Triacontyl p-coumarate: an inhibitor of snake venom metalloproteinases

Exploring metalloproteins found in the secretion of venomous species: Biological role and therapeutical applications

Several species during evolution suffered random mutations in response to various environmental factors, which resulted in the formation of venom in phylogenetically distant species. The composition of the venom of most species is poorly known. Snake venom is well characterized while most species have poorly known composition. In contrast, snake venoms are well characterized which proteins and peptides are the main active and most abundant constituents. 42 protein families have been identified, including metalloproteins known as metalloproteinases. These macromolecules are enzymes with zinc in their active site derived from the disintegrin A and metalloproteinase (ADAM) cellular family and are categorized into three classes (PI, PII and PIII) according to their domain organization. The snake venom metalloproteinases (SVMP) are cytotoxic, neurotoxic, myotoxic and/or hematotoxic with a crucial role in the defense and restraint of prey. In this scenario envenoming represents a danger to human health and has been considered a neglected disease worldwide, particularly in tropical and subtropical countries. Nevertheless, recently advances in "omics" technologies have demonstrated interesting biological activities of SVMPs such as antimicrobial, anticancer, against cardiovascular diseases and nervous system disorders. Metalloproteins have the therapeutic potential to be converted into drugs as other components of the venom have undergone this process (e.g., captopril, tirefiban and eptifibatide). So, this chapter is focused on the metalloproteins found in the secretions of venomous species, highlight some aspects such as structure, biological activity, pharmacological therapeutic potential and on.

Musa spp. cultivars as a neutralising source against some toxic activities of Bothrops and Crotalus genus snake venoms

Accidents involving snakes from Bothrops spp. and Crotalus spp. constitute the most important cause of envenomation in Brazil and Argentina. Musa spp. (banana) have been reported to be used in popular medicine against snakebite by the members of the Canudos Settlement, located in Goiás. In this way, the aim of this work was to evaluate the antivenom effect of the Ouro (AA), Prata (AAB), Prata-anã (AAB) and Figo (ABB) cultivars against in vitro (phospholipase, coagulation and proteolytic) and in vivo (lethality and toxicity) activities caused by the venoms and toxicity (Artemia salina nauplii and Danio rerio embryos) of Musa spp. as well as the annotation of chemical compounds possibly related to these activities. From the in vitro antiophidic tests with the sap, we observed 100% inhibition of the phospholipase and coagulant activities with the cultivars Prata-anã and Figo against the venoms of B. alternatus and C. d. collineatus, B. diporus and B. pauloensis, respectively, and neutralisation of the lethality against the B. diporus venom. It was observed that the cultivars of Musa spp. did not show toxicity against Artemia salina nauplii and Danio rerio embryos. The sap analysis via HPLC-MS/MS allowed the annotation of the 13 compounds: abscisic acid, shikimic acid, citric acid, quinic acid, afzelechin, Glp-hexose, glucose, sucrose, isorhamnetin-3-O-galactoside-6-raminoside, kaempferol-3-glucoside-3-raminoside, myricetin-3-O-rutinoside, procyanidin B1 and rutin. Therefore, it can be seen that Musa spp. is a potential therapeutic agent that can act to neutralise the effects caused by snakebites.

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.

The potential of Brazilian native plant species used in the therapy for snakebites: A literature review

Snakebite envenoming is a potentially fatal disease categorized as a neglected public health issue for not receiving the appropriate attention from national and international health authorities. The most affected people by this problem usually live in poor rural communities, where medical resources are often sparse and, in some instances, there is even a scarcity of serum therapy. The administration of the appropriate antivenom is the only specific treatment available, however it has limited efficacy against venom-induced local effects. In this scenario, various plant species are used as local first aid for the treatment of snakebite accidents in Brazil, and some of them can effectively inhibit lethality, neurotoxicity, hemorrhage, and venom enzymes activities. This review compiles a list of plants used in the treatment of snakebites in Brazil, focusing on the native Brazilian species registered in the databases Pubmed, Scielo, Scopus and Google Scholar. All these searches were limited to peer-reviewed journals written in English, with the exception of a few articles written in Portuguese. The most cited native plant species were Casearia sylvestris Sw., Eclipta prostrata (L.) L., Mikania glomerata Spreng., Schizolobium parahyba (Vell.) S.F.Blake and Dipteryx alata Vogel, all used to decrease the severity of toxic signs, inhibit proteolytic and hemorrhagic activities, thus increasing survival time and neutralizing myotoxicity effects. Different active compounds showing important activity against the snake venoms and their toxins include flavonoids, alkaloids and tannins. Although some limitations to the experimental studies with medicinal plants were observed, including lack of comparison with control drugs and unknown active extracts compounds, species with anti-venom characteristics are effective and considered as candidates for the development of adjuvants in the treatment of snake envenomation. Further studies on the chemistry and pharmacology of traditionally used plant species will help to understand the role that snakebite herbal remedies may display in local medical health systems. It might also contribute to the development of alternative or complementary treatments to reduce the number of severe disabilities and deaths.

