Diosmin: A Daboia russelii venom PLA2s inhibitor- purified, and characterized from Oxalis corniculata L medicinal plant

ETHNOPHARMACOLOGICAL RELEVANCE

Oxalis corniculata L is a medicinal plant that belongs to the Oxalidaceae family. It is a little, slow-growing plant with a frail appearance typically found in mild temperate and tropical areas like Pakistan and India. This plant also includes many other bioactive substances, including alkaloids, flavonoids, terpenoids, cardiac glycosides, saponins, phlobatannins, and steroids.

AIM OF THE STUDY

To investigate the anti-inflammatory effects of Compound diosmin, which is derived from Oxalis corniculata L, on VRV-PL-5 and VRV-PL-8a isolated from Vipera russelli.

MATERIALS AND METHODS

Extraction, purification, and characterization of bioactive by TLC, HPTLC, FT-IR analysis, UV-Vis spectrophotometer, LC-MS/MS Analysis, NMR, XRD Analysis, In vitro evaluation, Circular dichroism spectroscopy, in vivo, and in silico studies.

RESULTS

In this study, the extract of Oxalis corniculata was evaluated for its in vitro and in vivo anti-inflammatory effect against PLA2. The methanolic extract decreased hemolytic activity by about 60% at 1:75 w/w and neutralized the hemolytic activity completely at 1:100 w/w concentration. Diosmin inhibited VRV-PL-5 and VRV-PL-8a in a dose-dependent manner, with the extent of inhibition being about 56% for VRV-PL-5120 μM and VRV-PL-8a by 62% at the same concentration with IC50 concentrations of 87.08 μM for VRV-PL-5 and 82.08 μM for VRV-PL-8a, while at 75 μM. Diosmin inhibited the hemolytic activity of VRV-PL-5 by about 85%, and at the same concentration, VRV-PL-8a inhibited by about 75%. UV-CD spectra at the IC50 concentration of diosmin disrupted the secondary structure of VRV-PL-5 &VRV-PL-8a. In vivo, studies showed decreased myotoxicity and cardiotoxicity of the VRV-PL-5 &VRV-PL-8a, which was seen in the decrease in cytoplasmic markers LDH and CPK levels in the serum when incubated with diosmin. Furthermore, Histopathological studies of Muscles and lungs revealed that diosmin considerably protects against cellular abnormality caused by VRV-PL-5 & VRV-PL-8a. Molecular docking, MM/GBSA, and molecular dynamics simulation studies show that the diosmin is a potent inhibitor for VRV-PL-5 and VRV-PL-8a.

CONCLUSION

This study shows that diosmin is a potentially effective VRV-PL-5 and VRV-PL-8a.

Proteome analysis of Daboia russelii venom, a medically important snake from the Indian sub-continent

Daboia russelii is a category-I medically important snake throughout the Indian sub-continent contributing to majority of snakebite incidences in this part of the world. As such, extensive studies on its venom composition and search of efficient and appropriate interventions for its treatment become crucial. In this study, the proteome of Daboia russelii venom from Tanore, Rajshahi, Bangladesh was profiled using a combination of chromatographic and mass spectrometric techniques. A total of 37 different proteins belonging to 11 different snake venom protein families were detected. Proteomics analysis revealed the presence of major phospholipase A2 toxins. Daboiatoxin (both A and B subunits), the main lethal PLA2 toxin in the venom of Daboia siamensis (Myanmar viper) which is neurotoxic, myotoxic and cytotoxic was detected. Presence of Daboxin P, which is a major protein in the venom of Indian Daboia russelii with strong anticoagulant activity, was also observed. Inconsistent distribution of such lethal toxins in the venom of same species calls for more investigations of snake venoms from lesser explored regions and formulation of better alternatives to the current antivenom therapy for efficient treatment.

Evaluation of Neutralization Potential of Naja naja and Daboiarusselii Snake Venom by Root Extract of Cyanthillium cinereum

Aim

One of the main reasons for the death due to snake bites is the non-availability of antivenoms in the regions where they are needed. The use of medicinal plants and plant-based natural products as an alternative to antivenom will become a milestone in snake bite envenomation. The present study investigates the in vitro antivenom properties of Cyanthillium cinereum root extracts.

Materials and methods

The C. cinereum root's aqueous extract was prepared by the Soxhlet extraction method, and phytochemical screening was performed to detect the presence of various bioactive compounds. Thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) analysis were performed for the detection and identification of phytochemical constituents. In this study, an in vitro model is used to assess the antivenom capability of aqueous extract. Venom toxicity and neutralization assays were as follows: An in vitro pharmacological evaluation was performed by direct hemolysis assay, indirect hemolytic assay, proteolytic activity, neutralization of procoagulant activity, and gelatin liquefaction method.

Results

Qualitative analysis of phytochemicals by the standard method showed the presence of various phytochemical constituents. Also, GC-MS analysis showed the presence of three major compounds that possess antivenom activity from the obtained 60 bioactive compounds, and their chemical structures were also determined. Venom protein profiling was performed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The plant extract was able to neutralize the Naja naja (N. naja) and Daboia russelii (D. russelii) venom induced hemolysis and it was reduced below 50 and 40%, respectively and the extract was also able to reduce the hemolytic halo produced by venoms. Procoagulant activity and gelatin liquefaction assay showed that venom-induced clotting was neutralized by increasing the root extract concentration sufficiently.

Conclusion

The aqueous extract of the root of C. cinereum showed potent in vitro venom-neutralizing activity, and it can be used as a formidable therapeutic agent against N. naja and D. russelii envenomation.

