Characterization of three edema-inducing phospholipase A2 enzymes from habu (Trimeresurus flavoviridis) venom and their interaction with the alkaloid aristolochic acid

Inhibitors and activators for myotoxic phospholipase A2-like toxins from snake venoms - A structural overview

Snakebite envenomations result in acute and chronic physical and psychological health effects on their victims, leading to a substantial socio-economic burden in tropical and subtropical countries. Local necrosis is one of the serious effects caused by envenomation, primarily induced by snake venoms from the Viperidae family through the direct action of components collectively denominated as myotoxins, including the phopholipase A2-like (PLA2-like) toxins. Considering the limitations of antivenoms in preventing the rapid development of local tissue damage caused by envenomation, the use of small molecule therapeutics has been suggested as potential first-aid treatments or as adjuvants to antivenom therapy. In this review, we provide an overview of the structural interactions of molecules exhibiting inhibitory activity toward PLA2-like toxins. Additionally, we discuss the implications for the myotoxic mechanism of PLA2-like toxins and the molecules involved in their activation, highlighting key differences between activators and inhibitors. Finally, we integrate all these results to propose a classification of inhibitors into three different classes and five sub-classes. Taking into account the structural and affinity information, we compare the different inhibitors/ligands to gain a deeper understanding of the structural basis for the effective inhibition of PLA2-like toxins. By offering these insights, we aim to contribute to the search for new and efficient inhibitor molecules to complement and improve current therapy by conventional antivenoms.

Naja naja snake venom-induced local toxicities in mice is by inflammasome activation

Snake bite envenomation causes tissue damage resulting in acute and chronic inflammatory responses. Inflammasome activation is one of the factors involved in tissue damage in a mouse model of snake envenomation. The present study examines the potency of Indian Big Four snake venoms in the activation of inflammasome and its role in local and systemic tissue toxicity. Among Indian Big Four snake venoms, Naja naja venom activated NLRP3 inflammasome in mouse macrophages. Activation of NLRP3 inflammasome was also observed in mouse foot paw and thigh muscle upon administration of N. naja venom. Intraperitoneal administration of N. naja venom cause systemic lung damage showed activation of NLRP3 inflammasome. Treatment with MCC950, a selective NLRP3 inflammasome inhibitor effectively inhibited N. naja venom-induced activation of caspase-1 and liberation of IL-1β in macrophages. In mice, MCC950 partially inhibited the activation of NLRP3 inflammasome in N. naja venom administered foot paw and thigh muscle. In conclusion, the present data showed that inflammasome is one of the host responses involved in N. naja snake venom-induced toxicities. The inhibition of inflammasome activation will provide new insight into better management of snake bite-induced local tissue damage.

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.

Kenaf Seed Cysteine Protease (KSCP) Inhibits the Intrinsic Pathway of the Blood Coagulation Cascade and Platelet Aggregation

BACKGROUND

Thrombosis is the key event that obstructs the flow of blood throughout the circulatory system, leading to stroke, myocardial infarction and severe cardiovascular complications. Currently, available antithrombotic drugs trigger several life-threatening side effects.

INTRODUCTION

Antithrombotic agents from natural sources devoid of adverse effects are grabbing high attention. In our previous study, we reported the antioxidant, anticoagulant and antiplatelet properties of kenaf seed protein extract. Therefore, in the current study, purification and characterization of cysteine protease from kenaf seed protein extract responsible for potential antithrombotic activity was undertaken.

METHODS

Purification of KSCP (Kenaf Seed Cysteine Protease) was carried out using gel permeation and ion exchange column chromatography. The purity of the enzyme was evaluated by SDS PAGE (Sodium Dodecyl-Sulfate Polyacrylamide Gel Electrophoresis). RP-HPLC (Reverse Phase High-Performance Liquid Chromatography), MALDI-TOF (Matrix-Assisted Laser Desorption Ionization Time-Of-Flight) and CD (Circular Dichroism techniques) were employed for its characterization. Proteolytic, fibrinolytic and kinetic study was done using spectroscopy. Plasma recalcification time, Prothrombin Time (PT), Thrombin clotting time (TCT), Activated Partial Thromboplastin Time (APTT), bleeding time and platelet aggregation studies were carried out for antithrombotic activity of KSCP.

RESULT

A single sharp band of KSCP was observed under both reduced and non-reduced conditions, having a molecular mass of 24.1667kDa. KSCP was found to contain 30.3% helix turns and 69.7% random coils without a beta-pleated sheet. KSCP digested casein and fibrin, and its activity was inhibited by iodoacetic acid (IAA). KSCP was optimally active at pH 6.0 at the temperature of 40°C. KSCP exhibited anticoagulant properties by interfering in the intrinsic pathway of the blood coagulation cascade. Furthermore, KSCP dissolved both whole blood and plasma clots and platelet aggregation.

CONCLUSION

KSCP purified from kenaf seed extract showed antithrombotic potential. Hence, it could be a better candidate for the management of thrombotic complications.

