Isolation and characterization of an anti-leishmanial disintegrin fromCerastes cerastesvenom

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.

Therapeutic outcome of quercetin nanoparticles on Cerastes cerastes venom-induced hepatorenal toxicity: a preclinical study

Aim: The objective of this study was to investigate the therapeutic potential of quercetin (QT) and QT-loaded poly(lactic-co-glycolic acid) nanoparticles (QT-NPs) on Cerastes cerastes venom-mediated inflammation, redox imbalance, hepatorenal tissue damage and local hemorrhage. Methods: The developed QT-NPs were first submitted to physicochemical characterization and then evaluated in the 'challenge then treat' and 'preincubation' models of envenoming. Results: QT-NPs efficiently alleviated hepatorenal toxicity, inflammation and redox imbalance and significantly attenuated venom-induced local hemorrhage. Interestingly, QT-NPs were significantly more efficient than free QT at 24 h post-envenoming, pointing to the efficacy of this drug-delivery system. Conclusion: These findings highlight the therapeutic potential of QT-NPs on venom-induced toxicity and open up the avenue for their use in the management of snakebite envenoming.

The Potassium Channel Blocker β-Bungarotoxin from the Krait Bungarus multicinctus Venom Manifests Antiprotozoal Activity

Protozoal infections are a world-wide problem. The toxicity and somewhat low effectiveness of the existing drugs require the search for new ways of protozoa suppression. Snake venom contains structurally diverse components manifesting antiprotozoal activity; for example, those in cobra venom are cytotoxins. In this work, we aimed to characterize a novel antiprotozoal component(s) in the Bungarus multicinctus krait venom using the ciliate Tetrahymena pyriformis as a model organism. To determine the toxicity of the substances under study, surviving ciliates were registered automatically by an original BioLaT-3.2 instrument. The krait venom was separated by three-step liquid chromatography and the toxicity of the obtained fractions against T. pyriformis was analyzed. As a result, 21 kDa protein toxic to Tetrahymena was isolated and its amino acid sequence was determined by MALDI TOF MS and high-resolution mass spectrometry. It was found that antiprotozoal activity was manifested by β-bungarotoxin (β-Bgt) differing from the known toxins by two amino acid residues. Inactivation of β-Bgt phospholipolytic activity with p-bromophenacyl bromide did not change its antiprotozoal activity. Thus, this is the first demonstration of the antiprotozoal activity of β-Bgt, which is shown to be independent of its phospholipolytic activity.

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.

Past, Present, and Future of Naturally Occurring Antimicrobials Related to Snake Venoms

This review focuses on proteins and peptides with antimicrobial activity because these biopolymers can be useful in the fight against infectious diseases and to overcome the critical problem of microbial resistance to antibiotics. In fact, snakes show the highest diversification among reptiles, surviving in various environments; their innate immunity is similar to mammals and the response of their plasma to bacteria and fungi has been explored mainly in ecological studies. Snake venoms are a rich source of components that have a variety of biological functions. Among them are proteins like lectins, metalloproteinases, serine proteinases, L-amino acid oxidases, phospholipases type A₂, cysteine-rich secretory proteins, as well as many oligopeptides, such as waprins, cardiotoxins, cathelicidins, and β-defensins. In vitro, these biomolecules were shown to be active against bacteria, fungi, parasites, and viruses that are pathogenic to humans. Not only cathelicidins, but all other proteins and oligopeptides from snake venom have been proteolyzed to provide short antimicrobial peptides, or for use as templates for developing a variety of short unnatural sequences based on their structures. In addition to organizing and discussing an expressive amount of information, this review also describes new β-defensin sequences of Sistrurus miliarius that can lead to novel peptide-based antimicrobial agents, using a multidisciplinary approach that includes sequence phylogeny.

Separation and Analytical Techniques Used in Snake Venomics: A Review Article

The deleterious consequences of snake envenomation are due to the extreme protein complexity of snake venoms. Therefore, the identification of their components is crucial for understanding the clinical manifestations of envenomation pathophysiology and for the development of effective antivenoms. In addition, snake venoms are considered as libraries of bioactive molecules that can be used to develop innovative drugs. Numerous separation and analytical techniques are combined to study snake venom composition including chromatographic techniques such as size exclusion and RP-HPLC and electrophoretic techniques. Herein, we present in detail these existing techniques and their applications in snake venom research. In the first part, we discuss the different possible technical combinations that could be used to isolate and purify SV proteins using what is known as bioassay-guided fractionation. In the second part, we describe four different proteomic strategies that could be applied for venomics studies to evaluate whole venom composition, including the mostly used technique: RP-HPLC. Eventually, we show that to date, there is no standard technique used for the separation of all snake venoms. Thus, different combinations might be developed, taking into consideration the main objective of the study, the available resources, and the properties of the target molecules to be isolated.