Protective effects of novel diazepinone derivatives in snake venom induced sterile inflammation in experimental animals

Snake envenomation leads to the formation of damage-associated molecular patterns (DAMPs), which are mediated by endogenous intracellular molecules. These are recognized by pattern-recognition receptors (PRRs) and can induce sterile inflammation.

AIMS

In the present study, we aim at understanding the mechanisms involved in DAMPs induced sterile inflammation to unravel the novel therapeutic strategies for treating snake bites. The potential of benzodiazepinone derivatives to act against snake venom induced inflammation has been explored in the present investigation.

MAIN METHODS

Three compounds VA 17, VA 43 and PA 03 were taken from our library of synthetic compounds. Oxidative stress markers such as lipid peroxidation, superoxide and nitric oxide were measured along with the analysis of DAMPs (IL6, HMGB1, vWF, S100b and HSP70). These compounds have been docked using molecular docking against the snake venom PLA₂ structure (PDB code: 1OXL).

KEY FINDINGS

The compounds have been found to effectively neutralize viper and cobra venoms induced lethal activity both ex vivo and in vivo. The compounds have also neutralized the viper venom induced hemorrhagic, coagulant, anticoagulant reactions as well as inflammation. The fold of protection have always been found to be higher in case of ex vivo than in in vivo. These compounds have neutralized the venom induced DAMPs as exhibited by IL6, HMGB1, vWF, S100b and HSP70. The fold of neutralization is found to be higher in VA 43.

SIGNIFICANCE

The identified compounds could be used as potential candidates for developing treatment of snakebites in areas where antiserums are not yet available.

Plant-Derived Toxin Inhibitors as Potential Candidates to Complement Antivenom Treatment in Snakebite Envenomations

Snakebite envenomations (SBEs) are a neglected medical condition of global importance that mainly affect the tropical and subtropical regions. Clinical manifestations include pain, edema, hemorrhage, tissue necrosis, and neurotoxic signs, and may evolve to functional loss of the affected limb, acute renal and/or respiratory failure, and even death. The standard treatment for snake envenomations is antivenom, which is produced from the hyperimmunization of animals with snake toxins. The inhibition of the effects of SBEs using natural or synthetic compounds has been suggested as a complementary treatment particularly before admission to hospital for antivenom treatment, since these alternative molecules are also able to inhibit toxins. Biodiversity-derived molecules, namely those extracted from medicinal plants, are promising sources of toxin inhibitors that can minimize the deleterious consequences of SBEs. In this review, we systematically synthesize the literature on plant metabolites that can be used as toxin-inhibiting agents, as well as present the potential mechanisms of action of molecules derived from natural sources. These findings aim to further our understanding of the potential of natural products and provide new lead compounds as auxiliary therapies for SBEs.

The potential of phenolic acids in therapy against snakebites: A review

Ophidism is a serious health problem worldwide and is included in the World Health Organization's (WHO's) list of Neglected Tropical Diseases. Although snakebite envenoming requires emergency treatment, currently the only treatment recommended by WHO is serotherapy, which has some disadvantages such as low access to the rural population, low effectiveness in neutralizing local effects, and high cost. In this context, new alternatives for the treatment of snakebites are required. The use of plant-derived compounds to inhibit the effects caused by snake venoms has been the object of a number of studies in recent years. This review aims to provide an up-to-date overview of the use of phenolic acids with therapeutic application against envenomation by snakes of different species. In this sense, structural analysis in silico and biological activities in vivo and in vitro were reported. The acids were subdivided into derivatives of benzoic and cinnamic acids, with derivatives of cinnamic acids being the most studied. Studies have revealed that these compounds are capable of inhibiting local and systemic effects induced by envenomation, and structural analyses indicate that the acids interact with important sites responsible for the action of toxins. Thus, it was reported that phenolic acids showed antiophidic potential, providing insights for future research to develop complementary drugs for the treatment of snakebites.