Insight into the Toxicological and Pathophysiological Effects of Moroccan Vipers' Venom: Assessing the Efficacy of Commercial Antivenom for Neutralization

Morocco is one of the richest countries in biodiversity in the Mediterranean region, especially in its ophidian fauna. In total, there are eight species of venomous snakes, with seven belonging to the Viperidae family, responsible for 67.2% of severe envenomation cases in the country. Cerastes cerastes, Daboia mauritanica and Bitis arietans are considered among the most venomous vipers whose bites cause high levels of morbidity, disability or mortality. Despite their wide distribution in the kingdom, the incidence of these snakebites remains poorly understood and largely underestimated. Moreover, intraspecific variations in the venom composition significantly affect the effectiveness of antivenoms. Due to the unavailability of locally produced antivenoms, we evaluated the efficacy of Inoserp-MENA, the only available antivenom in Morocco, against C. cerastes, D. mauritanica and B. arietans. First, we conducted a comprehensive characterization of these venoms, including an LD₅₀ test to examine their toxicity and SDS-PAGE as a technique to analyze the enzymes responsible for biological activities, such as hemorrhagic and edematous activities and myotoxicity, which generate physiopathological effects in the skin, paws and muscles of envenomed mice. Then, we assessed the ability of Inoserp-MENA antivenom to neutralize the toxic activities of Moroccan vipers. Our results indicate that the venom of C. cerastes, D. mauritanica and B. arietans are toxic, causing severe alterations such as edema, myotoxicity, myonecrosis and significant hemorrhages with the formation of hemorrhagic foci. C. cerastes venom is more dangerous in terms of lethality and hemorrhages, while B. arietans venom is more edematous. The effects of C. cerastes venom were effectively neutralized, but Inoserp-MENA antivenom failed to protect mice against the toxic effects induced by B. arietans and D. mauritanica venom. The study reveals alarming shortcomings in the effectiveness of the current commercially available antivenom's dosage and neutralization capabilities, highlighting the urgent need to develop a region-specific viper envenomation therapy.

Pennisetum glaucum Protein Extract Protects RBC, Liver, Kidney, Small Intestine from Oxidative Damage and Exhibits Anticoagulant, Antiplatelet Activity

High level of exogenous ROS in the circulation affects RBC membrane integrity which facilitates the generation of endogenous RBC ROS, implicated in series of physiological changes primarily associated with thrombosis and vital tissue damage. Although, Pennisetum glaucum (pearl millet) stores abundance of proteins, their therapeutic potential is least explored. Thus, the purpose of this study is to examine the role of Pennisetum Glaucum Protein Extract (PGE) on oxidative stress induced cell/tissue damage and thrombosis. In this investigation, protein characterization was done by using SDS-PAGE, Native-PAGE, PAS-staining and HPLC. In-vitro oxidative stress was induced in RBC using sodium nitrite. While, in-vivo oxidative stress was induced in experimental rats using diclofenac. Stress markers and biochemical parameters were evaluated. Role of PGE on thrombosis was assessed by using, in-vitro plasma recalcification time, activated partial thromboplastin time, prothrombin time, mouse tail bleeding time (In-vivo) and platelet aggregation. PGE revealed varied range of molecular weight proteins on SDS-PAGE. PGE normalized the sodium nitrite induced oxidative damage of RBC and diclofenac induced oxidative damage in liver, kidney and small intestine. PGE exhibited anticoagulant effect by increasing the coagulation time of both PRP and PPP and mouse tail bleeding time. Furthermore, PGE prolonged the clotting time of only APTT but did not affect PT. PGE inhibited agonists ADP and epinephrine induced platelet aggregation. Our findings suggest, PGE could be a better contender in the management of oxidative stress and its associated diseases.

ABBREVIATIONS

PGEPennisetum Glaucum protein ExtractAPPTActivated Partial Thromboplastin TimePTProthrombin TimeROSReactive Oxygen SpeciesPRPPlatelet Rich PlasmaPPPPlatelet Poor PlasmaSDS-PAGESodium Dodecyl Sulfate-Polyacrylamide Gel ElectrophoresisPASPeriodic Acid-schiff StainingODOptical DensityINRInternational Normalized RatioPBSPhosphate Buffered SalineSODSuperoxide DismutaseTCATrichloro Acetatic AcidDTNBDi-Thio-bis-NitroBenzoic acidSGOTSerum Glutamate Oxaloacetate TransaminaseSGPTSerum Glutamate Pyruvate TransaminaseALPAlkaline PhosphataseDFCDiclofenacSylSilymarinMEDMinimum Edema DoseMHDMinimum Hemorrhagic Dose.

