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

Exploration of antimicrobial and anticancer activities of L-amino acid oxidase from Egyptian Naja haje venom

Hepatocellular carcinoma and bacterial resistance are major health burdens nowadays. Thus, providing new therapies that overcome that resistance is of great interest, particularly those derived from nature rather than chemotherapeutics to avoid cytotoxicity on normal cells. Venomous animals are among the natural sources that assisted in the discovery of novel therapeutic regimens. L-amino acid oxidase Nh-LAAO (140 kDa), purified from Egyptian Naja haje venom by a successive two-step chromatography protocol, has an optimal pH and temperature of 8 and 37 °C. Under standard assay conditions, Nh-LAAO exhibited the highest specificity toward L-Arg, L-Met and L-Leu, with Km and Vmax values of 3.5 mM and 10.4 μmol/min/ml, respectively. Among the metal ions, Ca+2, Na+, and K+ ions are activators, whereas Fe+2 inhibited LAAO activity. PMSF and EDTA slightly inhibited the Nh-LAAO activity. In addition, Nh-LAAO showed antibacterial and antifungal activities, particularly against Gentamicin-resistant P. aeruginosa and E. coli strains with MIC of 18 ± 2 μg/ml, as well as F. proliferatum and A. parasiticus among the selected human pathogenic strains. Furthermore, Nh-LAAO exhibited anti-proliferative activity against cancer HepG2 and Huh7 cells with IC50 of 79.37 and 60.11 μg/ml, respectively, with no detectable effect on normal WI-38 cells. Consequently, the apoptosis % of the HepG2 and Huh7 cells were 12 ± 1 and 34.5 ± 2.5 %, respectively, upon Nh-LAAO treatment. Further, the Nh-LAAO arrested the HepG2 and Huh7 cell cycles in the G0/G1 phase. Thus, the powerful selective cytotoxicity of L-amino acid oxidase opens up the possibility as a good candidate for clinical cancer therapy.

Snake venom toxins: Potential anticancer therapeutics

Snake venom contains a cocktail of compounds dominated by proteins and peptides, which make up the toxin. The toxin components of snake venom attack several targets in the human body including the neuromuscular system, kidney and blood coagulation system and cause pathologies. As such, the venom toxins can be managed and used for the treatment of these diseases. In this regard, Captopril used in the treatment of cardiovascular diseases was the first animal venom toxin-based drug approved by the US Food and Drug Administration and the European Medicines Agency. Cancers cause morbidity and mortality worldwide. Due to side effects associated with the current cancer treatments including chemotherapy, radiotherapy, immunotherapy, hormonal therapy and surgery, there is a need to improve the efficacy of current treatments and/or develop novel drugs from natural sources including animal toxin-based drugs. There is a long history of earlier and ongoing studies implicating snake venom toxins as potential anticancer therapies. Here, we review the role of crude snake venoms and toxins including phospholipase A2, L-amino acid oxidase, C-type lectin and disintegrin as potential anticancer agents tested in cancer cell lines and animal tumour models in comparison to normal cell lines. Some of the anti-tumour activities of snake venom toxins include induction of cytotoxicity, apoptosis, cell cycle arrest and inhibition of metastasis, angiogenesis and tumour growth. We thus propose the advancement of multidisciplinary approaches to more pre-clinical and clinical studies for enhanced bioavailability and targeted delivery of snake venom toxin-based anticancer drugs.

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.