Isohemigossypolone: Antiophidic properties of a naphthoquinone isolated from Pachira aquatica Aubl

We investigated the antiophidic properties of isohemigossypolone (ISO), a naphthoquinone isolated from the outer bark of the Pachira aquatic Aubl. The inhibition of phospholipase A₂, coagulant, fibrinogenolytic, hemorrhagic and myotoxic activities induced by Bothrops pauloensis venom (Pb) was investigated. For this, we use samples resulting from the incubation of Pb with ISO in different concentrations (1:1, 1:5 and 1:10 w/w), we also evaluated the condition of treatment using ISO after 15 min of venom inoculation. The activities of phospholipase A₂, coagulant, fibrinogenolytic, hemorrhagic and myotoxic induced by the B. pauloensis venom were significantly inhibited when the ISO was pre-incubated with the crude venom. For in vivo neutralization tests, the results were observed even when the ISO was applied after 15 min of inoculation of the venom or metalloprotease (BthMP). Also, to identify the inhibition mechanism, we performed in silico assays, across simulations of molecular coupling and molecular dynamics, it was possible to identify the modes of interaction between ISO and bothropic toxins BmooMPα-I, Jararacussin-I and BNSP-7. The present study shows that naphthoquinone isohemigossypolone isolated from the P. aquatica plant inhibited part of the local and systemic damage caused by venom proteins, demonstrating the pharmacological potential of this compound in neutralizing the harmful effects caused by snakebites.

The synthetic varespladib molecule is a multi-functional inhibitor for PLA2 and PLA2-like ophidic toxins

BACKGROUND

The treatment for snakebites is early administration of antivenom, which can be highly effective in inhibiting the systemic effects of snake venoms, but is less effective in the treatment of extra-circulatory and local effects. To complement standard-of-care treatments such as antibody-based antivenoms, natural and synthetic small molecules have been proposed for the inhibition of key venom components such as phospholipase A₂ (PLA₂) and PLA₂-like toxins. Varespladib (compound LY315920) is a synthetic molecule developed and clinically tested aiming to block inflammatory cascades of several diseases associated with high PLA₂s. Recent studies have demonstrated this molecule is able to potently inhibit snake venom catalytic PLA₂ and PLA₂-like toxins.

METHODS

In vivo and in vitro techniques were used to evaluate the inhibitory effect of varespladib against MjTX-I. X-ray crystallography was used to reveal details of the interaction between these molecules. A new methodology that combines crystallography, mass spectroscopy and phylogenetic data was used to review its primary sequence.

RESULTS

Varespladib was able to inhibit the myotoxic and cytotoxic effects of MjTX-I. Structural analysis revealed a particular inhibitory mechanism of MjTX-I when compared to other PLA₂-like myotoxin, presenting an oligomeric-independent function.

CONCLUSION

Results suggest the effectiveness of varespladib for the inhibition of MjTX-I, in similarity with other PLA₂ and PLA₂-like toxins.

GENERAL SIGNIFICANCE

Varespladib appears to be a promissory molecule in the treatment of local effects led by PLA₂ and PLA₂-like toxins (oligomeric dependent and independent), indicating that this is a multifunctional or broadly specific inhibitor for different toxins within this superfamily.

Natural Inhibitors of Snake Venom Metalloproteinases

Snakebites are a hazard in the tropical world. Although antivenom therapy is effective, it is beset with inherent drawbacks. A better understanding of the major components of snake venoms and their neutralisation will help in improving snakebite treatment. Snake venom metalloproteinases (SVMPs) are responsible for severe haemorrhage, the inhibition of coagulation and platelet aggregation, observed in the victims of snakebite envenoming. Inhibitors from various sources including medicinal plants, animal venoms, and sera are sought to block the pharmacological functions of SVMPs. In this review, we describe the interaction of natural inhibitors with SVMPs. To understand their inhibitory mechanisms, we focussed on the complex structures of these inhibitors and SVMPs. There are three distinct classes of inhibitors; namely, chelators, competitive inhibitors, and non-competitive inhibitors. A small number of inhibitors show their anti-hemorrhagic activity in invivo animal models in treatment mode, but most studies evaluate either invitro neutralisation of enzymatic activity or invivo effects in pre-incubation protocols. We propose the distinct strategies and limitations to design either broad-spectrum or highly selective SVMP inhibitors. The goal of designing broad-spectrum inhibitors against SVMPs capable of effective treatment of snakebites without toxicity has been elusive, probably because of the narrow molecular footprint of inhibitors against a large number of SVMPs with distinct molecular surfaces. Our ability to design highly selective inhibitors is limited by the lack of information of interactions between selective inhibitors and SVMPs. Comparisons of structures of hemorrhagic and non-hemorrhagic SVMPs revealed different distributions of electric charge on the surface of SVMPs, which may be exploited to design specific inhibitors. The specific inhibitors may also be useful to identify target molecules of the SVMPs and help to understand their mechanism of action.