How to cite this article

Suji S, Dinesh MD, Keerthi KU, Anagha KP, Arya J, Anju KV. Evaluation of Neutralization Potential of Naja naja and Daboia russelii Snake Venom by Root Extract of Cyanthillium cinereum. Indian J Crit Care Med 2023;27(11):821-829.

Analytical Size Exclusion Chromatography Coupled with Mass Spectrometry in Parallel with High-Throughput Venomics and Bioassaying for Venom Profiling

Modern analytical size exclusion chromatography (SEC) is a suitable technique to separate venom toxin families according to their size characteristics. In this study, a method was developed to separate intact venom toxins from Bungarus multicinctus and Daboia russelii venoms via analytical SEC using volatile, non-salt-containing eluents for post-column mass spectrometry, coagulation bioassaying and high-throughput venomics. Two venoms were used to demonstrate the method developed. While the venom of Bungaurs multicinctus is known to exert anticoagulant effects on plasma, in this study, we showed the existence of both procoagulant toxins and anticoagulant toxins. For Daboia russelii venom, the method revealed characteristic procoagulant effects, with a 90 kDa mass toxin detected and matched with the Factor X-activating procoagulant heterotrimeric glycoprotein named RVV-X. The strong procoagulant effects for this toxin show that it was most likely eluted from size exclusion chromatography non-denatured. In conclusion, the separation of snake venom by size gave the opportunity to separate some specific toxin families from each other non-denatured, test these for functional bioactivities, detect the eluting mass on-line via mass spectrometry and identify the eluted toxins using high-throughput venomics.

Neutrophil-mediated erythrophagocytosis following Russell's viper (Daboia russelii) bite

Snakebite envenomation is regarded as a high-priority neglected tropical disease by the World Health Organisation, as it results in significant loss of lives and permanent disabilities. Russell's viper is one of the snakes that causes morbidities, mortalities and disabilities in India. The clinical presentation of Russell's viper envenomation is characterised by local envenoming effects, tissue damage, venom-induced coagulopathy, neurotoxicity, and kidney injury. However, venom composition and its mechanisms of toxicity are highly variable even within snakes of the same species including Russell's viper. This variation in venom composition results in a broad range of clinical complications. Here we present a previously undocumented case of neutrophil-mediated erythrophagocytosis in a healthy 28-year-old female following Russell's viper bite. Systemic envenomation effects and bleeding abnormalities in this patient were corrected by the administration of polyvalent antivenom. Two days later, the patient developed progressive swelling and ecchymosis in the bitten limb. Observed abnormal limits within blood testing were followed up by a peripheral blood smear where it was found that 30% of neutrophils had phagocytosed erythrocytes as they were found within the cytoplasm. The patient underwent a fasciotomy for compartmental syndrome and received packed red cells and a course of corticosteroids. Following this treatment, the patient made a full recovery. This case report outlines a previously undocumented pathological event induced by Russell's viper envenomation, guiding diagnosis and treatment. Clinicians' knowledge of the mechanisms of toxicity of Russell's viper envenomation and its clinical manifestations are essential for improving the treatment of snakebites to achieve positive outcomes.

The Effectiveness of Antibiotics in Managing Bacterial Infections on Bite Sites following Snakebite Envenomation

Snakebite envenomation (SBE) is a life-threatening medical emergency with a high mortality rate. Common secondary complications following SBE, such as wound infections, are significant due to their impact on worsening local tissue damage and causing systemic infection. Antivenoms are not effective to treat wound infections following SBE. Moreover, in several rural clinical settings, broad-spectrum antibiotics are often used without clear guidelines or based on limited laboratory data, resulting in undesirable side effects and exacerbated treatment costs. Therefore, robust antibiotic strategies should be developed to tackle this critical issue. Currently, there is limited information available on the bacterial profiles of SBE-induced infections and antibiotic susceptibility. Hence, it is essential to improve the knowledge of bacterial profiles and their antibiotic sensitivity in SBE victims to develop better treatment strategies. This study aimed to address this issue by examining the bacterial profiles of SBE victims with a specific focus on Russell's viper envenomation. The most frequently found bacteria in the bites of SBE victims were Staphylococcus aureus, Klebsiella sp., Escherichia coli, and Pseudomonas aeruginosa. Linezolid, clindamycin, colistin, meropenem, and amikacin were some of the most effective antibiotics for commonly grown bacteria in SBE victims. Similarly, ciprofloxacin, ampicillin, amoxiclave, cefixime, and tetracyclin were the least effective antibiotics for common bacteria found in the wound swabs of SBE victims. These data provide robust guidance for infection management following SBE and offer useful insights to aid in designing effective treatment protocols for SBE with serious wound infections in rural areas where laboratory facilities may not be readily available.

Russell's viper envenomation induces rectus sheath haematoma

Snakebite envenomation causes systemic and local manifestations, which result from the individual or synergistic actions of multiple venom components. The pathological hallmarks of medically important venomous snakes such as the Indian Russell's viper (Daboia russelii) are well known. Envenomation by Russell's viper is typically characterised by coagulopathies, muscular damage, nephrotoxicity, and neurotoxicity. However, recent reports have revealed several unusual complications that provide a better understanding of Russell's viper envenomation effects. To further strengthen this, here, we report a case of Russell's viper bite that induced acute abdominal pain, which was intensified on day two and conservatively treated under medical supervision. Both Fothergill and Carnett signs were positive for this patient. An ultrasound imaging revealed a dissimilar dense mass, and the abdominal computed tomography scan confirmed rectus sheath haematoma. The clinical management involved the administration of polyvalent antivenom, packed red blood cells, fresh frozen plasma, and platelets. The patient recovered gradually and was discharged from the hospital eight days after the bite. Overall, this case presentation shares an uncommon experience and adds new insights into the complex series of rare pathological events associated with Russell's viper bites in India. The scientific documentation of relatively infrequent entities based on an ongoing living assessment of medical experiences, for example, this rectus sheath haematoma, constitutes valuable guidance for an adequate diagnosis and timely treatment. Essential awareness among clinicians and further research on understanding the molecular relationship between Russell's viper venom and rectus sheath haematoma will improve patient outcomes and understanding of this condition, respectively.