Antioxidant and Antithrombotic Activities of Kenaf Seed (Hibiscus cannabinus) Coat Ethanol Extract in Sprague Dawley Rats

Oxidative stress has been implicated in deadly lifestyle diseases, and antioxidants from plant sources are the primary option in the treatment regime. Kenaf seeds are the storehouse of potential natural antioxidant phytoconstituents. Perhaps, none of the studies documented the phytoconstituents and their antioxidant potential from Kenaf seed coat so far. Thus, the current study focuses on exploring the protective effect of Kenaf Seed Coat Ethanol Extract (KSCEE) against sodium nitrite and diclofenac-induced oxidative stress in vitro (red blood cell and platelets model) and in vivo (female Sprague Dawely rat's model) along with the antithrombotic activity. The infrared spectrophotometry data showed the heterogeneous functional groups (CH, OH, C = C, C = C-C) and aromatic rings. Reverse phase high-performance liquid chromatography and gas chromatography-mass spectrometry chromatogram of KSCEE also evidenced the presence of several phytochemicals. KSCEE displayed about 76% of DPPH scavenging activity with an IC₅₀ value of 34.94 µg/ml. KSCEE significantly (***p < 0.001) normalized the stress markers such as lipid peroxidation, protein carbonyl content, superoxide dismutase, and catalase in sodium nitrite and diclofenac-induced oxidative stress in RBC, platelets, liver, kidney, and small intestine, respectively. Furthermore, KSCEE was found to protect the diclofenac-induced tissue destruction of the liver, kidney, and small intestine obtained from seven groups of female Sprague Dawely rats. KSCEE delayed the clotting time of platelet-rich plasma and platelet-poor plasma and activated partial thromboplastin time, suggesting its anticoagulant property. In addition, KSCEE also exhibited antiplatelet activity by inhibiting both adenosine diphosphate and epinephrine-induced platelet aggregation. In conclusion, KSCEE ameliorates the sodium nitrite and diclofenac-induced oxidative stress in red blood cells, platelets, and experimental animals along with antithrombotic properties.

Utilization of gallic acid to inhibit some toxic activities caused by Bothrops jararaca or B. jararacussu snake venoms

Snake bite envenoming is a serious public health issue, affecting thousands of people worldwide every year, especially in rural communities of tropical and subtropical countries. Injection of venom into victims may cause hemorrhaging, blood coagulation imbalance, inflammation, pain, edema, muscle necrosis, and eventually, death. The official validated treatment recommended by governments is the administration of antivenom that efficiently prevents morbidity and mortality. However, this therapy does not effectively neutralize the local effects of Viperidae venoms which constitute one of the leading causes of disability or amputation of the affected limb. Thus, bioprospecting studies seeking for alternative therapies to complement antivenom should be encouraged, especially those investigating the blockage of local venomic toxicity. Plants produce a great diversity of metabolites with a wide range of pharmacological and biological properties. Therefore, the objective of this study was to assess the utilization of gallic acid, which is widely found in plants, against some toxic in vitro (coagulation, proteolytic, and hemolytic) or in vivo (edematogenic, hemorrhagic, and lethal) activities of Bothrops jararaca or B. jararacussu venom. Gallic acid was incubated with B. jararaca or B. jararacussu venom (incubation protocol), after which, in vitro or in vivo assays were performed. Additionally, a gel containing gallic acid was developed and topically applied over the skin of mice after injection of B. jararaca or B. jararacussu venom (treatment protocol), and then, a hemorrhagic assay was carried out. As a result, gallic acid inhibited the toxic activities, with variable efficacy, and the gallic acid gel neutralized B. jararaca or B. jararacussu venom-induced hemorrhagic activity. Gallic acid was devoid of in vitro toxicity as shown through a hemocompatibility test. Thus, these findings demonstrate the potential of gallic acid in the development of an alternative agent to treat victims of snake bites inflicted by Bothrops species.

Study on the synthesis and structure-activity relationship of 1,2,3-triazoles against toxic activities of Bothrops jararaca venom

Snakebite envenoming is a health concern and has been a neglected tropical disease since 2017, according to the World Health Organization. In this study, we evaluated the ability of ten 1,2,3-triazole derivatives AM001 to AM010 to inhibit pertinent in vitro (coagulant, hemolytic, and proteolytic) and in vivo (hemorrhagic, edematogenic, and lethal) activities of Bothrops jararaca venom. The derivatives were synthesized, and had their molecular structures fully characterized by CHN element analysis, Fourier-transform infrared spectroscopy and Nuclear magnetic resonance. The derivatives were incubated with the B. jararaca venom (incubation protocol) or administered before (prevention protocol) or after (treatment protocol) the injection of B. jararaca venom into the animals. Briefly, the derivatives were able to inhibit the main toxic effects triggered by B. jararaca venom, though with varying efficacies, and they were devoid of toxicity through in vivo, in silico or in vitro analyses. However, it seemed that the derivatives AM006 or AM010 inhibited more efficiently hemorrhage or lethality, respectively. The derivatives were nontoxic. Therefore, the 1,2,3-triazole derivatives may be useful as an adjuvant to more efficiently treat the local toxic effects caused by B. jararaca envenoming.

Herbal Compounds as an Antidote against Snake Bite

Snakebites have been declared a neglected health problem that must be considered a national disease of the WHO[world health organisation]. Asian countries like India have high snakebite death rates due to short antidotes and poorly equipped doctors. In today's scenario, local resources like herbs need to be used to prepare cheap antidotes and often available to victims. Snake bites should be viewed as an emergency problem and require additional national guidelines, doctor training, expertise, and human concentration for effective and timely treatment-measures to be taken to ensure the availability and mass production of antidotes. Currently available, antidotes have problems with storage, manufacture, and aspects of the results. Attention should be paid to the natural compound Gedunin with antitoxic effects. To determine Gedunin's therapeutic efficacy well-designed clinical research is required. This article emphasizes and proves the therapeutic effectiveness of the herbal plant active ingredient Gedunin against snakebites.