In Silico Molecular Studies of Antiophidic Properties of the Amazonian Tree Cordia nodosa Lam

We carried out surveys on the use of Cordia nodosa Lam. in the jungles of Bobonaza (Ecuador). We documented this knowledge to prevent its loss under the Framework of the Convention on Biological Diversity and the Nagoya Protocol. We conducted bibliographic research and identified quercetrin as a significant bioactive molecule. We studied its in silico biological activity. The selected methodology was virtual docking experiments with the proteins responsible for the venomous action of snakes. The molecular structures of quercetrin and 21 selected toxins underwent corresponding tests with SwissDock and Chimera software. The results point to support its antiophidic use. They show reasonable geometries and a binding free energy of -7 to -10.03 kcal/mol. The most favorable values were obtained for the venom of the Asian snake Naja atra (5Z2G, -10.03 kcal/mol). Good results were also obtained from the venom of the Latin American Bothrops pirajai (3CYL, -9.71 kcal/mol) and that of Ecuadorian Bothrops asper snakes (5TFV, -9.47 kcal/mol) and Bothrops atrox (5TS5, -9.49 kcal/mol). In the 5Z2G and 5TS5 L-amino acid oxidases, quercetrin binds in a pocket adjacent to the FAD cofactor, while in the myotoxic homologues of PLA2, 3CYL and 5TFV, it joins in the hydrophobic channel formed when oligomerizing, in the first one similar to α-tocopherol. This study presents a case demonstration of the potential of bioinformatic tools in the validation process of ethnobotanical phytopharmaceuticals and how in silico methods are becoming increasingly useful for sustainable drug discovery.

Plants and Phytocompounds Active Against Bothrops Venoms

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Snakebite envenomation is an important health problem in tropical countries, with severe human and social consequences. In Latin America, the Bothrops species constitute the main threat to humans, and the envenomation caused by these species quickly develops into severe local tissue damage, including swelling, hemorrhaging, myonecrosis, skin ulceration, and pain. The systemic effects of envenomation are usually neutralized by antivenom serum therapy, despite its intrinsic risks. However, neutralization of local tissue damage remains a challenge. To improve actual therapy, two major alternatives are proposed: the rational design of new specific antibodies for most of the tissue damaging/ poor immunogenic toxins, or the search for new synthetic or natural compounds which are able to inhibit these toxins and complement the serum therapy. Natural compounds isolated from plants, mainly from those used in folk medicine to treat snakebite, are a good choice for finding new lead compounds to improve snakebite treatment and minimize its consequences for the victims. In this article, we reviewed the most promising plants and phytocompounds active against bothropic venoms.

Search for efficient inhibitors of myotoxic activity induced by ophidian phospholipase A2-like proteins using functional, structural and bioinformatics approaches

Ophidian accidents are considered an important neglected tropical disease by the World Health Organization. Particularly in Latin America, Bothrops snakes are responsible for the majority of the snakebite envenomings that are not efficiently treated by conventional serum therapy. Thus, the search for simple and efficient inhibitors to complement this therapy is a promising research area, and a combination of functional and structural assays have been used to test candidate ligands against specific ophidian venom compounds. Herein, we tested a commercial drug (acetylsalicylic acid, ASA) and a plant compound with antiophidian properties (rosmarinic acid, RA) using myographic, crystallographic and bioinformatics experiments with a phospholipase A2-like toxin, MjTX-II. MjTX-II/RA and MjTX-II/ASA crystal structures were solved at high resolution and revealed the presence of ligands bound to different regions of the toxin. However, in vitro myographic assays showed that only RA is able to prevent the myotoxic effects of MjTX-II. In agreement with functional results, molecular dynamics simulations showed that the RA molecule remains tightly bound to the toxin throughout the calculations, whereas ASA molecules tend to dissociate. This approach aids the design of effective inhibitors of PLA2-like toxins and, eventually, may complement serum therapy.