The Middle Eastern Cousin: Comparative Venomics of Daboia palaestinae and Daboia russelii

Among the medically most important snakes in the world, the species belonging to the genus Daboia have been attributed to the highest number of human envenomings, deaths and disabilities. Given their significant clinical relevance, the venoms of Russell's vipers (D. russelii and D. siamensis) have been the primary focus of research. In contrast, the composition, activity, ecology and evolution of venom of its congener, the Palestine viper (D. palaestinae), have remained largely understudied. Therefore, to unravel the factors responsible for the enhanced medical relevance of D. russelii in comparison to D. palaestinae, we comparatively evaluated their venom proteomes, biochemical activities, and mortality and morbidity inflicting potentials. Furthermore, the synthesis and regulation of venom in snakes have also remained underinvestigated, and the relative contribution of each venom gland remains unclear. We address this knowledge gap by sequencing the tissue transcriptomes of both venom glands of D. palaestinae, and comparatively evaluating their contribution to the secreted venom concoction. Our findings highlight the disparity in the venom composition, function and toxicities of the two Daboia species. We also show that toxin production is not partitioned between the two venom glands of D. palaestinae.

A Contemporary Exploration of Traditional Indian Snake Envenomation Therapies

Snakebite being a quick progressing serious situation needs immediate and aggressive therapy. Snake venom antiserum is the only approved and effective treatment available, but for selected snake species only. The requirement of trained staff for administration and serum reactions make the therapy complicated. In tropical countries where snakebite incidence is high and healthcare facilities are limited, mortality and morbidities associated with snake envenomation are proportionately high. Traditional compilations of medical practitioners’ personal journals have wealth of plant-based snake venom antidotes. Relatively, very few plants or their extractives have been scientifically investigated for neutralization of snake venom or its components. None of these investigations presents enough evidence to initiate clinical testing of the agents. This review focuses on curating Indian traditional snake envenomation therapies, identifying plants involved and finding relevant evidence across modern literature to neutralize snake venom components. Traditional formulations, their method of preparation and dosing have been discussed along with the investigational approach in modern research and their possible outcomes. A safe and easily administrable small molecule of plant origin that would protect or limit the spread of venom and provide valuable time for the victim to reach the healthcare centre would be a great lifesaver.

In Vitro Neutralization of the Myotoxicity of Australian Mulga Snake (Pseudechis australis) and Sri Lankan Russell's Viper (Daboia russelii) Venoms by Australian and Indian Polyvalent Antivenoms

We studied the neutralisation of Sri Lankan Russell's viper (Daboia russelii) and Australian mulga snake (Pseudechis australis) venom-induced myotoxicity by Indian (Vins and Bharat) and Australian (Seqirus) polyvalent antivenoms, using the in vitro chick biventer skeletal muscle preparation. Prior addition of Bharat or Vins antivenoms abolished D. russelii venom (30 µg/mL)-mediated inhibition of direct twitches, while Australian polyvalent antivenom was not protective. Bharat antivenom prevented, while Vins and Australian polyvalent antivenoms partially prevented, the inhibition of responses to exogenous KCl. Myotoxicity of Mulga venom (10 µg/mL) was fully neutralised by the prior addition of Australian polyvalent antivenom, partially neutralised by Vins antivenom but not by Bharat antivenom. Although the myotoxicity of both venoms was partially prevented by homologous antivenoms when added 5 min after the venom, with an increasing time delay between venom and antivenom, the reversal of myotoxicity gradually decreased. However, antivenoms partially prevented myotoxicity even 60 min after venom. The effect of antivenoms on already initiated myotoxicity was comparable to physical removal of the toxins by washing the bath at similar time points, indicating that the action of the antivenoms on myotoxicity is likely to be due to trapping the toxins or steric hindrance within the circulation, not allowing the toxins to reach target sites in muscles.

Taxon-selective venom variation in adult and neonate Daboia russelii (Russell's Viper), and antivenom efficacy

Major variations in venom composition can occur between juvenile and adult venomous snakes. However, due to logistical constraints, antivenoms are produced using adult venoms in immunising mixtures, possibly resulting in limited neutralisation of juvenile snake venoms. Daboia russelii is one of the leading causes of snakebite death across South Asia. Its venom is potently procoagulant, causing stroke in prey animals but causing in humans consumptive coagulopathy-a net anticoagulant state-and sometimes death resulting from hemorrhage. In this in vitro study, we compared the venom activity of-and antivenom efficacy against-six 2-week-old D. russelii relative to that of their parents. Using a coagulation analyser, we quantified the relative coagulotoxicity of these venoms in human, avian, and amphibian plasma. The overall potency on human plasma was similar across all adult and neonate venoms, and SII (Serum Institute of India) antivenom was equipotent in neutralising these coagulotoxic effects. In addition, all venoms were also similar in their action upon avian plasma. In contrast, the neonate venoms were more potent on amphibian plasma, suggesting amphibians make up a larger proportion of neonate diet than adult diet. A similar venom potency in human and avian plasmas but varying selectivity for amphibian plasma suggests ontogenetic differences in toxin isoforms within the factor X or factor V activating classes, thereby providing a testable hypothesis for future transcriptomics work. By providing insights into the functional venom differences between adult and neonate D. russelii venoms, we hope to inform clinical treatment of patients envenomated by this deadly species and to shed new light on the natural history of these extremely medically important snakes.