Three finger toxins of elapids: structure, function, clinical applications and its inhibitors

The WHO lists snakebite as a "neglected tropical disease". In tropical and subtropical areas, envenoming is an important public health issue. This review article describes the structure, function, chemical composition, natural inhibitors, and clinical applications of Elapids' Three Finger Toxins (3FTX) using scientific research data. The primary venomous substance belonging to Elapidae is 3FTX, that targets nAChR. Three parallel β-sheets combine to create 3FTX, which has four or five disulfide bonds. The three primary types of 3FTX are short-chain, long-chain, and nonconventional 3FTX. The functions of 3FTX depend on the specific toxin subtype and the target receptor or ion channel. The well-known effect of 3FTX is probably neurotoxicity because of the severe consequences of muscular paralysis and respiratory failure in snakebite victims. 3FTX have also been studied for their potential clinical applications. α-bungarotoxin has been used as a molecular probe to study the structure and function of nAChRs (Nicotinic Acetylcholine Receptors). Acid-sensing ion channel (ASIC) isoforms 1a and 1b are inhibited by Mambalgins, derived from Black mamba venom, which hinders their function and provide an analgesic effect. α- Cobra toxin is a neurotoxin purified from Chinese cobra (Naja atra) binds to nAChR at the neuronal junction and causes an analgesic effect for moderate to severe pain. Some of the plants and their compounds have been shown to inhibit the activity of 3FTX, and their mechanisms of action are discussed.

Snake venom, a potential treatment for melanoma. A systematic review

Despite advances in treating patients with melanoma, there are still many treatment challenges to overcome. Studies with snake venom-derived proteins/peptides describe their binding potential, and inhibition of some proliferative mechanisms in melanoma. The combined use of these compounds with current therapies could be the strategic gap that will help us discover more effective treatments for melanoma. The present study aimed to carry out a systematic review identifying snake venom proteins and peptides described in the literature with antitumor, antimetastatic, or antiangiogenic effects on melanoma and determine the mechanisms of action that lead to these anti-tumor effects. Snake venoms contain proteins and peptides which are antiaggregant, antimetastatic, and antiangiogenic. The in vivo results are encouraging, considering the reduction of metastases and tumor size after treatment. In addition to these results, it was reported that these venom compounds could act in combination with chemotherapeutics (Acurhagin-C; Macrovipecetin), sensitizing and preparing tumor cells for treatment. There is a consensus that snake venom is a promising strategy for the improvement of antimelanoma therapies, but it has been little explored in the current context, combined with inhibitors, immunotherapy or tumor microenvironment, for example. We suggest Lebein as a candidate for combination therapy with BRAF inhibitors.

Isolation of the Anticoagulant and Procoagulant Fractions of the Venom of Iranian Endemic Echis carinatus

Background

The venom of Echis carinatus contains both procoagulant and anticoagulant components that can either promote or block the blood coagulation cascade, and some of these components affect platelet function in different ways.

Objectives

The present study focuses on setting up a procedure for the purification of crude venom and designing appropriate clotting tests in order to characterize the procoagulant and anticoagulant fractions of E. carinatus venom.

Methods

Chromatographic methods, including gel filtration, ion-exchange chromatography, and reverse-phase high-performance liquid chromatography (HPLC), were applied for purifying these fractions. Coagulant activity testing, prothrombin time (PT), and activated partial thromboplastin time (APTT) were used to determine procoagulant and anticoagulant properties. For measuring molecular weight, 15% SDS-PAGE electrophoresis with a molecular weight standard ranging from 6.5 to 200 kDa was used.

Results

We obtained five fractions named F₁, F₂, F₃, F₄, and F₅. The F₁ and F₂ fractions showed procoagulant activity, and the F₅ fraction had anticoagulant activity. The molecular weight of F_2.4.2 from fraction F₂ and F_5.1 from fraction F₅ were analyzed by SDS-PAGE electrophoresis under the reducing condition. These factors were identified as a single protein band at the end of purification. The molecular weights of these purified fractions were estimated to be 7.5 kDa and 38 kDa for F_5.1(b) and F_2.4.2(b), respectively.

Conclusions

Our findings suggest an efficient and suitable procedure for the identification and purification of the procoagulant and anticoagulant factors of the venom of Iranian E. carinatus using the PT and APTT assays.