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.

Thrombin- and plasmin-like and platelet-aggregation-inducing activities of Plumeria alba L. latex: Action of cysteine protease

ETHNOPHARMACOLOGICAL RELEVANCE

In folk medicine, parts of Plumeria alba L. are used for the treatment of many diseases, with its latex being used for curing skin diseases and promoting wound healing.

AIM OF THE STUDY

This study aimed to study the role of P. alba L. latex in hemostasis and platelet aggregation.

MATERIALS AND METHODS

The latex of P. alba L. was processed to remove waxes and enrich protein content, and the final extract was named Plumeria alba L. natant latex (PaNL). PaNL was analyzed for protease activity against casein. The type of protease in PaNL was identified by using protease inhibitors such as E-64, phenylmethylsulfonyl fluoride, ethylenediaminetetraacetic acid, and pepstatin A. Human fibrinogen, fibrin, and collagen types I and IV were subjected to hydrolysis with different concentrations of PaNL. The thrombin-like activity of PaNL was determined by analyzing its fibrinogen-clotting and procoagulant activities. The role of PaNL in platelet aggregation was also investigated. Its hemorrhagic and edema-inducing activities were evaluated in a mouse model. Phytochemical compounds were identified by gas chromatography-mass spectroscopy.

RESULTS

The findings of casein/gelatin zymography confirmed that PaNL possesses protease activity. The results of the protease inhibition study indicated the presence of a cysteine-type protease(s) in PaNL. PaNL hydrolyzed the subunits of fibrinogen, fibrin, and collagen types I and IV. Its fibrin-degradation activity indicated that PaNL possesses plasmin-like activity. PaNL induced clotting of citrated human plasma within 3 min of incubation in the absence of CaCl_2, indicating the presence of thrombin-like activity, which was further confirmed by the results of the fibrinogen-clotting assay. PaNL induced platelet aggregation in the absence of agonists. There was no hemolytic activity. Mice injected with PaNL did not show edema/ hemorrhagic activity.

CONCLUSION

PaNL possesses procoagulant, fibrino(geno)lytic, thrombin- and plasmin-like activities and induces platelet aggregation, which could explain its usage for wound treatment in folk medicine.

Chemotaxonomy of the ethnic antidote Aristolochia indica for aristolochic acid content: Implications of anti-phospholipase activity and genotoxicity study

ETHNOPHARMACOLOGICAL RELEVANCE

Aristolochia indica L. (Aristolochiaceae) is a common medicinal plant described in many traditional medicine as well as in Ayurveda used against snakebites. Besides, the plant has also been reported traditionally against fever, rheumatic arthritis, madness, liver ailments, dyspepsia, oedema, leishmaniasis, leprosy, dysmenorrhoea, sexual diseases etc. The plant is known to contain its major bioactive constituent aristolochic acid (AA) known for its anti-snake venom, abortifacient, antimicrobial and antioxidant properties.

MATERIALS AND METHODS

This present work describes a validated, fast and reproducible high performance thin layer chromatography (HPTLC) method to estimate AA from the roots of 20 chemotypes of A. indica procured from 20 diverse geographical locations from the state of West Bengal, India. Further, an evidence-based approach was adopted to investigate the reported anti-venom activity of the aqueous extracts of the A. indica roots by assessing its phospholipase A₂ (PLA₂) inhibitory properties since PLA₂ is a major component of many snake-venoms. Finally, the cytotoxicity and genotoxicity of the aqueous root extract of the Purulia (AI 1) chemotype were assessed at various concentrations using Allium cepa root meristematic cells.

RESULTS

The highest amount of AA (7643.67 μg/g) was determined in the roots of A. indica chemotype collected from Purulia district followed by the chemotypes collected from Murshidabad, Jalpaiguri and Birbhum districts (7398.34, 7345.09 and 6809.97 μg/g respectively). This study not only determines AA in the plants to select pharmacologically elite chemotypes of A. indica, but it also identifies high AA producing A. indica for further domestication and propagation of the plants for pharmacological and industrial applications. The method was validated via analyzing inter-day and intra-day precision, repeatability, reproducibility, instrumental precision, limit of detection (LOD) and limit of quantification (LOQ) and specificity. Chemotypes with high AA content exhibited superior anti-PLA₂ activity by selectively inhibiting human-group PLA₂. Moreover, A. indica root extract significantly inhibited mitosis in Allium cepa root tips as a potent clastogen.

CONCLUSIONS

The present quick, reproducible and validated HPTLC method provides an easy tool to determine AA in natural A. indica plant populations as well as in food and dietary supplements, a potential antivenin at one hand and a possible cause of aristolochic acid nephropathy (AAN) at another. Besides, the cytotoxic and mitotoxic properties of the root extracts should be used with caution especially for oral administration.

Inhibition of key enzymes linked to snake venom induced local tissue damage by kolaviron

OBJECTIVES

Snakebite envenoming is an important public health problem that threatens the lives of healthy individuals especially in many tropical countries like Nigeria. Antivenins, the only efficient approach for snakebite envenoming, are limited in their efficacy in the neutralization of local tissue damage. Snake venom phospholipase A₂ (PLA₂), protease, hyaluronidase and l-amino acid oxidase (LAAO) are the major hydrolytic enzymes involve in local tissue damage. Therefore, this study evaluates the inhibitory effect of kolaviron (KV) against Naja n. nigricollis (NNN) snake venom hydrolytic enzymes involved in local tissue damage.