Capillary leak syndrome induced by the venoms of Russell's Vipers (Daboia russelii and Daboia siamensis) from eight locales and neutralization of the differential toxicity by three snake antivenoms

Snakebite envenomation caused by the Western and Eastern Russell's Vipers (Daboia russelii and Daboia siamensis) may potentially induce capillary leak syndrome (CLS), while the use of antivenom in treating this has not been well examined. This study investigated the CLS-inducing toxicity of Russell's Viper venoms from various sources and examined the neutralization activity of regionally available antivenoms, using a newly devised mouse model. D. russelii venoms demonstrated a more consistent vascular leakage activity (76,000-86,000 CLS unit of vascular leak index, a function of the diameter and intensity of Evans Blue dye extravasation into dermis) than D. siamensis venoms (33,000-88,000 CLS unit). Both species venoms increased hematocrits markedly (53-67%), indicating hemoconcentration. Regional antivenoms (DsMAV-Thailand, DsMAV-Taiwan, VPAV-India) preincubated with the venoms effectively neutralized the CLS effect to different extents. When the antivenoms were administered intravenously post-envenomation (challenge-rescue model), the neutralization was less effective, implying that CLS has a rapid onset that preceded the neutralizing activity of antivenom, and/or the antivenom has limited biodistribution to the venom's inoculation site. In conclusion, Russell's Viper venoms of both species from various locales induced CLS in mice. Antivenoms generally had limited efficacy in neutralizing the CLS effect. Innovative treatment for venom-induced CLS is needed.

Potential of herbal cocktail of medicinal plant extracts against 'big four' snake venoms from India

Background

Venomous snake bites cause acute medical emergencies and are fatal. India accounts for large proportion of snake-bite deaths globally. Medically important ‘BIG FOUR’ snakes of India are Bungarus caeruleus (krait), Naja naja (cobra), Echis carinatus (saw-scaled viper) and Daboia russelii (Russell's viper). Polyherbal formulations have been proved to be effective in treatment of diseases than a single formulation.

Objective(s)

To evaluate aqueous ethanolic extract cocktail of Azadirachata indica, Butea monosperma, Citrus limon, Clerodendrum serratum and Areca catechu for antidote potential against BIG FOUR venoms in ex vivo and in vivo model.

Materials and methods

Anti-hemorrhagic and venom neutralization studies were performed in seven-day old chick embryo model for ex vivo studies. In vivo studies were performed using male Swiss albino mice for antivenom potential of herbal cocktail by performing anti-edematic, anti-hemorrhagic, anti-myotoxic activity, and venom neutralization.

Results

Herbal cocktail exhibited differential venom inhibition potential against four venoms tested. Hemorrhagic activity was completely neutralized by the herbal cocktail; myotoxic activities of krait and Russell's viper venom were neutralized; while anti-edematic activity was observed for krait and cobra venom. Herbal cocktail completely neutralized venom lethality (3∗LD₅₀) of krait and saw-scaled viper venom.

Conclusion

Inhibitions of various venom components of all four venoms suggests presence of phytochemicals in herbal cocktail with therapeutic properties. Further studies would help in the development of a formulation as a first-aid towards treatment of snake bite victims.

Proximity between humans and a highly medically significant snake, Russell's viper, in a tropical rural community

Snakebite envenoming is a major neglected tropical health issue. The high incidence of snakebites in tropical rural communities suggests that venomous snakes and people are often in proximity but quantitative evidence is lacking. I used radio-telemetry on a population of Russell's vipers (Daboia russelii), one of the most medically important snakes in the world, to quantify proximity between this venomous snake and people and estimate susceptibility to snakebite envenoming in India. I observed people ≤50 m of a radio-equipped viper in ~17% of 2,066 snake relocations. People were more frequently observed in proximity to Russell's vipers in January and July compared to March, but all other contrasts were statistically similar. This pattern indicates that snakebite incidence, which peaks in summer in the study area, is not particularly linked to the encounter frequency between people and vipers. However, consistent with epidemiological data plantation workers were the most at-risk part of the population. By integrating information about the locations of humans and snakes in space and time, this pioneering research highlights the need to include snake ecology into the study of the human-venomous-snake conflict, and provides a model approach to help mitigate the burden caused by venomous snakes in the rural Tropics.

Sodium oleate, arachidonate, and linoleate enhance fibrinogenolysis by Russell's viper venom proteinases and inhibit FXIIIa; a role for phospholipase A2 in venom induced consumption coagulopathy

