffer from permanent morbidity due to local envenomation. One of the most prominent local envenomation is dermonecrosis. Dermonecrosis is a pathophysiological outcome of envenomation that often causes disability in the victims due to surgical amputations, deformities, contracture, and chronic ulceration. The key venom toxins associated with this local symptom are mainly attributed to substantial levels of enzymatic and non-enzymatic toxins as well as their possible synergistic actions. Despite so, the severity of the local tissue damage is based on macroscopic observation of the bite areas. Furthermore, limited knowledge is known about the key biomarkers involved in the pathogenesis of dermonecrosis. The current immunotherapy with antivenom is also ineffective against dermonecrosis. These local effects eventually end up as sequelae. There is also a global shortage of toxins-targeted therapeutics attributed to inadequate knowledge of the actual molecular mechanisms of cytotoxicity. This chapter discusses the characterization of secretory phenotypes of dermonecrosis as an advanced tool to indicate its severity and pathogenesis in envenomation. Altogether, the secretory phenotypes of envenomed cells and tissues represent the precise characteristics of dermonecrosis caused by venom toxins.

Identification evidence unraveled by strict proteomics rules toward forensic samples

Snake venom is a complex mixture of proteins and peptides secreted by venomous snakes from their poison glands. Although proteomics for snake venom composition, interspecific differences, and developmental evolution has been developed for a decade, current diagnosis or identification techniques of snake venom in clinical intoxication and forensic science applications are mainly dependent on morphological and immunoassay. It could be expected that the proteomics techniques directly offer great help. This work applied a bottom-up proteomics method to identify proteins' types and species attribution in suspected snake venom samples using ultrahigh-performance liquid chromatography-quadrupole-electrostatic field Orbitrap tandem mass spectrometric technique, and cytotoxicity assay was amended to provide a direct evidence of toxicity. Toward the suspicious samples seized in the security control, sample pretreatment (in-sol and in-gel digestion) and data acquisition (nontargeted and targeted screening) modes complemented and validated each other. We have implemented two consequent approaches in identifying the species source of proteins in the samples via the points of venom proteomics and strict forensic identification. First, we completed a workflow consisting of a proteomics database match toward an entire SWISS-PROT (date 2018-11-22) database and a result-directed specific taxonomy database. The latter was a helpful hint to compare master protein kinds and reveal the insufficiency of specific venom proteomics characterization rules. Second, we suggested strict rules for protein identification to meet the requirements of forensic science on improved identification correctness, that is, (1) peptide spectrum matches confidence, peptide confidence, and protein confidence were both high (with the false-discovery ratio less than 1%); (2) the number of unique peptides was more than or equal to two in one protein, and (3) within unique peptides, which at least 75% of the ∆m/z of the matched y and b ions were less than 5 ppm. We identified these samples as cobra venom containing 10 highly abundant proteins (P00597, P82463, P60770, Q9YGI4, P62375, P49123, P80245, P60302, P01442, and P60304) from two snake venom protein families (acid phospholipase A2 and three-finger toxins), and the most abundant proteins were cytotoxins.

A rational in silico approach to identify inhibitors of Batroxrhagin from Bothrops atrox

Bothrops atrox venom comprises several types of bioactive molecules, enzymatic and non-enzymatic, among those, Batroxrhagin is the most predominant SVMP P-III enzyme, which are responsible for induction of local and systemic hemorrhage and muscle fibers damage, impairing regeneration. Due to great difficulties in establishing an antibothropic drug, new strategies must be addressed to achieve a more effective and efficient treatment. There are no studies of specific catalytic inhibitors of Batroxrhagin. However, there are in vitro studies that have described similar metalloprotease inhibitors. The inhibitor batimastat was used as a leading compound for the search and selection of similar candidates. This molecule is widely cited as a metalloprotease inhibitor and as an antimetastatic. In addition to batimastat-like molecules, four other reported metalloprotease inhibitors were included to compose the study's positive control group. Hence, 580 molecules were tested. The three-dimensional structure of B. atrox Batroxrhagin was predicted based on homologous structures using Modeller 9.20. Molecular docking calculation was performed using Autodock 4.2 and molecular surfaces and interactions were analyzed using Biovia/Discovery Studio 2017. Among 576 molecules, 42 similar to batismast resulted in a better energy of interaction than all positive controls, including batimastat itself. The batimastat-like molecules with lowest energy and positive controls were subjected to molecular dynamics for 30 ns in Gromacs 2019.4. This batimastat-like molecule produced better stability among all the Batroxrhagin-ligand complexes analyzed. Overall, the proposed compounds present justifiable evidence for future in vitro tests aiming to inhibit Batroxrhagin. Communicated by Ramaswamy H. Sarma.