Egyptian cobra (Naja haje haje) venom phospholipase A2: a promising antiviral agent with potent virucidal activity against simian rotavirus and bovine coronavirus

Viral infections are linked to a variety of human diseases. Despite the achievements made in drug and vaccine development, several viruses still lack preventive vaccines and efficient antiviral compounds. Thus, developing novel antiviral agents is of great concern, particularly the natural products that are promising candidates for such discoveries. In this study, we have purified an approximately 15 kDa basic phospholipase A2 (PLA2) enzyme from the Egyptian cobra Naja haje haje venom. The purified N. haje PLA2 showed a specific activity of 22 units/mg protein against 6 units/mg protein for the whole crude venom with 3.67-fold purification. The antiviral activity of purified N. haje PLA2 has been investigated in vitro against bovine coronavirus (BCoV) and simian rotavirus (RV SA-11). Our results showed that the CC50 of PLA2 were 33.6 and 29 µg/ml against MDBK and MA104 cell lines, respectively. Antiviral analysis of N. haje PLA2 showed an inhibition of BCoV and RV SA-11 infections with a therapeutic index equal to 33.6 and 16, respectively. Moreover, N. haje PLA2 decreased the BCoV and RV SA-11 titers by 4.25 log10 TCID50 and 2.5 log10 TCID50, respectively. Thus, this research suggests the potential antiviral activity of purified N. haje PLA2 against BCoV and RV SA-11 infections in vitro.

Potential applications of Chinese herbal medicines with hemostatic properties

Various herbal medicines with hemostatic properties have been applied for centuries to accelerate hemostasis and control bleeding. However, the mechanisms of action and active constituents remain unknown. This report provides an overview of current clinical hemostatic agents and their disadvantages, then focuses on the clinical value of Chinese herbal medicines with unique hemostatic features that modern medicines lack. A comprehensive review of hemostatic agents derived from Chinese herbal medicines and their potential medical applications is also presented.

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.

Comparative Snake Venom Analysis for Facilitating Wildlife Forensics: A Pilot Study

Confirm and authentic identification of species is required for the implementation of wildlife laws in cases of illegal trafficking of snake venoms. Illegally trafficked snake venom might be misidentified with other drugs of abuse, and sometimes, the species of venom-yielding snake cannot be verified. Snake venoms from medically important snake species, Naja naja and Daboia russelii, were procured from Irula Snake Catcher's Society, Tamil Nadu, India. Comparative analyses of both venoms were carried out using SDS-PAGE, LC-MS/MS, ICP-MS, and mtDNA analysis. The protein concentration of Naja naja and Daboia russelii venoms was 76.1% and 83.9%, respectively. SDS analysis showed a distinct banding pattern of both venoms. LC-MS/MS results showed proteins and toxins from 12 to 14 protein families in Naja naja and Daboia russelii venoms. Elemental analysis using ICP-MS showed a different profile of some elements in both venoms. mtDNA analysis of venoms using universal primers against Cyt b gene showed homology with sequence of Naja naja and Daboia russelii genes. The study proposed a template of various conventional and advanced molecular and instrumental techniques with their pros and cons. The template can be used by forensic science laboratories for detection, screening, and confirmatory analysis of suspected venoms of snakes. Clubbing of various techniques can be used to confirm the identification of species of snake from which the alleged venom was milked. The results can be helpful in framing charge-sheets against accused of illegal venom trafficking and can also be used to verify the purity and quality of commercially available snake venoms.

Venom of Viperidae: A Perspective of its Antibacterial and Antitumor Potential

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The emergence of multi-drug resistant bacteria and limitations on cancer treatment represent two important challenges in modern medicine. Biological compounds have been explored with a particular focus on venoms. Although they can be lethal or cause considerable damage to humans, venom is also a source rich in components with high therapeutic potential.

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Viperidae family is one of the most emblematic venomous snake families and several studies highlighted the antibacterial and antitumor potential of viper toxins. According to the literature, these activities are mainly associated to five protein families - svLAAO, Disintegrins, PLA2, SVMPs and C-type lectins- that act through different mechanisms leading to the inhibition of the growth of bacteria, as well as, cytotoxic effects and inhibition of metastasis process. In this review, we provide an overview of the venom toxins produced by species belonging to the Viperidae family, exploring their roles during the envenoming and their pharmacological properties, in order to demonstrate its antibacterial and antitumor potential.