Comparative Study of the Effect of Snake Venoms on the Growth of Ciliates Tetrahymena pyriformis: Identification of Venoms with High Antiprotozoal Activity

To search for compounds with antiprotozoal activity, effects of snake venoms on the ciliates Tetrahymena pyriformis was studied. T. pyriformis from subkingdom of Protozoa, including the protozoal pathogens, was used as a model organism to select the venoms that are the most active against parasitic protozoans. Various concentrations of venoms were added to the cells, and the cells that survived after 24 h were counted. Among the six snake species from the Viperidae family, the venom of the viper Vipera berus, which completely killed the cells at 49 μg/mL, was the most active. Among four species from the Elapidae family, the previously studied cobra venoms containing cytotoxins with strong antiprotozoal activity as well as the venom of krait Bungarus multicinctus (10 μg/mL) were the most active. The venoms of the pit vipers and Nikolsky's viper did not show any activity at 12.5 mg/mL. Thus, the venoms of V. berus and B. multicinctus are promising for the isolation of new antiprotozoal compounds.

Antiprotozoal Effect of Snake Venoms and Their Fractions: A Systematic Review

Background: Protozoal infection is a lingering public health issue of great concern, despite efforts to produce drugs and vaccines against it. Recent breakthrough research has discovered alternative antiprotozoal agents encompassing the use of snake venoms and their components to cure these infections. This study collated the existing literature to examine the antiprotozoal effect of snake venoms and their fractions. Methods: We conducted a systematic review following the PRISMA guidelines. The PubMed and Embase databases were searched from their inception until 13 October 2021. Articles were screened at the title, abstract and full-text phases. Some additional studies were obtained through the manual search process. Results: We identified 331 studies via the electronic database and manual searches, of which 55 reporting the antiprotozoal effect of snake venoms and their components were included in the review. Around 38% of studies examined the effect of whole crude venoms, and a similar percentage evaluated the effect of a proportion of enzymatic phospholipase A2 (PLA2). In particular, this review reports around 36 PLA2 activities and 29 snake crude venom activities. We also report the notable phenomenon of synergism with PLA2 isoforms of Bothrops asper. Importantly, limited attention has been given so far to the antiprotozoal efficacies of metalloproteinase, serine protease and three-finger toxins, although these venom components have been identified as significant components of the dominant venom families. Conclusion: This study highlights the impact of snake venoms and their fractions on controlling protozoal infections and suggests the need to examine further the effectiveness of other venom components, such as metalloproteinase, serine protease and three-finger toxins. Future research questions in this field must be redirected toward synergism in snake venom components, based on pharmacological usage and in the context of toxicology. Ascertaining the effects of snake venoms and their components on other protozoal species that have not yet been studied is imperative.

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.

Isolation and Characterization of CD39-like Phosphodiesterase (Cc-PDE) from Cerastes cerastes Venom: Molecular Inhibitory Mechanism of Antiaggregation and Anticoagulation

BACKGROUND

Cerastes cerastes venom contains several bioactive proteins with inhibitory potential of platelet aggregation and blood coagulation.

OBJECTIVE

The current study deals with purification, characterization and determination of structural properties of Cc-PDE, the first phosphodiesterase from Cerastes cerastes venom.

MATERIAL AND METHODS

The purification process consists of three successive chromatographies including G75-Sephadex size exclusion, DEAE exchange chromatography and affinity using Sildenafil as a main PDEs' specific inhibitor. The amino acid sequence of purified Cc-PDE was determined by liquid chromatography coupled off line to MALDI-TOF/TOF. Modeling and structural features were obtained using several bioinformatics tools. In vivo and in vitro antiplatelet aggregation and anticoagulant assays were performed.