Life-threatening symptoms produced by Russell's viper (RV, Daboia russelii) envenomation result largely from venom induced consumption coagulopathy (VICC). VICC is thought to be mediated to a large degree by venom serine and metalloproteinases, as well as by snake venom phospholipase A2 (svPLA2), the most abundant constituent of RV venom (RVV). The observation that the phenolic lipid anacardic acid markedly enhances proteolytic degradation of fibrinogen by RVV proteinases led us to characterize the chemical basis of this phenomenon with results indicating that svPLA2 products may be major contributors to VICC. RESULTS: Of the chemical analogs tested, the anionic detergents sodium dodecyl sulfate, sodium deoxycholate, N-lauryl sodium sarcosine, and the sodium salts of the fatty acids arachidonic, oleic and to a lesser extend linoleic acid were able to enhance fibrinogenolysis by RVV proteinases. Enhanced Fibrinogenolysis (EF) was observed with various venom size exclusion fractions containing different proteinases, and also with trypsin, indicating that conformational changes of the substrate and increased accessibility of otherwise cryptic cleavage sites are likely to be responsible for EF. In addition to enhancing fibrinogenolysis, sodium arachidonate and oleate were found to partially inhibit thrombin induced, factor XIIIa (FXIIIa) mediated ligation of fibrin chains. In clotting experiments with fresh blood RVV was found to disrupt normal coagulation, leading to small, partial clot formation, whereas RVV pretreated with the PLA2 inhibitor Varespladib induced rapid and complete clot formation (after 5 min) compared to blood alone. CONCLUSION: The observations that fatty acid anions and anionic detergents induce conformational changes that render fibrin(ogen) more susceptible to proteolysis by RVV proteinases and that RVV-PLA2 activity (which produces FFA) is required to render blood incoagulable in clotting experiments with RVV indicate a mechanism by which the activity of highly abundant RVV-PLA2 promotes degradation and depletion of fibrin(ogen) resulting in incoagulable blood seen following RVV envenomation (VICC).

Analysis of wound exudates reveals differences in the patterns of tissue damage and inflammation induced by the venoms of Daboia russelii and Bothrops asper in mice

Clinical manifestations of envenomings by bites of the viperid snakes Bothrops asper and Daboia russelii show marked differences. Both venoms elicit the typical effects induced by viperid venoms (local tissue damage, bleeding, coagulopathies, shock). In addition, envenomings by D. russelii are characterized by a high incidence of acute kidney injury and by systemic capillary leak syndrome. The present investigation aimed to compare the local pathological and inflammatory events induced by the intramuscular injection of these venoms in a mouse model. B. asper venom induced stronger local hemorrhage, whereas D. russelii venom caused a higher extent of myonecrosis, and both venoms induced inflammation. Exudates collected from the site of tissue damage showed higher proteolytic activity in the case of samples from B. asper venom-treated mice. This activity was abrogated by antivenoms, indicating that it is the result of the action of venom proteinases. In addition, an increase in matrix metalloproteinases (MMPs) over time was detected in exudates induced by both venoms. Proteome analysis of exudates revealed higher abundance of extracellular matrix (ECM)-derived protein fragments in samples collected from B. asper venom-injected mice, whereas those from D. russelii venom-injected animals had higher amounts of intracellular proteins. Analysis of the subproteome of inflammatory mediators in exudates showed various patterns of change over time. Some mediators peaked at 180 min and decreased afterwards, whereas others increased and remained elevated during the 360 min observation period. Interestingly, various mediators (MIP-1α, MIP-1β, KC, MIP-2, GM-CSF, VEGF, and LIX) increased and then decreased in the case of B. asper venom, while they remained elevated at 360 min in the case of D. russelii venom. Our findings show that these venoms induce a different pattern of local tissue damage and suggest that the venom of D. russelii induces a more sustained inflammatory reaction, an observation that may have implications for the pathophysiology of envenomings.

Evaluation of cultivable aerobic bacterial flora from Russell's viper (Daboia russelii) oral cavity

Snake mouths contain a wide range of bacteria. Identifying these bacteria in snakes is very important to obtain an understanding of the etiological agents of secondary infections that may result from accidents during handling and/or snake bites. The present study aims to determine the pattern of oral bacterial flora of nine healthy Russell's vipers (Daboia russelii), and their susceptibility to common antibiotics. A total of 94 isolates were obtained in pure form, which demonstrated noticeable colony characteristics and which were further studied with several biochemical tests. The strains that showed distinctive colonies, morphology and biochemical parameters were additionally subjected to phylogenetic characterization using 16S rRNA gene sequences. Furthermore, all these isolates were studied for antibiotic susceptibility. The oral cavity of the Russell's viper harbors a wide range of pathogenic bacteria, including Gram-negative genera: Proteus sp., Pseudomonas sp., Salmonella sp., Providencia sp., Alcaligenes sp., Morganella sp., as well as E. coli, and Gram-positive genera: Bacillus and Enterococcus sp., Staphylococcus sp. and Lysinobacillus sp. Most of the isolates were resistant to antibiotics viz. penicillin, Amoxyclav, oxacillin, methicillin and streptomycin while sensitive towards imipenem, amikacin, norfloxacin, gatifloxacin, ciprofloxacin, gentamicin, tetracycline, chloramphenicol and azithromycin. The present study documents diverse bacteria predominant in the oral cavity of Daboia russelii and studied their antibiotic susceptibilities.

Clinico-epidemiology and management of Russell's viper (Daboia russelii) envenoming in dogs in Sri Lanka

INTRODUCTION

Russell's viper envenoming in dogs is a significant problem in Sri Lanka. The current study focused on investigating clinical profile, laboratory findings of three selected tests and to develop a treatment strategy with Indian polyvalent Anti-Venom Serum (AVS). It was also intended to report adverse effects and complications caused by both Russell's viper venom (RVV) and AVS in Russell's Viper (RV) envenomed dogs.

OBJECTIVE

To evaluate and report the clinical manifestations, to find out the minimum effective vials of AVS and to record AVS induced adverse reactions of RV envenoming in dogs.