Neglected Venomous Animals and Toxins: Underrated Biotechnological Tools in Drug Development

Among the vast repertoire of animal toxins and venoms selected by nature and evolution, mankind opted to devote its scientific attention—during the last century—to a restricted group of animals, leaving a myriad of toxic creatures aside. There are several underlying and justifiable reasons for this, which include dealing with the public health problems caused by envenoming by such animals. However, these studies became saturated and gave rise to a whole group of animals that become neglected regarding their venoms and secretions. This repertoire of unexplored toxins and venoms bears biotechnological potential, including the development of new technologies, therapeutic agents and diagnostic tools and must, therefore, be assessed. In this review, we will approach such topics through an interconnected historical and scientific perspective that will bring up the major discoveries and innovations in toxinology, achieved by researchers from the Butantan Institute and others, and describe some of the major research outcomes from the study of these neglected animals.

Platelets, Constant and Cooperative Companions of Sessile and Disseminating Tumor Cells, Crucially Contribute to the Tumor Microenvironment

Although platelets and the coagulation factors are components of the blood system, they become part of and contribute to the tumor microenvironment (TME) not only within a solid tumor mass, but also within a hematogenous micrometastasis on its way through the blood stream to the metastatic niche. The latter basically consists of blood-borne cancer cells which are in close association with platelets. At the site of the primary tumor, the blood components reach the TME via leaky blood vessels, whose permeability is increased by tumor-secreted growth factors, by incomplete angiogenic sprouts or by vasculogenic mimicry (VM) vessels. As a consequence, platelets reach the primary tumor via several cell adhesion molecules (CAMs). Moreover, clotting factor VII from the blood associates with tissue factor (TF) that is abundantly expressed on cancer cells. This extrinsic tenase complex turns on the coagulation cascade, which encompasses the activation of thrombin and conversion of soluble fibrinogen into insoluble fibrin. The presence of platelets and their release of growth factors, as well as fibrin deposition changes the TME of a solid tumor mass substantially, thereby promoting tumor progression. Disseminating cancer cells that circulate in the blood stream also recruit platelets, primarily by direct cell-cell interactions via different receptor-counterreceptor pairs and indirectly by fibrin, which bridges the two cell types via different integrin receptors. These tumor cell-platelet aggregates are hematogenous micrometastases, in which platelets and fibrin constitute a particular TME in favor of the cancer cells. Even at the distant site of settlement, the accompanying platelets help the tumor cell to attach and to grow into metastases. Understanding the close liaison of cancer cells with platelets and coagulation factors that change the TME during tumor progression and spreading will help to curb different steps of the metastatic cascade and may help to reduce tumor-induced thrombosis.

Techniques, perspectives, and challenges of bioactive peptide generation: A comprehensive systematic review

Due to the digestible refractory and absorbable structures of bioactive peptides (BPs), they could induce notable biological impacts on the living organism. In this regard, the current study was devoted to providing an overview regarding the available methods for BPs generation by the aid of a systematic review conducted on the published articles up to April 2019. In this context, the PubMed and Scopus databases were screened to retrieve the related publications. According to the results, although the characterization of BPs mainly has been performed using enzymatic and microbial in-vitro methods, they cannot be considered as suitable techniques for further stimulation of digestion in the gastrointestinal tract. Therefore, new approaches for both in-vivo and in-silico methods for BPs identification should be developed to overcome the obstacles that belonged to the current methods. The purpose of this review was to compile the recent analytical methods applied for studying various aspects of food-derived biopeptides, and emphasizing generation at in vitro, in vivo, and in silico.