Current situation of snakebites envenomation in the Neotropics: Biotechnology, a versatile tool in the production of antivenoms

Snakebite envenomation is a neglected tropical disease that affects millions of people around the world with a great impact on health and the economy. Unfortunately, public health programs do not include this kind of disease as a priority in their social programs. Cases of snakebite envenomations in the Neotropics are inaccurate due to inadequate disease management from medical records to the choice of treatments. Victims of snakebite envenomation are primarily found in impoverished agricultural areas where remote conditions limit the availability of antivenom. Antivenom serum is the only Food and Drug Administration-approved treatment used up to date. However, it has several disadvantages in terms of safety and effectiveness. This review provides a comprehensive insight dealing with the current epidemiological status of snakebites in the Neotropics and technologies employed in antivenom production. Also, modern biotechnological tools such as transcriptomic, proteomic, immunogenic, high-density peptide microarray and epitope mapping are highlighted for producing new-generation antivenom sera. These results allow us to propose strategic solutions in the Public Health Sector for managing this disease. Keywords: antivenom, biotechnology, neglected tropical disease, omics, recombinant antibody.

First Insights into the Venom Composition of Two Ecuadorian Coral Snakes

Micrurus is a medically relevant genus of venomous snakes composed of 85 species. Bites caused by coral snakes are rare, but they are usually associated with very severe and life-threatening clinical manifestations. Ecuador is a highly biodiverse country with a complex natural environment, which is home to approximately 20% of identified Micrurus species. Additionally, it is on the list of Latin American countries with the highest number of snakebites. However, there is no local antivenom available against the Ecuadorian snake venoms, and the biochemistry of these venoms has been poorly explored. Only a limited number of samples collected in the country from the Viperidae family were recently characterised. Therefore, this study addressed the compositional patterns of two coral snake venoms from Ecuador, M. helleri and M. mipartitus, using venomics strategies, integrating sample fractionation, gel electrophoresis, and mass spectrometry. Chromatographic and electrophoretic profiles of these snake venoms revealed interspecific variability, which was ascertained by mass spectrometry. The two venoms followed the recently recognised dichotomic toxin expression trends displayed by Micrurus species: M. helleri venom contains a high proportion (72%) of phospholipase A₂, whereas M. mipartitus venom is dominated by three-finger toxins (63%). A few additional protein families were also detected in these venoms. Overall, these results provide the first comprehensive views on the composition of two Ecuadorian coral snake venoms and expand the knowledge of Micrurus venom phenotypes. These findings open novel perspectives to further research the functional aspects of these biological cocktails of PLA₂s and 3FTxs and stress the need for the preclinical evaluation of the currently used antivenoms for therapeutic purposes in Ecuador.

Antibacterial Properties of Crotoxin from Crotalus durissus terrificus-Insight into the Mechanism of Action

The growing problem of antibiotic resistance among bacteria requires searching for new therapeutic agents with bacteriostatic and/or bactericidal properties. Crotoxin is a β-neurotoxin from the venom of the Crotalus durissus terrificus. It is composed of two subunits: CA (non-active) and CB (with phospholipase A₂ activity). It has already been shown that the isolated CB, but not the CA, subunit of crotoxin exhibits an antibacterial activity towards a variety of Gram-positive and Gram-negative bacterial species. However, no studies on the whole crotoxin complex have been carried out so far. We tested the antibacterial properties of crotoxin, as well as its isolated CB subunit, towards Staphylococcus aureus ATCC 25923, Staphylococcus aureus ATCC 6535, Micrococcus luteus ATCC 10240, Escherichia coli ATCC 25922, Escherichia coli ATCC 8739, and Pseudomonas aeruginosa ATCC 10145. Both toxins exhibited antibacterial properties only against Micrococcus luteus ATCC 10240. Crotoxin showed only bacteriostatic activity with a MIC of 46 µM, while the CB subunit acted as both a bacteriostatic and bactericidal agent with a MIC = MBC = 0.21 μM. The bacteriostatic effect of the toxins was independent of the enzymatic activity of the CB subunit. Bactericidal properties, however, require phospholipase A₂ activity. Both toxins reduced bacteria viability at the MIC by 72% and 85% for crotoxin- and CB-treated bacteria, respectively. The membrane permeability increased approximately three times within the first hour of incubation with toxins; afterwards, either no significant changes or a decrease of membrane permeability, compared to the control cells, were observed. We isolated a single, approximately 30 kDa bacterial wall protein which belongs to the NlpC/P60 family that interacts with crotoxin leading to the inhibition of bacterial growth. Neither crotoxin nor the CB subunit showed any cytotoxic properties to human fibroblasts at the MIC during the three-day incubation.