RESULTS

Cc-PDE (73 506.42 Da) is a 654-residue single polypeptide with 1-22 signal peptide and it is characterized by the presence of predominant basic amino acids suitable to alkaline pI (8.17). Cc-PDE structure is composed of β-strands (17%) and α-helices (24%) and it shares a high identity with homologous snake venom PDEs. Cc-PDE hydrolyzes both Bis-p-nitrophenyl phosphate (Km = 2.60 ± 0.95 mM, Vmax = 0.017 ± 0.002569 μmol.min-1) and p-nitrophenyl phosphate (Km = 7.13 mM ± 0.04490 mM, Vmax = 0.053 ±0.012 μmol.min-1). Cc-PDE prevents ADP- and ATP-induced platelet aggregation by hydrolyzing ADP and ATP, reducing surface P-selectin expression and attenuating platelet function. In addition, Cc-PDE inhibits coagulation factors involved in the intrinsic pathway demonstrated by a significant prolongation of activated partial thromboplastin time and in vivo long-lasting anticoagulation.

CONCLUSION

The obtained results revealed that Cc-PDE may have a therapeutic potential and could be a remedy for thromboembolic diseases as an alternative of anticoagulant and antiplatelet aggregation chemical origins.

"Computational and Functional Characterization of a Hemorrhagic Metalloproteinase Purified from Cerastes cerastes Venom"

Structural and functional aspects of snake venoms metalloproteinases (SVMPs) have been extensively studied due to their role in envenomation. However, in the detection of certain coagulation disorders these biomolecules have been used and applied for the production of new thrombolytic drugs. CcMP-II, a SVMP-II metalloproteinase with a hemorrhagic activity, isolated from the venom of Cerastes cerastes, its sequence of 472 amino acids was identified. Predicted 3D structure showed an arrangement of CcMP-II into two distinct domains: i) a metalloproteinase domain where the zinc-binding motif is found (HXXGHNLGIDH) in addition to the sequence Cys-Ile-Met (CIM) at the Met-turn and ii) disintegrin-like domain containing RGD motif. CcMP-II inhibits platelet aggregation induced by collagen in a dose-dependent manner with an IC₅₀ value estimated of 0.11 nM. This proteinase inhibits also aggregation of platelet stimulated by collagen even if the metal chelating agents (EDTA and 1, 10-phenontroline) are present suggesting that anti-aggregating effect is not due to its metalloproteinase domain, but to its disintegrin-like domain. Capillary pathological modifications caused by CcMP-II following intramuscular injection have as well been examined in mice. The key morphological alterations of the capillary vessels were clearly apparent from the ultrastructural study. The CcMP-II can play a key function in the pathogenesis of disorders that occurs following envenomation of Cerastes cerastes. The three-dimensional model of CcMP-II was built to explain structure-function relationships in ADAM/ADAMTs, a family of proteins having significant therapeutic potential. In order to explain structure-function relationships in ADAM / ADAMT, a family of proteins with considerable therapeutic potential, the three-dimensional model of CcMP-II was constructed.

Isolation and Functional Identification of an Antiplatelet RGD-Containing Disintegrin from Cerastes cerastes Venom

The current report focuses on purification, structural and functional characterization of Cerastategrin from Cerastes cerastes venom, a novel basic disintegrin (pI 8.36) with 128 amino acid residues and a molecular weight of 13 835.25 Da measured by MALDI-MSMS. The 3D structure of Cerastategrin is organized as α-helix (13%), β-strand (15%) and disordered structure (30%) and presents homologies with several snake venom disintegrins. Structural modeling shows that Cerastategrin presents an RGD motif that connects specifically to integrin receptors. Cerastategrin exhibits the inhibition of ADP induced platelets with an IC₅₀ of 0.88 µg/mL and shows in vivo long stable anticoagulation effect 24 h post-injection of increasing doses ranging from 0.2 to 1 mg/kg, therefore, Cerastategrin maintained irreversibly the blood incoagulable. Moreover, Cerastategrin decreases the amount of bounded αIIbβ3 and reduced significantly the quantity of externalized P-Selectin. Cerastategrin acts as a molecule targeting specifically the receptor α_IIbβ₃; therefore, it behaves as a potent platelet activation inhibitor. As a new peptide with promising pharmacological properties, Cerastategrin could have a potential therapeutical effect in the vascular pathologies and may be a new effective treatment approach.