Kinome scale profiling of venom effects on cancer cells reveals potential new venom activities

The search for novel and relevant cancer therapeutics is continuous and ongoing. Cancer adaptations, resulting in therapeutic treatment failures, fuel this continuous necessity for new drugs to novel targets. Recently, researchers have started to investigate the effect of venoms and venom components on different types of cancer, investigating their mechanisms of action. Receptor tyrosine kinases (RTKs) comprise a family of highly conserved and functionally important druggable targets for cancer therapy. This research exploits the novelty of complex venom mixtures to affect phosphorylation of the epidermal growth factor receptor (EGFR) and related RTK family members, dually identifying new activities and unexplored avenues for future cancer and venom research. Six whole venoms from diverse species taxa, were evaluated for their ability to illicit changes in the phosphorylated expression of a panel of 49 commonly expressed RTKs. The triple negative breast cancer cell line MDA-MB-468 was treated with optimised venom doses, pre-determined by SDS PAGE and Western blot analysis. The phosphorylated expression levels of 49 RTKs in response to the venoms were assessed with the use of Human Phospho-RTK Arrays and analysed using ImageLab 5.2.1 analysis software (BioRad). Inhibition of EGFR phosphorylation occurred with treatment of venom from Acanthoscurria geniculata (Theraphosidae), Heterometrus swammerdami (Scorpionidae), Crotalus durissus vegrandis (Crotalidae) and Naja naja (Elapidae). Western green mamba Dendroaspis viridis venom increased EGFR phosphorylation. Eph, HGFR and HER were the most affected receptor families by venoms. Whilst the importance of these changes in terms of effect on MDA-MB-468 cells' long-term viability and functionality are still unclear, the findings present exciting opportunities for further investigation as potential drug targets in cancer and as tools to understand better how these pathways interact.

Botrops derived hemocoagulase formulation a probable agent for diabetic wound healing

Botroclot is a marketed preparation containing hemocoagulase, which is an enzyme having coagulant activity, isolated from the snake Botrops atrox. This formulation is used in dental surgeries and other minor surgical wounds. However, the formulation remains untested in diabetic wounds. Hence, we proposed a study for the topical application of Botroclot in high-fat diet (HFD) + Streptozotocin (STZ) induced diabetic rats. HFD was fed initially to rats which facilitates the development of insulin resistance. Thereafter, an injection of STZ (40 mg/kg, i.p.) was given. This resulted in the development of diabetes with elevated fasting glucose and impaired glucose tolerance. After stabilization of blood glucose values, wounds were created by punch biopsy on the dorsal side of the palm of the rat to mimic the diabetic wounds frequently seen in the case of humans. Later, the application of Botroclot on these wounds was carried out for 15 days. Topical application of hemocoagulase improved the wound closure and there was a gradual decrease in inflammatory markers and a substantial increase in collagen deposition occurred. Histopathological findings indicated the same, with an increase in granulation tissue suggesting that the topical application moderately improves the wound healing in diabetic rats. We conclude that Botroclot can have a mild to moderate effect in improving collagen deposition and thus wound contraction, improving wound closure in diabetic wounds in rats. This study also establishes the basis for exploration of agents from venom-based sources in diabetic wound healing.

Functional Mining of the Crotalus Spp. Venom Protease Repertoire Reveals Potential for Chronic Wound Therapeutics

Chronic wounds are a major health problem that cause millions of dollars in expenses every year. Among all the treatments used, active wound treatments such as enzymatic treatments represent a cheaper and specific option with a fast growth category in the market. In particular, bacterial and plant proteases have been employed due to their homology to human proteases, which drive the normal wound healing process. However, the use of these proteases has demonstrated results with low reproducibility. Therefore, alternative sources of proteases such as snake venom have been proposed. Here, we performed a functional mining of proteases from rattlesnakes (Crotalus ornatus, C. molossus nigrescens, C. scutulatus, and C. atrox) due to their high protease predominance and similarity to native proteases. To characterize Crotalus spp. Proteases, we performed different protease assays to measure and confirm the presence of metalloproteases and serine proteases, such as the universal protease assay and zymography, using several substrates such as gelatin, casein, hemoglobin, L-TAME, fibrinogen, and fibrin. We found that all our venom extracts degraded casein, gelatin, L-TAME, fibrinogen, and fibrin, but not hemoglobin. Crotalus ornatus and C. m. nigrescens extracts were the most proteolytic venoms among the samples. Particularly, C. ornatus predominantly possessed low molecular weight proteases (P-I metalloproteases). Our results demonstrated the presence of metalloproteases capable of degrading gelatin (a collagen derivative) and fibrin clots, whereas serine proteases were capable of degrading fibrinogen-generating fibrin clots, mimicking thrombin activity. Moreover, we demonstrated that Crotalus spp. are a valuable source of proteases that can aid chronic wound-healing treatments.