Study on the Anticoagulant or Procoagulant Activities of Type II Phenolic Acid Derivatives

In this study, three type II phenolic acids (caffeic acid, p-hydroxycinnamic acid, and ferulic acid) were used to synthesize a total of 18 phenolic acid derivatives. With molecular docking for molecule design and target protein (factors) screening, in combination with the confirmation of target proteins (factors) by surface plasmon resonance, and the evaluation of haemostatic and anticoagulant activities with five blood assays (plasma recalcification time, prothrombin time, activated partial thromboplastin time, fibrinogen, and thrombin time), the data indicated that caffeic acid derivatives showed certain anticoagulant or procoagulant activities and that two other series contained compounds with the best anticoagulant activities. Using Materials Studio analysis, particular functional groups that affect anticoagulant or procoagulant activities were revealed, and these conclusions can guide the discovery of compounds with better activities.

Structure-Based Discovery of Thiosemicarbazone Metalloproteinase Inhibitors for Hemorrhage Treatment in Snakebites

The venoms of snakes are composed by many toxins, which are responsible for various toxic effects including intense pain, bleeding disorders, and local tissue damage caused by hemorrhage and necrosis. The snake venom metalloproteinases (SVMPs) are proteolytic zinc-dependent enzymes acting in different hemostatic mechanisms. In this work, a structure-based molecular modeling strategy was used for the rational design, by means of a homology 3D model of an SVMP isolated from Bothrops pauloensis venom (BpMP-I), followed by synthesis and in vitro evaluation of new thiosemicarbazones as the first inhibitors of the B. pauloensis SVMP. Besides being effective for the SVMP inhibition, two molecules were shown to be effective also in vivo, inhibiting hemorrhage caused by the B. pauloensis whole venom. Docking studies on metalloproteinases from other snake species suggest that the thiosemicarbazones activity is not confined to BpMP-I, but seems to be a common feature of metzincins.

Medicinal Plants for the Treatment of Local Tissue Damage Induced by Snake Venoms: An Overview from Traditional Use to Pharmacological Evidence

Snakebites are a serious problem in public health due to their high morbimortality. Most of snake venoms produce intense local tissue damage, which could lead to temporary or permanent disability in victims. The available specific treatment is the antivenom serum therapy, whose effectiveness is reduced against these effects. Thus, the search for complementary alternatives for snakebite treatment is relevant. There are several reports of the popular use of medicinal plants against snakebites worldwide. In recent years, many studies have been published giving pharmacological evidence of benefits of several vegetal species against local effects induced by a broad range of snake venoms, including inhibitory potential against hyaluronidase, phospholipase, proteolytic, hemorrhagic, myotoxic, and edematogenic activities. In this context, this review aimed to provide an updated overview of medicinal plants used popularly as antiophidic agents and discuss the main species with pharmacological studies supporting the uses, with emphasis on plants inhibiting local effects of snake envenomation. The present review provides an updated scenario and insights into future research aiming at validation of medicinal plants as antiophidic agents and strengthens the potentiality of ethnopharmacology as a tool for design of potent inhibitors and/or development of herbal medicines against venom toxins, especially local tissue damage.

Inhibitory Effects of Hydroethanolic Leaf Extracts of Kalanchoe brasiliensis and Kalanchoe pinnata (Crassulaceae) against Local Effects Induced by Bothrops jararaca Snake Venom

The species Kalanchoe brasiliensis and Kalanchoe pinnata, both known popularly as "Saião," are used interchangeably in traditional medicine for their antiophidic properties. Studies evaluating the anti-venom activity of these species are scarce. This study aims to characterize the chemical constituents and evaluate the inhibitory effects of hydroethanolic leaf extracts of K. brasiliensis and K. pinnata against local effects induced by Bothrops jararaca snake venom. Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography coupled with Diode Array Detection and Electrospray Mass Spectrometry (HPLC-DAD-MS/MS) were performed for characterization of chemical markers of the extracts from these species. For antiophidic activity evaluation, B. jararaca venom-induced paw edema and skin hemorrhage in mice were evaluated. In both models, hydroethanolic extracts (125-500 mg/kg) were administered intraperitoneally in different protocols. Inhibition of phospholipase enzymatic activity of B. jararaca was evaluated. The HPLC-DAD-MS/MS chromatographic profile of extracts showed some particularities in the chemical profile of the two species. K. brasileinsis exhibited major peaks that have UV spectra similar to flavonoid glycosides derived from patuletin and eupafolin, while K. pinnata showed UV spectra similar to flavonoids glycosides derived from quercetin and kaempferol. Both extracts significantly reduced the hemorrhagic activity of B. jararaca venom in pre-treatment protocol, reaching about 40% of inhibition, while only K. pinnata was active in post-treatment protocol (about 30% of inhibition). In the antiedematogenic activity, only K. pinnata was active, inhibiting about 66% and 30% in pre and post-treatment protocols, respectively. Both extracts inhibited phospholipase activity; however, K. pinnata was more active. In conclusion, the results indicate the potential antiophidic activity of Kalanchoe species against local effects induced by B. jararaca snake venom, suggesting their potential use as a new source of bioactive molecules against bothropic venom.