MATERIALS AND METHODS

A prospective study was conducted on Russell's viper bitten dogs (n = 65) admitted to the Veterinary Teaching Hospital (VTH) in Sri Lanka. Indian polyvalent AVS was used to treat all the envenomed dogs. The number of vials of AVS that was administered to a patient was decided upon by a second degree polynomial model with a number of vials of AVS in the X axis verses Prothrombine Time (PT), Activated Partial Thromboplastine Time (aPTT) and Clotting Time (CT) in the Y axis respectively.

RESULTS

Varying degrees of pain were exhibited by all the victim dogs. Mild swelling and necrosis at the site of bite was seen in 54% (n = 35) and 37% (n = 24) of dogs respectively. Prolonged values of, PT, aPTT and CT were seen from all the RV envenomed dogs. The mean leukocyte count in these dogs was 39.79 × 103/μL (normal range; 4-20 × 103/μL) (IQR:29.05 × 103/μL-45.92 × 103/μL). Statistical analysis showed that the initial vials of 7 AVS would be the minimum required vials. Therefore, a range of 6-15 AVS vials in total were administered to these dogs and in 7.6% (n = 5) of dogs, the results of PT, aPTT and CT became normal with 6 AVS vials at 32-97 minutes. Acute Renal Failure (ARF) was detected from 29% (n = 19) of dogs as a complication.

CONCLUSIONS

Systemic clinical signs of haemorrhagic lesions, cardio respiratory toxicities were common in Russell's viper envenomed dogs. Initially 6 vials of AVS must be administered. AVS induced reactions were reported commonly. Russell's viper envenoming was found to be lethal in dogs.

Purification and partial characterization of an anticoagulant PLA2 from the venom of Indian Daboia russelii that induces inflammation through upregulation of proinflammatory mediators

The present study describes the purification and partial characterization of a basic anticoagulant PLA2 enzyme named as Rv(i) PLA2 from the venom of Indian Daboia russelii. The molecular mass of the protein was found to be 13,659.65 Da, and peptide mass fingerprinting revealed that it belongs to group II PLA2 family. The peptide sequence showed similarity to uncharacterized basic PLA2 enzyme having an accession no. of P86368 reported from Sri Lankan D. russelii. Rv(i) PLA2 exhibited strong phospholipase A2 and anticoagulant activity. It also induced expression of COX-2 and TNF-α mRNA in a dose-dependent manner in phorbol 12-myristate 13-acetate differentiated THP-1 cells, which play a crucial role during inflammation. Chemical modification of His residue in Rv(i) PLA2 with p-bromophenacyl bromide abolished the enzymatic, anticoagulant, and inflammatory activities. The result indicates that the catalytic site of Rv(i) PLA2 might play a vital role in inducing inflammation at the bite site during D. russelii envenomation.

Characterization of Daboia russelii and Naja naja venom neutralizing ability of an undocumented indigenous medication in Sri Lanka

Background

Indigenous medicinal practice in Sri Lanka talks about powerful compounds extracted from native plants for treating venomous snake bites which are hardly documented in literature but are used by the indigenous doctors for thousand years.

Objective

We screened the neutralizing ability of a herbal preparation practiced in indigenous medicine of Sri Lanka, consisting of Sansevieria cylindrica, Jatropha podagrica and Citrus aurantiifolia, for its ability to neutralize venom toxins of Naja naja (Common Cobra) and Daboia russelii (Russell's viper).

Materials and methods

The venom toxicity was evaluated using a 5-day old chicken embryo model observing the pathophysiology and the mortality for six hours, in the presence or absence of the herbal preparation. The known toxin families to exist in snake venom, such as Phospholipase A₂, Snake venom Metalloprotease, were evaluated to understand the mechanism of venom neutralizing ability of the herbal preparation.

Results

The LD₅₀ of D. russelii venom, as measured using the 5-day old chicken embryo model, was 4.8 ± 0.865 ug (R² = 84.8%, P = 0.079). The pre-incubation of venom with the herbal preparation increased the LD₅₀ of D. russelii venom to 17.64 ± 1.35 μg (R² = 81.0%, P = 0.100), showing a clear neutralizing action of D. russelii venom toxicity by the herbal medicine. Whereas the pre-incubation of venom with the 1× venom neutralizing dose of commercially available polyvalent anti-venom serum shifted the LD₅₀ venom only up to 5.5 ± 1.35 μg (R² = 98.8%, P = 0.069). In the presence of the herbal preparation, Phospholipase A₂ activity of D. russelii venom was significantly reduced from 9.2 × 10⁻³ mM min⁻¹ to 8.0 × 10⁻³ mM min⁻¹ and that of N. naja from 2.92 × 10⁻² mM min⁻¹ to 0.188 × 10⁻² mM min⁻¹. Further, the pre-incubation of N. naja venom with the herbal preparation significantly reduced its Metalloprotease activity from 0.069 units min⁻¹ to 0.019 units min⁻¹.

Conclusion

The herbal preparation shows a clear neutralizing action against the toxicities of D. russelii and N. naja venoms demonstrating the potential to be used as a plant based antidote for snake envenomation.

Ischemic brain infarcts and intracranial haemorrhages following Russell's viper (Daboia russelii) bite in Sri Lanka

Snakebite is an important medical problem in Sri Lanka. Of the deadly venomous snakes, Russell's viper (Daboia russelii) is widely distributed and responsible for most of the fatalities of snakebite in the country. It is not uncommon to see atypical manifestations in Russell's viper bite. We report the events of intracranial haemorrhages and multiple ischemic brain infarcts following Russell's viper (Daboia russelii) bite of a previously healthy 43-years-old male who succumbed to envenoming.