METHODS

Kolaviron was evaluated for its ability to inhibit the hydrolytic enzyme activities of NNN venom phospholipase A₂ (PLA₂), protease, hyaluronidase and l-amino acid oxidase (LAAO). Present study also deals with the neutralization of NNN venom enzyme(s) induced complications such as myotoxic, edemic, hemolytic and procoagulant effects.

RESULTS

Kolaviron inhibited the PLA₂, protease, hyaluronidase and LAAO enzyme activities of NNN venom in a dose-dependent manner. Furthermore, myotoxic, edemic, hemolytic and procoagulant effects induced by NNN venom enzyme were neutralized significantly (p<0.05) when different doses of KV were pre-incubated with venom before assays.

CONCLUSIONS

These findings clearly present kolaviron as a potent inhibitor against NNN venom hydrolytic enzymes involved in local tissue damage and may act by either forming an inhibitor-enzyme complex that restricts the substrate availability to the enzyme or direct binding to the enzyme active site that affects the enzyme activity thereby mitigating venom-induced toxicity.

Purification and characterization of non-enzymatic glycoprotein (NEGp) from flax seed buffer extract that exhibits anticoagulant and antiplatelet activity

The current study deals with the purification and characterization of non-enzymatic glycoprotein (NEGp) from flax seed buffer extract. Sephadex G-100 and DEAE-A25 column chromatography techniques were employed to isolate NEGp. NEGp showed single sharp band at 29 kDa region on 10% SDS-PAGE, and under reduced and non-reduced conditions revealed its monomeric nature. Besides, NEGp taken up the PAS stain at 29 kDa region reveals the presence of carbohydrate moiety. Purity of NEGp was adjudged by RP-HPLC, as it revealed a single sharp peak at the retention time of 3.4 min. The exact molecular mass of NEGp was found to be 26 kDa which was confirmed by MALDI-TOF. Circular di-chromism spectra of NEGp showed 12.0% α-helix, 24.3% α-helix turn and 63.7% random coils without beta pleated sheets. NEGp was found to exhibit anticoagulant activity by extending clotting time of both platelet rich plasma and platelet poor plasma from control 240 s to 1800 s and 280 s to 2100 s respectively at the concentration of 8 μg. NEGp inhibited the agonists such as ADP, epinephrine and arachidonic acid induced platelet aggregation in washed platelets. The percentage of inhibition was found to be 70%, 80% and 60% respectively. While, it did not interfere in thrombin, PAF and collagen induced platelet aggregation. NEGp did not hydrolyse RBC membrane, devoid of haemorrhagic and edema inducing properties in experimental mice.

Flaxseed Cysteine Protease Exhibits Strong Anticoagulant, Antiplatelet, and Clot-Dissolving Properties

In this study, we purified and characterized flaxseed cysteine protease (FSCP) with strong anticoagulant, antiplatelet, and clot-dissolving properties. The enzyme was purified to homogeneity by a combination of gel permeation and ion-exchange column chromatography techniques. The purity of the enzyme was evaluated by SDS-PAGE, RP-HPLC, and MALDI-TOF. FSCP was observed as a single band of approximately 160 kDa in SDS-PAGE under reducing and non-reducing conditions. The exact molecular mass of FSCP was found to be 168 kDa by MALDI-TOF spectrometry. The CD spectra of FSCP revealed the presence of 25.6% helices, 25.8% turns, and 48% random coils with no beta-sheet structures. FSCP hydrolyzed both casein and gelatin with a specific activity of 3.5 and 4.2 unit/mg min respectively. The proteolytic activity of FSCP was completely abolished by iodoacetic acid (IAA), suggesting FSCP is a cysteine protease. The pH optimum for the proteolytic activity of FSCP was pH 6.0; the temperature optimum was 30°C. FSCP exhibited strong anticoagulant effect in both platelet-rich plasma (PRP) and platelet-poor plasma (PPP) by extending the clotting time from 222 to 1100 s and from 256 to 1210 s, respectively. FSCP degraded human fibrinogen and fibrin clots. The products of fibrinogen degradation by thrombin and FSCP were different. Furthermore, FSCP inhibited aggregation of washed platelets triggered by ADP, epinephrine, thrombin, collagen, arachidonic acid, and platelet activating factor (PAF). FSCP was found to be nontoxic as it did not damage the membrane of red blood cells (RBCs) and did not induce hemorrhage and edema in experimental mice.