The relationship between clinics and the venom of the causative Amazon pit viper (Bothrops atrox)

Snake venoms are complex mixtures of proteins with toxic activities, with many distinct isoforms, affecting different physiological targets, comprised in a few protein families. It is currently accepted that this diversity in venom composition is an adaptive advantage for venom efficacy on a wide range of prey. However, on the other side, variability on isoforms expression has implications in the clinics of human victims of snakebites and in the efficacy of antivenoms. B. atrox snakes are responsible for most of the human accidents in Brazilian Amazon and the type and abundance of protein families on their venoms present individual variability. Thus, in this study we attempted to correlate the individual venom proteome of the snake brought to the hospital by the patient seeking for medical assistance with the clinical signs observed in the same patient. Individual variability was confirmed in venoms of the 14 snakes selected for the study. The abundance of each protein family was quite similar among the venom samples, while the isoforms composition was highly variable. Considering the protein families, the SVMP group presented the best correlation with bleeding disorders and edema. Considering individual isoforms, some isoforms of venom metalloproteinase (SVMP), C-type lectin-like toxins (CTL) and snake venom serine proteinases (SVSP) presented expression levels that with statistically significant positive correlation to signs and symptoms presented by the patients as bleeding disorders, edema, ecchymosis and blister formation. However, some unexpected data were also observed as the correlation between a CTL, CRISP or LAAO isoforms with blister formation, still to be confirmed with a larger number of samples. Although this is still a small number of patient samples, we were able to indicate that venom composition modulates clinical manifestations of snakebites, to confirm at the bedside the prominent role of SVMPs and to include new possible toxin candidates for the development of toxin inhibitors or to improve antivenom selectiveness, important actions for the next generation treatments of snakebites.

Bothrops atrox is a snake of major medical importance in the Amazon. Its venom is specialized to kill preys in the nature, especially because of coagulotoxic and proteolytic activities. B. atrox envenomings cause local inflammation and, in a significant proportion, systemic manifestations, namely bleeding disorders. These signs and symptoms are caused by the various toxins present in the venom of this snake, which act in the organism by different mechanisms. It is not known to what extent the composition of the venom that was inoculated by the snake that caused the envenoming can influence the patient’s clinical condition. To study this subject, this work correlated the constituents of the venom with the clinical manifestations of hospitalized patients, taking advantage of the fact that many patients bring the snake responsible for the bite. The abundance of each toxin family was similar among the venom samples, but the variants composition of each toxin was highly variable. Considering the protein families, a group named metalloproteases (SVMP) presented the best correlation with bleeding disorders and edema. Some variants of venom SVMPs, and other toxin families, such as C-type lectin-like toxins (CTL) and snake venom serine proteinases (SVSP) presented correlation to signs and symptoms presented by the patients as bleeding disorders, edema, ecchymosis and blister formation. Our results show that venom composition modulates clinical manifestations of snakebites.