Development of a new polyspecific antivenom for snakebite envenoming in Sri Lanka: Analysis of its preclinical efficacy as compared to a currently available antivenom

A new whole IgG, freeze-dried, polyspecific antivenom was prepared from the plasma of horses immunized with the venoms of the snakes Daboia russelii, Echis carinatus, Hypnale hypnale, and Naja naja from Sri Lanka. The preclinical neutralizing ability of this antivenom against several toxic and enzymatic activities of these four venoms was analyzed, and compared with that of a batch of VINS antivenom (India) being currently used in Sri Lanka. The activities tested were: lethality, hemorrhagic, in vitro coagulant, proteinase and phospholipase A₂. Both antivenoms neutralized, to a different extent, these activities of the venom of D. russelii, E. carinatus, and N. naja. In general, the polyspecific Sri Lankan antivenom was more effective than the Indian antivenom in the neutralization of the venoms of D. russelii and E. carinatus, whereas the Indian antivenom showed a higher efficacy against the venom of N. naja. Regarding H. hypnale, the new Sri Lankan antivenom was effective in the neutralization of all activities tested, whereas the Indian antivenom neutralized lethality but not hemorrhagic, coagulant, proteinase and PLA₂ activities, in agreement with the fact that this venom is not included in the immunization mixture for this antivenom. Results suggest that the new polyspecific Sri Lankan antivenom has a satisfactory preclinical neutralizing profile and compares favorably with the Indian antivenom. This is ready to be tested in a clinical trial to evaluate its efficacy and safety in human victims of snakebite envenomings by D. russelii, E. carinatus and H. hypnale in Sri Lanka.

Neurotoxicity in Russell's viper (Daboia russelii) envenoming in Sri Lanka: a clinical and neurophysiological study

CONTEXT

Russell's viper is more medically important than any other Asian snake, due to number of envenoming's and fatalities. Russell's viper populations in South India and Sri Lanka (Daboia russelii) cause unique neuromuscular paralysis not seen in other Russell's vipers.

OBJECTIVE

To investigate the time course and severity of neuromuscular dysfunction in definite Russell's viper bites, including antivenom response.

METHODOLOGY

We prospectively enrolled all patients (>16 years) presenting with Russell's viper bites over 14 months. Cases were confirmed by snake identification and/or enzyme immunoassay. All patients had serial neurological examinations and in some, single fibre electromyography (sfEMG) of the orbicularis oculi was performed.

RESULTS

245 definite Russell's viper bite patients (median age: 41 years; 171 males) presented a median 2.5 h (interquartile range: 1.75-4.0 h) post-bite. All but one had local envenoming and 199 (78%) had systemic envenoming: coagulopathy in 166 (68%), neurotoxicity in 130 (53%), and oliguria in 19 (8%). Neurotoxicity was characterised by ptosis (100%), blurred vision (93%), and ophthalmoplegia (90%) with weak extraocular movements, strabismus, and diplopia. Neurotoxicity developed within 8 h post-bite in all patients. No bulbar, respiratory or limb muscle weakness occurred. Neurotoxicity was associated with bites by larger snakes (p < 0.0001) and higher peak serum venom concentrations (p = 0.0025). Antivenom immediately decreased unbound venom in blood. Of 52 patients without neurotoxicity when they received antivenom, 31 developed neurotoxicity. sfEMG in 27 patients with neurotoxicity and 23 without had slightly elevated median jitter on day 1 compared to 29 normal subjects but normalised thereafter. Neurological features resolved in 80% of patients by day 3 with ptosis and weak eye movements resolving last. No clinical or neurophysiological abnormality was detected at 6 weeks or 6 months.

CONCLUSION

Sri Lankan Russell's viper envenoming causes mild neuromuscular dysfunction with no long-term effects. Indian polyvalent antivenom effectively binds free venom in blood but does not reverse neurotoxicity.

IgE antibodies, FcεRIα, and IgE-mediated local anaphylaxis can limit snake venom toxicity

BACKGROUND

Type 2 cytokine-related immune responses associated with development of antigen-specific IgE antibodies can contribute to pathology in patients with allergic diseases and to fatal anaphylaxis. However, recent findings in mice indicate that IgE also can enhance defense against honeybee venom.

OBJECTIVE

We tested whether IgE antibodies, IgE-dependent effector mechanisms, and a local anaphylactic reaction to an unrelated antigen can enhance defense against Russell viper venom (RVV) and determined whether such responses can be influenced by immunization protocol or mouse strain.

METHODS

We compared the resistance of RVV-immunized wild-type, IgE-deficient, and Fcer1a-deficient mice after injection of a potentially lethal dose of RVV.

RESULTS

A single prior exposure to RVV enhanced the ability of wild-type mice, but not mice lacking IgE or functional FcεRI, to survive challenge with a potentially lethal amount of RVV. Moreover, IgE-dependent local passive cutaneous anaphylaxis in response to challenge with an antigen not naturally present in RVV significantly enhanced resistance to the venom. Finally, we observed different effects on resistance to RVV or honeybee venom in BALB/c versus C57BL/6 mice that had received a second exposure to that venom before challenge with a high dose of that venom.

CONCLUSION

These observations illustrate the potential benefit of IgE-dependent effector mechanisms in acquired host defense against venoms. The extent to which type 2 immune responses against venoms can decrease pathology associated with envenomation seems to be influenced by the type of venom, the frequency of venom exposure, and the genetic background of the host.