Gamma irradiated protease from Echis pyramidum venom: A promising immunogen to improve viper bites treatment

Echis pyramidum (Epy) is a venomous snake belongs to Viperidae family; it causes fetal coagulopathy systemic effects and death. Searching for more effective and safe antivenom is mandatory for viper bites treatment. Proteases are the most lethal components in viper venom inducing hemorrhage, edema and coagulation problems. Thus, the study aims to evaluate the potency of the prepared antisera and their neutralizing properties against the biological activities induced by whole Epy venom individually. Echis pyramidum metalloprotease enzyme (60 kDa) was purified using size-exclusion followed by DEAE-ion exchange chromatography. The purified Epy metalloprotease enzyme (SVMP) was detoxified with 1.5 kGy gamma rays from cobalt⁶⁰ gamma cell and used for immunization. 1.5 kGy irradiated Epy metalloprotease (SVMPi) showed less lethal activity (LD₅₀) compared to the corresponding native immunogen. The prepared antisera boosted against whole Epy venom (WV), 1.5 kGy irradiated whole Epy venom (WVi), SVMP and SVMPi were tested for neutralization of lethality and biological activities induced by Epy venom. The antibodies elicited against WVi and SVMPi were 30,000 and 20,000 EU, respectively. The anti-SVMPi serum showed the highest neutralization of lethality (ED₅₀) compared to the other prepared antisera. In addition, it prolonged the clotting time from 49.0 ± 2.5 to 176.2 ± 1.4 s. Furthermore, it demonstrated a highly neutralizing activity against edema induction and hemorrhage of Epy venom by 66.8% and 94.3%, respectively compared with the other prepared antisera. These findings would encourage further studies for using gamma irradiated purified fraction(s) from different snake venoms as safe antigen(s) to produce more effective antivenoms.

In vitro and in vivo inhibitory effects of Tabernaemontana alternifolia against Naja naja venom

Background

Tabernaemontana alternifolia root is traditionally used and practiced among few Indian tribes as an antidote for snakebites.

Objective

To combat and neutralize Naja naja venom using methanolic root extract of Tabernaemontana alternifolia and to explore its efficacy on venom biomarkers in search of newer herbal antidote or first-aid-point of care for therapeutics.

Materialization.

Pharmacological activities such as fibrinogenolytic, direct and indirect hemolytic activities for the neutralization of the venom were evaluated. Lethal toxicity annulation studies were performed using the murine model by pre-incubation and post-treatment protocols. Further, the neutralization of edema and myotoxicity were also evaluated.

Results

Electrophoretic analysis revealed that the complete neutralization of fibrinogen degradation was observed at 1:10 (w/w) (venom to extract). T. alternifolia exhibited an effective dose (ED₅₀) value of 87.20 µg/mL for venom-induced hemolysis. Venom at 2 µg concentration produced 11 mm of hemolytic radiance and was neutralized at 1:20 (w/w) venom to extract concentration. The survival time and the neurotoxic symptoms in mice were concluded to be delayed by both the methods of lethal toxicity inhibition using methanol extract. The edema ratio reduced the venom to extract ratio of 1:20 (w/w) from 173 ± 45% to 133.61% when subjected to 5 µg of venom concentration. The plant extract significantly neutralized the myotoxic activity.

Conclusion

T. alternifolia methanolic root extract could be a potent contributor in the effective treatment of N. naja venom-induced toxicity.

Potential use of extract of the plant Schwartiza brasiliensis (choisy) bedell ex gir.-Cañas against the toxic effects of the venom of Bothrops jararaca or B. jararacussu

Envenomation by snakes is a worldwide health public issue, and antivenoms are less efficient in neutralizing local toxic effects. Thus, more efficient therapies to treat patients deserve attention, and plants have been extensively tested. So, the aim of this work was to evaluate the effect of the aqueous fraction of the plant Schwartzia brasiliensis to inhibit some toxic activities of Bothrops jararaca or B. jararacussu venom. S. brasiliensis inhibited coagulant, hemolytic, proteolytic, hemorrhagic, edematogenic, and lethal activities of both venoms, regardless if plant was mixed together with venoms or injected after them as well as the route of administration (intravenous, oral or subcutaneous) of the plant. The S. brasiliensis extract showed no toxicity to mice or red blood cells. Thus, S. brasiliensis may be useful as an alternative treatment for snakebite envenomation and aid antivenom therapy to neutralize relevant toxic activities in patients bitten by Bothrops species.

Cellular Mechanisms for Antinociception Produced by Oxytocin and Orexins in the Rat Spinal Lamina II-Comparison with Those of Other Endogenous Pain Modulators

Much evidence indicates that hypothalamus-derived neuropeptides, oxytocin, orexins A and B, inhibit nociceptive transmission in the rat spinal dorsal horn. In order to unveil cellular mechanisms for this antinociception, the effects of the neuropeptides on synaptic transmission were examined in spinal lamina II neurons that play a crucial role in antinociception produced by various analgesics by using the whole-cell patch-clamp technique and adult rat spinal cord slices. Oxytocin had no effect on glutamatergic excitatory transmission while producing a membrane depolarization, γ-aminobutyric acid (GABA)-ergic and glycinergic spontaneous inhibitory transmission enhancement. On the other hand, orexins A and B produced a membrane depolarization and/or a presynaptic spontaneous excitatory transmission enhancement. Like oxytocin, orexin A enhanced both GABAergic and glycinergic transmission, whereas orexin B facilitated glycinergic but not GABAergic transmission. These inhibitory transmission enhancements were due to action potential production. Oxytocin, orexins A and B activities were mediated by oxytocin, orexin-1 and orexin-2 receptors, respectively. This review article will mention cellular mechanisms for antinociception produced by oxytocin, orexins A and B, and discuss similarity and difference in antinociceptive mechanisms among the hypothalamic neuropeptides and other endogenous pain modulators (opioids, nociceptin, adenosine, adenosine 5’-triphosphate (ATP), noradrenaline, serotonin, dopamine, somatostatin, cannabinoids, galanin, substance P, bradykinin, neuropeptide Y and acetylcholine) exhibiting a change in membrane potential, excitatory or inhibitory transmission in the spinal lamina II neurons.