Comparative Venom Proteomics of Iranian, Macrovipera lebetina cernovi, and Cypriot, Macrovipera lebetina lebetina, Giant Vipers

Envenoming by Macrovipera lebetina subspecies causes severe life-threatening difficulties for people living in North Africa and the Middle East. To better understand the pathophysiology of envenoming and improve patient management, knowledge about the venom components of the subspecies is essential. Here, the venom proteomes of Macrovipera lebetina lebetina from Cyprus and Macrovipera lebetina cernovi from Iran were characterized using RP-HPLC separation of the crude venom proteins, SDS-PAGE of fractionated proteins, and LC-MS/MS of peptides obtained from in-gel tryptic digestion of protein bands. Moreover, we also used high-resolution shot-gun proteomics to gain more reliable identification, where the whole venom proteomes were subjected directly to in-solution digestion before LC-HR-MS/MS. The data revealed that both venoms consisted of at least 18 protein families, of which snake venom Zn2+-dependent metalloprotease (SVMP), serine protease, disintegrin, phospholipase A2, C-type lectin-like, and L-amino acid oxidase, together accounted for more than 80% of the venoms’ protein contents. Although the two viper venoms shared mostly similar protein classes, the relative occurrences of these toxins were different in each snake subspecies. For instance, P-I class of SVMP toxins were found to be more abundant than P-III class in the venoms of M. l. cernovi compared to M. l. lebetina, which gives hints at a more potent myonecrotic effect and minor systemic hemorrhage following envenoming by M. l. cernovi than M. l. lebetina. Moreover, single-shot proteomics also revealed many proteins with low abundance (<1%) within the venoms, such as aminopeptidase, hyaluronidase, glutaminyl-peptide cyclotransferase, cystatin, phospholipase B, and vascular endothelial growth factor. Our study extends the in-depth understanding of the venom complexity of M. lebetina subspecies, particularly regarding toxin families associated with envenoming pathogenesis and those hard-detected protein classes expressed in trace amounts.

Polymerase chain reaction-based snake origin tracing in commercial venom crystals by targeting the mitochondrial D-loop

Snake venom is a valuable raw material for numerous therapeutic formulations because of its life-saving pharmacological potential. However, due to their high price, fake "snake venoms" have captured a significant portion of the global market, and there is currently no reliable reported DNA-based method available for quickly distinguishing between fakes and originals. Therefore, in this study, a set of newly designed snake-specific universal primers targeting mitochondrial D-loop fragments were employed to detect snake origins in commercial venom crystals by only simplex polymerase chain reaction analysis. Under the optimal thermal cycling conditions, only the 145-149 bp snake-specific mitochondrial D-loop fragments from pure and mixed backgrounds were amplified by the newly designed primers. Specificity was achieved by confirming no DNA amplification occurred in the DNA admixture of ten different chordates, and universality by individual DNA amplification of nine different snakes. The primers that efficiently amplified the minimum mitochondrial DNA contained in a total of 10^-2 ng in a 10.0 μl reaction were also successfully able to detect the snake origin in commercial cobra venom crystals. These findings suggest that the newly designed primers can be used to differentiate the original and fake commercial snake venom crystals in order to achieve the highest standards of snake venom-based medications through amplifying the snake-specific mitochondrial D-loop fragments.