Functional venomics of the Sri Lankan Russell's viper (Daboia russelii) and its toxinological correlations

The venom proteome (venomics) of the Sri Lankan Daboia russelii was elucidated using 1D SDS PAGE nano-ESI-LCMS/MS shotgun proteomics. A total of 41 different venom proteins belonging to 11 different protein families were identified. The four main protein families are phospholipase A2 (PLA2, 35.0%), snaclec (SCL, 22.4%, mainly platelet aggregation inhibitors), snake venom serine proteinase (SVSP, 16.0%, mainly Factor V activating enzyme) and snake venom metalloproteinase (SVMP, 6.9%, mainly heavy chain of Factor X activating enzyme). Other protein families that account for more than 1% of the venom protein include l-amino acid oxidase (LAAO, 5.2%), Kunitz-type serine proteinase inhibitor (KSPI, 4.6%), venom nerve growth factor (VNGF. 3.5%), 5'-nucleotidase (5'NUC, 3.0%), cysteine-rich secretory protein (CRISP, 2.0%) and phosphodiesterase (PDE, 1.3%). The venom proteome is consistent with the enzymatic and toxic activities of the venom, and it correlates with the clinical manifestations of Sri Lankan D. russelii envenomation which include hemorrhage, coagulopathy, renal failure, neuro-myotoxicity and intravascular hemolysis. The venom exhibited remarkable presypnatic neurotoxicity presumably due to the action of basic PLA2 in high abundance (35.0%). Besides, SCLs, Factor X activating enzymes (SVMPs), SVSPs, and LAAOs are potential hemotoxins (50.5%), contributing to coagulopathy and hemorrhagic syndrome in Sri Lankan D. russelii envenomation.

SIGNIFICANCE

The study demonstrated the proteomic profile of the Sri Lankan Russell's viper venom, unraveling its complex composition of toxins and correlations with major toxic activities. The types, numbers, and relative abundances of toxins were reported. The venom content was dominated by the neurotoxic basic phospholipases A2 (>30% of total protein abundance) and several hemotoxic or coagulopathic protein families (approximately 50% in total). The proteome correlates with the functional and toxinological characterizations of the venom, and reflects the pathophysiological effects of envenomation by the Sri Lankan Russell's viper. The venom proteomics may serve to propel the understanding on pathogenesis and treatment strategy for envenomation by this viper in Sri Lanka. The enriched database contributed by the proteomic findings will be useful for comparing venom variations among Russell's vipers from different geographical areas.

Studies on neutralizing effect of Ophiorrhiza mungos root extract against Daboia russelii venom

ETHNOPHARMACOLOGICAL RELEVANCE

The folklore or traditional therapy in southern India widely utilizes a plethora of local herbs to treat the patients challenged with snake venom. Despite the widespread implementation of antisera therapy, the local population of the country still relies on this century's old medicinal formulas mainly due to the cost effectiveness, lesser side effects and also its cultural acceptability. The present study aims to validate the neutralizing ability of one such traditionally acclaimed antidote Ophiorrhiza mungos root extract against Russell's viper (Daboia russelii) venom in the early developing chick embryos.

MATERIALS AND METHODS

The disc impregnated with venom, root extract or the combination of both was placed on the yolk sac membrane preferably over the anterior blood vessel of 6th day chick embryo. The neutralization/inhibition of venom-induced lethality or hemorrhage was achieved by incubating venom and extract before being applied to the embryo. The membrane stabilizing properties of root extract was estimated by HRBC lysis method. The preliminary phytochemical analysis was done to assess the phyto constituents in the root extract.

RESULTS

The LD50 of Russell's viper venom in 6th day chick embryo was found to be 3 μg/μl. The neutralising effect of root extract was achieved by pre-incubating venom with various concentrations of extract and at the concentration of 10 μg/μl, 100% recovery of embryos was observed after 6h of incubation. Higher concentration of root extract showed remarkable results by completely abolishing traces of hemorrhagic lesions induced by viper venom.

CONCLUSIONS

The above observations confirmed that the root extract of Ophiorrhiza mungos possess potent anti snake venom neutralizing compounds, which inhibit the activity of viper venom. The chick embryo, a new insensate model used in the present study is significant in venom research as it reduces the ruthless suffering of higher mammalian experimental models.

Synergistically acting PLA₂: peptide hemorrhagic complex from Daboia russelii venom

Snake venoms are complex mixture of enzymatic and non-enzymatic proteins. Non-covalent protein-protein interaction leads to protein complexes, which bring about enhanced pharmacological injuries by their synergistic action. Here we report identification and characterization of a new Daboia russelii hemorrhagic complex I (DR-HC-I) containing phospholipase A₂ (PLA₂) and non-enzymatic peptide. DR-HC-I was isolated from the venom of D. russelii by CM-Shepadex-C25 and gel permeation chromatography. Individual components were purified and identified by RP-HPL chromatography, mass spectrometry and N-terminal amino acid sequencing. DR-HC-I complex was lethal to mice with the LD₅₀ dose of 0.7 mg/kg body weight with hemorrhagic and neurotoxic properties. DR-HC-I complex consists of non-hemorrhagic PLA₂ and neurotoxic non-enzymatic peptide. The non-enzymatic peptide quenched the intrinsic fluorescence of PLA₂ in a dose dependent manner, signifying the synergistic interaction between two proteins. PLA₂ and peptide toxin in a 5:2 M ratio induced skin hemorrhage in mice with MHD 20 μg. However, addition of ANS (1-Anilino-8-naphthalene sulfonate) to DR-HC-I complex inhibited skin hemorrhagic effect and also synergic interaction. But there was no impact on PLA₂ due to this synergistic interaction, and indirect hemolytic or plasma re-calcification activity. However, the synergistic interaction of PLA₂ and non-enzymatic peptide contributes to the enhanced venom-induced hemorrhage and toxicity of Daboia russellii venom.