Bungarus caeruleus venom neutralization activity of Azima tetracantha Lam. Extract

Azima tetracantha Lam. is native to Africa and India. The plant and its parts are used for treating various ailments including snake bites. The different concentrations of ethyl acetate leaf extract of A. tetracantha were used to neutralize the toxic effect of venom through dose dependent enzyme studies and in vivo studies. The extract was able to neutralize the 5’ nucleotidase, phospholipase A₂, Phosphodiesterae, phosphomonoesterase, acetylcholinesterase and hyaluronidase in a dose dependent manner with concentrations ranging from 43.98 –340.1 μg/mL of extract. The extract could retain the lysis of fibrinogen at the concentration of 1:10 (venom: extract, w/w) and also the lysis of lecithin was reduced at a concentration of 1:25 (venom: extract, w/w). The extract was able to neutralize the LD₅₀ of venom in both mice and embryo and also reduce the myotoxic and edema properties of the venom in mice models. The venom did not show any procoagulant and hemorrhagic effect. The leaf extract possess adequate compounds/phytochemicals that could neutralize the toxic properties/activity of the B. caeruleus venom.

Efficient Synthesis and in Silico Studies of the Benzimidazole Hybrid Scaffold with the Quinolinyloxadiazole Skeleton with Potential α-Glucosidase Inhibitory, Anticoagulant, and Antiplatelet Activities for Type-II Diabetes Mellitus Management and Treating Thrombotic Disorders

The current study evaluates antidiabetic, anticoagulant, and antiplatelet activity of novel benzimidazole-containing quinolinyl oxadiazoles. These derivatives are synthesized and characterized using spectroscopy (FT-IR, ¹H NMR, and mass spectroscopy) and single-crystal X-ray diffraction methods. The inhibitory effects of these compounds were evaluated by the α-glucosidase inhibitory assay and shows the activity in the range of IC₅₀ = 0.66 ± 0.05 to 3.79 ± 0.46 μg/mL. In addition, molecular docking studies revealed that benzimidazole-containing quinolinyl oxadiazoles can correctly dock into the target receptor protein of the human intestinal α-glucosidase, while their bioavailability/drug-likeness was predicted to be acceptable but requires further optimization. On the other hand, compound 8a and 8d showed anticoagulant activity as they enhanced the clotting time from control 180-410 and 180-390 s, respectively, in platelet rich plasma and 230-460 and 230-545 s in platelet poor plasma. Furthermore, only 8a showed antiplatelet activity by inhibiting epinephrine-induced platelet aggregation, and the observed aggregation inhibition was found to be 93.4%. Compounds 8a-f show nontoxic properties because of the non-hydrolyzing properties in the RBC cells. In addition, 8a and 8d show anti-edema and anti-hemorrhagic properties in the experimental mice. These findings reveal that benzimidazole-containing quinolinyl oxadiazoles act as α-glucosidase inhibitors to develop novel therapeutics for treating type-II diabetes mellitus and can act as lead molecules in drug discovery as potential antidiabetic and antithrombotic agents.

Rosemary leaves extract: Anti-snake action against Egyptian Cerastes cerastes venom

The morbidity caused by viper bites is very dangerous and the anti-venom therapy couldn't treat the local injures such as hemorrhage, edema, necrosis and inflammation of bitten tissues. Searching for safe and effective anti-venom compounds from natural sources is very important. This study was designed to explore the neutralizing ability of Rosmarinus officinalis L. leaves aqueous extract (RMAE) against Egyptian Cerastes cerastes (Cc) viper venom toxicity. The RMAE contained a considerable amount of phenolic and flavonoid contents with 3,300 and 800 mg/100 g dry weight, respectively. The RMAE showed a considerable variation of phenolic acids by using HPLC technique. Rosmarinic acid is the major component of the RMAE which recorded 400 mg/100 g dry weight and 64% of all the identified compounds. In vitro, the RMAE neutralized the enzymatic activities of proteases, l-amino acid oxidases, and phospholipases A2 of the Cc venom dose-dependently. In addition, the RMAE effectively neutralized the gelatinolytic, fibrinogenolytic, hemolytic and procoagulant activities of Cc venom. In vivo, the RMAE markedly reduced lethality, hemorrhage, edema, muscle and liver toxicities induced by Cc venom. In conclusion, the venom neutralizing property of the RMAE gives a new prospect for efficient treatment of the lethal viper bites.