Behavioral disturbances induced by cyanobacterial oligopeptides microginin-FR1, anabaenopeptin-A and microcystin-LR are associated with neuromotoric and cytotoxic changes in Brachionus calyciflorus

Aquatic animals are exposed to various cyanobacterial products released concomitantly to the environment by decaying blooms. Although there exist results on the toxicity of cyanobacterial extracts little is known on the influence of pure oligopeptides or their mixtures and elucidated mechanisms of behavioral toxicity in zooplanktonic organisms. Therefore, the aim of the present study was to assess the effects of single and mixed pure cyanobacterial oligopeptides: microginin FR-1 (MG-FR1), anabaenopeptin-A (ANA-A) and microcystin-LR (MC-LR) at various concentrations on the swimming behavior and catecholamine neurotransmitter activity, muscular F-actin structure, DNA nuclear content and cell viability of a model rotifer Brachionus calyciflorus. Swimming behavior was analyzed with the use of video digital analysis. Fluorescent microscopy imaging was used to analyze neuromotoric biomarkers in the whole organisms: neuromediator release (by staining with EC517 probe), muscle F-actin filaments (by staining with blue phalloidin dye). DNA content and cytotoxicity was also determined by Hoechst 34580 and propidium iodide double staining, respectively. The results showed that single oligopeptides inhibited all the tested endpoints. The binary mixtures induced synergistic interaction on swimming speed except for MG-FR1 +MC-LR which was nearly additive. Both binary and ternary mixtures also synergistically degraded F-actin and triggered cytotoxic effects visible in the whole organisms. Antagonistic inhibitory effects of all the binary mixtures were found on catecholamine neurotransmitter activity, however the ternary mixture induced additive toxicity. Antagonistic effects of both binary and ternary mixtures were also noted on nuclear DNA content. The results of the study suggest that both depression of neurotransmission and impairment of muscle F-actin structure in muscles may contribute to mechanisms of Brachionus swimming speed inhibition by the tested single cyanobacterial oligopeptides and their mixtures. The study also showed that natural exposure of rotifers to mixtures of these cyanobacterial metabolites may result in different level of interactive toxicity with antagonistic, additive synergistic effects depending on the variants and concentrations present in the environment.

Bioactive peptides from venoms against glioma progression

Venoms are complex mixtures of different molecules and ions. Among them, bioactive peptides have been found to affect cancer hallmarks, such as cell proliferation, cell invasion, cell migration, and can also modulate the immune response of normal and cancer-bearing organisms. In this article, we review the mechanisms of action on these cancer cell features, focusing on bioactive peptides being developed as potential therapeutics for one of the most aggressive and deadly brain tumors, glioblastoma (GB). Novel therapeutic approaches applying bioactive peptides may contribute to multiple targeting of GB and particularly of GB stem cells. Bioactive peptides selectively target cancer cells without harming normal cells. Various molecular targets related to the effects of bioactive peptides on GB have been proposed, including ion channels, integrins, membrane phospholipids and even immunomodulatory treatment of GB. In addition to therapy, some bioactive peptides, such as disintegrins, can also be used for diagnostics or are used as labels for cytotoxic drugs to specifically target cancer cells. Given the limitations described in the last section, successful application in cancer therapy is rather low, as only 3.4% of such peptides have been included in clinical trials and have passed successfully phases I to III. Combined approaches of added bioactive peptides to standard cancer therapies need to be explored using advanced GB in vitro models such as organoids. On the other hand, new methods are also being developed to improve translation from research to practice and provide new hope for GB patients and their families.

Therapeutic potential of venom peptides: insights in the nanoparticle-mediated venom formulations

Background

Venoms are the secretions produced by animals, generally for the purpose of self-defense or catching a prey. Biochemically venoms are mainly composed of proteins, lipids, carbohydrates, ions, etc., and classified into three major classes, viz. neurotoxic, hemotoxic and cytotoxic based upon their mode of action. Venoms are composed of different specific peptides/toxins which are responsible for their unique biological actions. Though venoms are generally seen as a source of death, scientifically venom is a complex biochemical substance having a specific pharmacologic action which can be used as agents to diagnose and cure a variety of diseases in humans.

Main body

Many of these venoms have been used since centuries, and their specified therapies can also be found in ancient texts such as Charka Samhita. The modern-day example of such venom therapeutic is captopril, an antihypertensive drug developed from venom of Bothrops jararaca. Nanotechnology is a modern-day science of building materials on a nanoscale with advantages like target specificity, increased therapeutic response and diminished side effects. In the present review we have introduced the venom, sources and related constituents in brief, by highlighting the therapeutic potential of venom peptides and focusing more on the nanoformulations-based approaches. This review is an effort to compile all such report to have an idea about the future direction about the nanoplatforms which should be focused to have more clinically relevant formulations for difficult to treat diseases.