The Procoagulant Snake Venom Serine Protease Potentially Having a Dual, Blood Coagulation Factor V and X-Activating Activity

A procoagulant snake venom serine protease was isolated from the venom of the nose-horned viper (Vipera ammodytes ammodytes). This 34 kDa glycoprotein, termed VaaSP-VX, possesses five kDa N-linked carbohydrates. Amino acid sequencing showed VaaSP-VX to be a chymotrypsin-like serine protease. Structurally, it is highly homologous to VaaSP-6 from the same venom and to nikobin from the venom of Vipera nikolskii, neither of which have known functions. VaaSP-VX does not affect platelets. The specific proteolysis of blood coagulation factors X and V by VaaSP-VX suggests that its blood-coagulation-inducing effect is due to its ability to activate these two blood coagulation factors, which following activation, combine to form the prothrombinase complex. VaaSP-VX may thus represent the first example of a serine protease with such a dual activity, which makes it a highly suitable candidate to replace diluted Russell’s viper venom in lupus anticoagulant testing, thus achieving greater reliability of the analysis. As a blood-coagulation-promoting substance that is resistant to serpin inhibition, VaaSP-VX is also interesting from the therapeutic point of view for treating patients suffering from hemophilia.

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.

From Synthetic Fragments of Endogenous Three-Finger Proteins to Potential Drugs

The proteins of the Ly6 family have a three-finger folding as snake venom α-neurotoxins, targeting nicotinic acetylcholine receptors (nAChRs), and some of them, like mammalian secreted Ly6/uPAR protein (SLURP1) and membrane-attached Ly-6/neurotoxin (Lynx1), also interact with distinct nAChR subtypes. We believed that synthetic fragments of these endogenous proteins might open new ways for drug design because nAChRs are well-known targets for developing analgesics and drugs against neurodegenerative diseases. Since interaction with nAChRs was earlier shown for synthetic fragments of the α-neurotoxin central loop II, we synthesized a 15-membered fragment of human Lynx1, its form with two Cys residues added at the N- and C-termini and forming a disulfide, as well as similar forms of human SLURP1, SLURP2, and of Drosophila sleepless protein (SSS). The IC₅₀ values measured in competition with radioiodinated α-bungarotoxin for binding to the membrane-bound Torpedo californica nAChR were 4.9 and 7.4 µM for Lynx1 and SSS fragments, but over 300 µM for SLURP1 or SLURP2 fragments. The affinity of these compounds for the α7 nAChR in the rat pituitary tumor-derived cell line GH4C1 was different: 13.1 and 147 µM for SSS and Lynx1 fragments, respectively. In competition for the ligand-binding domain of the α9 nAChR subunit, SSS and Lynx1 fragments had IC₅₀ values of about 40 µM, which correlates with the value found for the latter with the rat α9α10 nAChR expressed in the Xenopus oocytes. Thus, the activity of these synthetic peptides against muscle-type and α9α10 nAChRs indicates that they may be useful in design of novel myorelaxants and analgesics.

Structurally Robust and Functionally Highly Versatile-C-Type Lectin (-Related) Proteins in Snake Venoms

Snake venoms contain an astounding variety of different proteins. Among them are numerous C-type lectin family members, which are grouped into classical Ca²⁺- and sugar-binding lectins and the non-sugar-binding snake venom C-type lectin-related proteins (SV-CLRPs), also called snaclecs. Both groups share the robust C-type lectin domain (CTLD) fold but differ in a long loop, which either contributes to a sugar-binding site or is expanded into a loop-swapping heterodimerization domain between two CLRP subunits. Most C-type lectin (-related) proteins assemble in ordered supramolecular complexes with a high versatility of subunit numbers and geometric arrays. Similarly versatile is their ability to inhibit or block their target molecules as well as to agonistically stimulate or antagonistically blunt a cellular reaction triggered by their target receptor. By utilizing distinct interaction sites differentially, SV-CLRPs target a plethora of molecules, such as distinct coagulation factors and receptors of platelets and endothelial cells that are involved in hemostasis, thrombus formation, inflammation and hematogenous metastasis. Because of their robust structure and their high affinity towards their clinically relevant targets, SV-CLRPs are and will potentially be valuable prototypes to develop new diagnostic and therapeutic tools in medicine, provided that the molecular mechanisms underlying their versatility are disclosed.