Protective Effect of the Plant Extracts of Erythroxylum sp. against Toxic Effects Induced by the Venom of Lachesis muta Snake

Snake venoms are composed of a complex mixture of active proteins that induce toxic effects, such as edema, hemorrhage, and death. Lachesis muta has the highest lethality indices in Brazil. In most cases, antivenom fails to neutralize local effects, leading to disabilities in victims. Thus, alternative treatments are under investigation, and plant extracts are promising candidates. The objective of this work was to investigate the ability of crude extracts, fractions, or isolated products of Erythroxylum ovalifolium and Erythroxylum subsessile to neutralize some toxic effects of L. muta venom. All samples were mixed with L. muta venom, then in vivo (hemorrhage and edema) and in vitro (proteolysis, coagulation, and hemolysis) assays were performed. Overall, crude extracts or fractions of Erythroxylum spp. inhibited (20%-100%) toxic effects of the venom, but products achieved an inhibition of 4%-30%. However, when venom was injected into mice before the plant extracts, hemorrhage and edema were not inhibited by the samples. On the other hand, an inhibition of 5%-40% was obtained when extracts or products were given before venom injection. These results indicate that the extracts or products of Erythroxylum spp. could be a promising source of molecules able to treat local toxic effects of envenomation by L. muta venom, aiding in the development of new strategies for antivenom treatment.

An in vitro evaluation of the Native American ethnomedicinal plant Eryngium yuccifolium as a treatment for snakebite envenomation

AIM

At least seven North American tribes specifically mention the use of Eryngium (typically roots) as an anti-snake venom therapy. As snake envenomation is an endemic, life-threatening medical risk, is there a scientific basis for the Native American ethnomedicine? Could this be demonstrated in an assay amenable to mechanistic evaluation and high throughput screening for later isolation and possible evaluation as a source for a lead drug?

MATERIALS AND METHODS

Proteases, mainly metalloproteases, are thought to be the main pathological agents in most American snake venoms. Water extracts of four plant parts of Eryngium yuccifolium were tested for enzyme inhibition in three highly sensitive in vitro protease assays, with multiple venoms.

RESULTS

Interestingly, activity was found in all plant parts, not just the roots, in the general protease assay, also in the most specific assay for collagenases, but less so for elastases where enzymatic activity was low, and against five species of American snake venoms. Inhibition spared the activity of a mammalian elastase, suggesting it has some specificity. In dose response assays, inhibitory activity in extracts of Eryngium was noticeably more effective than randomly chosen plants and comparable to some others.

CONCLUSIONS

All data shown here are consistent with pharmacological inhibition of proteases in at least selected venoms of common venomous snakes by Eryngium extracts. Moreover, as the genus is widely distributed in America, the ethnological practice of using this plant as an anti-snake venom treatment is supportable, may have been common, and suggests further bioactivity and phytochemical studies are warranted.

Zn2+ion of the snake venom metalloproteinase (SVMP) plays a critical role in ligand binding: a molecular dynamics simulation study

Snake venom metalloproteinase (SVMP) is one of the major components of snake venom and it is a root causative agent for edema, local tissue damage, inflammation, blood coagulation and hemorrhage during the snake bite.

PTP1B Inhibitory Effect of Alkyl p-Coumarates from Calystegia soldanella

In this report, the PTP1B inhibitory effect of Calystegia soldanella was investigated. Bioassay-guided fractionation of the crude extracts revealed that the n-hexane fraction had the strongest PTP1B inhibitory effect. Nine known alkyl p-coumarates were isolated from the n-hexane fraction, and each compound was evaluated for its effect on PTP1B. All compounds effectively inhibited PTP1B activity. The IC50 values of the compounds were 3 (10.8 μg/mL) > 2 (15.5 μg/mL) > 7 (26.6 μg/mL) > 1 (37.0 μg/mL) > 8 (41.2 μg/mL) > 9 (43.4 μg/mL) > 5 (44.7 μg/mL) > 4 (>50 μg/mL) > 6 (>50 μg/mL).