Screening Snake Venoms for Toxicity to Tetrahymena Pyriformis Revealed Anti-Protozoan Activity of Cobra Cytotoxins

Snake venoms possess lethal activities against different organisms, ranging from bacteria to higher vertebrates. Several venoms were shown to be active against protozoa, however, data about the anti-protozoan activity of cobra and viper venoms are very scarce. We tested the effects of venoms from several snake species on the ciliate Tetrahymena pyriformis. The venoms tested induced T. pyriformis immobilization, followed by death, the most pronounced effect being observed for cobra Naja sumatrana venom. The active polypeptides were isolated from this venom by a combination of gel-filtration, ion exchange and reversed-phase HPLC and analyzed by mass spectrometry. It was found that these were cytotoxins of the three-finger toxin family. The cytotoxins from several cobra species were tested and manifested toxicity for infusorians. Light microscopy revealed that, because of the cytotoxin action, the infusorians’ morphology was changed greatly, from teardrop-like to an almost spherical shape, this alteration being accompanied by a leakage of cell contents. Fluorescence microscopy showed that the fluorescently labelled cytotoxin 2 from cobra N. oxiana was localized mainly at the membrane of killed infusorians, indicating that cytotoxins may kill T. pyriformis by causing membrane rupture. This work is the first evidence of the antiprotozoal activity of cobra venom cytotoxins, as demonstrated by the example of the ciliate T. pyriformis.

Hitchhiking with Nature: Snake Venom Peptides to Fight Cancer and Superbugs

Abstract

For decades, natural products in general and snake venoms (SV) in particular have been a rich source of bioactive compounds for drug discovery, and they remain a promising substrate for therapeutic development. Currently, a handful of SV-based drugs for diagnosis and treatment of various cardiovascular disorders and blood abnormalities are on the market. Likewise, far more SV compounds and their mimetics are under investigation today for diverse therapeutic applications, including antibiotic-resistant bacteria and cancer. In this review, we analyze the state of the art regarding SV-derived compounds with therapeutic potential, focusing on the development of antimicrobial and anticancer drugs. Specifically, information about SV peptides experimentally validated or predicted to act as antimicrobial and anticancer peptides (AMPs and ACPs, respectively) has been collected and analyzed. Their principal activities both in vitro and in vivo, structures, mechanisms of action, and attempts at sequence optimization are discussed in order to highlight their potential as drug leads.

Key Contribution

This review describes the state of the art in snake venom-derived peptides and their therapeutic applications. This work reinforces the potential of snake venom components as therapeutic agents, particularly in the quest for new antimicrobial and anticancer drugs.

Isolation and characterization of cytotoxic and insulin-releasing components from the venom of the black-necked spitting cobra Naja nigricollis (Elapidae)

Four peptides with cytotoxic activity against BRIN-BD11 rat clonal β-cells were purified from the venom of the black-necked spitting cobra Naja nigricollis using reversed-phase HPLC. The peptides were identified as members of the three-finger superfamily of snake toxins by ESI-MS/MS sequencing of tryptic peptides. The most potent peptide (cytotoxin-1N) showed strong cytotoxic activity against three human tumor-derived cell lines (LC₅₀ = 0.8 ± 0.2 μM for A549 non-small cell lung adenocarcinoma cells; LC₅₀ = 7 ± 1 μM for MDA-MB-231 breast adenocarcinoma cells; and LC₅₀ = 9 ± 1 μM for HT-29 colorectal adenocarcinoma cells). However, all the peptides were to varying degrees cytotoxic against HUVEC human umbilical vein endothelial cells (LC₅₀ in the range 2–22 μM) and cytotoxin-2N was moderately hemolytic (LC₅₀ = 45 ± 3 μM against mouse erythrocytes). The lack of differential activity against cells derived from non-neoplastic tissue limits their potential for development into anti-cancer agents. In addition, two proteins in the venom, identified as isoforms of phospholipase A₂, effectively stimulated insulin release from BRIN-BD11 cells (an approximately 6-fold increase in rate compared with 5.6 mM glucose alone) at a concentration (1 μM) that was not cytotoxic to the cells suggesting possible application in therapy for Type 2 diabetes.

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Four members of the three-finger superfamily of toxins were isolated from N. nigricollis venom.

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All peptides were cytotoxic to human tumor-derived cells.

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The peptides were also cytotoxic to non-neoplastic HUVEC cells.

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Two isoforms of phospholipase A₂ effectively stimulated insulin release from rat clonal β-cells.