Conclusion

Venom peptides which are fatal in nature if used cautiously and effectively can save life. Several research findings suggested that many of the fatal diseases can be effectively treated with venom peptides. Nanotechnology has emerged as novel strategy in diagnosis, treatment and mitigation of diseases in more effective ways. A variety of nanoformulation approaches have been explored to enhance the therapeutic efficacy and reduce the toxicity and targeted delivery of the venom peptide conjugated with it. We concluded that venom peptides along with nanoparticles can evolve as the new era for potential treatments of ongoing and untreatable diseases.

Graphical Abstract

The chemistry of snake venom and its medicinal potential

The fascination and fear of snakes dates back to time immemorial, with the first scientific treatise on snakebite envenoming, the Brooklyn Medical Papyrus, dating from ancient Egypt. Owing to their lethality, snakes have often been associated with images of perfidy, treachery and death. However, snakes did not always have such negative connotations. The curative capacity of venom has been known since antiquity, also making the snake a symbol of pharmacy and medicine. Today, there is renewed interest in pursuing snake-venom-based therapies. This Review focuses on the chemistry of snake venom and the potential for venom to be exploited for medicinal purposes in the development of drugs. The mixture of toxins that constitute snake venom is examined, focusing on the molecular structure, chemical reactivity and target recognition of the most bioactive toxins, from which bioactive drugs might be developed. The design and working mechanisms of snake-venom-derived drugs are illustrated, and the strategies by which toxins are transformed into therapeutics are analysed. Finally, the challenges in realizing the immense curative potential of snake venom are discussed, and chemical strategies by which a plethora of new drugs could be derived from snake venom are proposed.

Purification, Characterization and Evaluation of the Antitumoral Activity of a Phospholipase A2 from the Snake Bothrops moojeni

Nature presents a wide range of biomolecules with pharmacological potential, including venomous animal proteins. Among the protein components from snake venoms, phospholipases (PLA₂) are of great importance for the development of new anticancer compounds. Thus, we aimed to evaluate the PLA₂ anticancer properties from Bothrops moojeni venom. The crude venom was purified through three chromatographic steps, monitored by enzymatic activity and SDS-PAGE (12%). The purified PLA₂ denominated BmPLA2 had its molecular mass and N-terminal sequence identified by mass spectrometry and Edman degradation, respectively. BmPLA2 was assayed against human epithelial colorectal adenocarcinoma cells (Caco-2), human rhabdomyosarcoma cells (RD) and mucoepidermoid carcinoma of the lung (NCI-H292), using human fibroblast cells (MRC-5) and microglia cells (BV-2) as a cytotoxicity control. BmPLA2 presented 13,836 Da and a 24 amino acid-residue homologue with snake PLA₂, which showed a 90% similarity with other Bothrops moojeni PLA₂. BmPLA2 displayed an IC₅₀ of 0.6 µM against Caco-2, and demonstrated a selectivity index of 1.85 (compared to MRC-5) and 6.33 (compared to BV-2), supporting its selectivity for cancer cells. In conclusion, we describe a new acidic phospholipase, which showed antitumor activity and is a potential candidate in the development of new biotechnological tools.

The myth of cobra venom cytotoxin: More than just direct cytolytic actions

Cobra venom cytotoxin (CTX) is a non-enzymatic three-finger toxin that constitutes 40-60% of cobra venom. Thus, it plays an important role in the pathophysiology of cobra envenomation, especially in local dermonecrosis. The three-finger hydrophobic loops of CTX determine the cytotoxicity. Nevertheless, the actual mechanisms of cytotoxicity are not fully elucidated as they involve not only cytolytic actions but also intracellular signalling-mediated cell death pathways. Furthermore, the possible transition cell death pattern remains to be explored. The actual molecular mechanisms require further studies to unveil the relationship between different CTXs from different cobra species and cell types which may result in differential cell death patterns. Here, we discuss the biophysical interaction of CTX with the cell membrane involving four binding modes: electrostatic interaction, hydrophobic partitioning, isotropic phase, and oligomerisation. Oligomerisation of CTX causes pore formation in the membrane lipid bilayer. Additionally, the CTX-induced apoptotic pathway can be executed via death receptor-mediated extrinsic pathways and mitochondrial-mediated intrinsic pathways. We also discuss lysosomal-mediated necrosis and the occurrence of necroptosis following CTX action. Collectively, we provided an insight into concentration-dependent transition of cell death pattern which involves different mechanistic actions. This contributes a new direction for further investigation of cytotoxic pathways activated by the CTXs for future development of biotherapeutics targeting pathological effects caused by CTX.

NT-proBNP as a predictor of death and cardiovascular events in patients with type 2 diabetes

Existing risk prediction scores based on clinical and laboratory variables have been considered inaccurate in patients with Type 2 Diabetes Mellitus (T2DM). Circulating concentrations of natriuretic peptides have been used to aid in the diagnosis and to predict outcomes in heart failure. However, there is a growing body of evidence for the use of natriuretic peptides measurements, mainly N-terminal pro-B-type natriuretic peptide (NT-proBNP), as a tool in risk stratification for individuals with T2DM. Studies have demonstrated the ability of NT-proBNP to improve outcomes prediction when incorporated into multivariate models. More recently, evidence has emerged of the discriminatory power of NT-proBNP, demonstrating, as a single variable, a similar and even superior ability to multivariate risk models for the prediction of death and cardiovascular events in individuals with T2DM. Natriuretic peptides are synthesized and released from the myocardium as a counter-regulatory response to increased cardiac wall stress, sympathetic tone, and vasoconstriction, acting on various systems and affecting different biological processes. In this article, we present a review of the accumulated knowledge about these biomarkers, underscoring the strength of the evidence of their predictive ability for fatal and non-fatal outcomes. It is likely that, by influencing the functioning of many organs, these biomarkers integrate information from different systems. Although not yet recommended by guidelines, measurement of natriuretic peptides, and particularly NT-proBNP, should be strongly considered in the risk stratification of individuals with T2DM.

Harnessing the Natural Toxic Metabolites in COVID-19

SARS-CoV-2 is a novel coronavirus and the cause of the recent pandemic; it is an enveloped β-coronavirus. SARS-CoV-2 appear in the Wuhan City of China for the first time and outspread worldwide quickly. Due to its person-to-person fast transmission, COVID-19 is becoming a global problem. SARS-CoV-2 enter into cells by using ACE2 receptors that are numerous in the lungs and finally can cause acute respiratory distress syndrome (ARDS). Dry cough, sore throat, fever, body pain, headache, GIT discomfort, diarrhoea, and fatigue are some of the COVID-19 symptoms. There is no definite and certain treatment for disease caused by SARS-CoV-2 till now. Some pharmacological effects of toxins, toxoids, and venoms have been proven, and their effects on some diseases have been evaluated. This study aimed to investigate the role of toxins, toxoids, and venom in the pathophysiology of COVID-19 disease.

Snakebites in Pediatric Patients in Kahramanmaraş: Is Pro-brain Natriuretic Peptide a Prognostic Biomarker for Snakebites?

Background: Snake envenomations are a serious cause of mortality and morbidity in the world.

Aims: This study was conducted to investigate snake bites in pediatric patients in Kahramanmaraş and to determine whether pro-brain natriuretic peptide (proBNP) has a prognostic value in these patients.

Methods: Pediatric patients aged <18 years who presented to the pediatric emergency department with snakebites were reviewed retrospectively. The demographical, clinical, laboratory, treatments, and outcomes data were collected from their medical records. Stage 0 and 1 envenomation was considered as a non-serious complication and stage 2 and 3 envenomation was considered as a serious complication.

Results: A total of 32 pediatric patients, six females and 26 males, between 2016 and 2021, were included in the study. The mean age was 12.52±3.28 years. There were seven patients without serious complications and 25 patients with serious complications. The best cutoff point for proBNP to predict serious complications was found to be ≥272.5 ng∙L^-1 (sensitivity, 83.3%; specificity, 100%, p=0.011). We also detected complex regional pain syndrome in one of our patients.

Conclusions: In this study, proBNP was shown to be predictive of a poor outcome of snakebites. Moreover, complex regional pain syndrome, which is rarely reported in the literature, should be kept in mind during the long-term follow-up of snakebites.