Evaluation of Rhamnetin as an Inhibitor of the Pharmacological Effect of Secretory Phospholipase A2

Rhamnetin (Rhm), 3-O-methylquercetin (3MQ), and Rhamnazin (Rhz) are methylated derivatives of quercetin commonly found in fruits and vegetables that possess antioxidant and anti-inflammatory properties. Phospholipase A2 (PLA2) displays several important roles during acute inflammation; therefore, this study aimed at investigating new compounds able to inhibit this enzyme, besides evaluating creatine kinase (CK) levels and citotoxicity. Methylated quercetins were compared with quercetin (Q) and were incubated with secretory PLA2 (sPLA2) from Bothrops jararacussu to determine their inhibitory activity. Cytotoxic studies were performed by using the J774 cell lineage incubated with quercertins. In vivo tests were performed with Swiss female mice to evaluate decreasing paw edema potential and compounds’ CK levels. Structural modifications on sPLA2 were made with circular dichroism (CD). Despite Q and Rhz showing greater enzymatic inhibitory potential, high CK was observed. Rhm exhibited sPLA2 inhibitory potential, no toxicity and, remarkably, it decreased CK levels. The presence of 3OH on the C-ring of Rhm may contribute to both its anti-inflammatory and enzymatic inhibition of sPLA2, and the methylation of ring A may provide the increase in cell viability and low CK level induced by sPLA2. These results showed that Rhm can be a candidate as a natural compound for the development of new anti-inflammatory drugs.

Procoagulant serine glycoprotease from Cucumis sativus L.: action on human fibrinogen and fibrin clot

Upon examination of the fruit extract of Cucumis sativus L. for its pharmacological benefits, it was previously observed that it has potential proteolytic, fibrinogenolytic and procoagulant activities. These properties can be attributed to the presence of the protease. In this regard, the present study comprised of purification and characterization of protease. Purification of the enzyme involved ammonium sulfate precipitation followed by gel filtration and ion exchange chromatography. The purified cucumis protease (CPro) exhibits homogeneity as attested by SDS-PAGE and RP-HPLC with a retention time of 14.246 min with molecular mass ~75.3 kDa. CPro was identified as a glycoprotein and serine protease. Azocasein is the preferred substrate for CPro as it showed low K_m value of 0.3809 mg/ml. Purified CPro exhibits optimum activity at 37 °C and pH 8. CPro shows its involvement in hemostasis-the very first step in wound healing. CPro degrades the subunits of human fibrinogen in the order Aα > Bβ > γ. It also hydrolyzes the subunits of the partially cross-linked fibrin clot in the order α-polymer > γ-γ dimer > β-chain. CPro reduced the clotting time of citrated plasma, prothrombin time and activated partial thromboplastin time of plasma. CPro is neither hemorrhagic nor edema-inducing, thus considered to be a non-toxic protease. This work provides evidence for the use of cucumber extract in wound healing and authenticates its use in cosmetics.

Exploring hemostatic and thrombolytic potential of heynein - A cysteine protease from Ervatamia heyneana latex

ETHNOPHARMACOLOGICAL RELEVANCE

The latex of Ervatamia heyneana (Wall.) T. Cooke plant has been used for wound healing and various skin diseases by Indian tribes and folklore.

AIM OF THE STUDY

To validate the scientific basis of heynein - a key protease of Ervatamia heyneana, in hemostasis and wound healing process.

MATERIALS AND METHODS

The latex from E. heyneana was processed and subjected to two step purification. The purified heynein was assayed for proteolytic activity using casein as substrate and also attested by zymography. The inhibition studies confirmed the nature of heynein. Pure fibrinogen was used for fibrinogenolytic activity and citrated plasma was used for coagulant and fibrinolytic activities. The edema inducing action and hemorrhagic activity of heynein were assessed on mice model.

RESULTS

The purified heynein exhibited proteolytic activity, which was confirmed by caseinolytic assay and zymography. The inhibition studies confirmed heynein to be a cysteine protease. Heynein showed complete hydrolysis of all the three subunits of human fibrinogen (Aα, Bβ, γ). It exhibited strong pro-coagulant activity by reducing plasma clotting time from 248 to 39s at 40µg concentration. Heynein cleaved α polymer subunit in fibrin clot and did not induce edema and hemorrhage in mice models. The non-hemorrhagic nature was supported with histopathological studies of skin samples.

CONCLUSION

Heynein displays strong pro-coagulant action associated with fibrin(ogen)olytic activity. This provides basis for the observed pharmacological action of Ervatamia heyneana and thereby justifies its use in folk medicine.

Inhibition of Group IIA Secretory Phospholipase A2 and its Inflammatory Reactions in Mice by Ethanolic Extract of Andrographis paniculata, a Well-known Medicinal Food

Andrographis paniculata Nees is an important medicinal plant found in the tropical regions of the world, which has been traditionally used in Indian and Chinese medicinal systems. It is also used as medicinal food. A. paniculata is found to exhibit anti-inflammatory activities; however, its inhibitory potential on inflammatory Group IIA phospholipases A₂ (PLA₂) and its associated inflammatory reactions are not clearly understood. The aim of the present study is to evaluate the inhibitory/neutralizing potential of ethanolic extract of A. paniculata on the isolated inflammatory PLA₂ (VRV-PL-VIIIa) from Daboii rusellii pulchella (belonging to Group IIA inflammatory secretory PLA₂ [sPLA₂]) and its associated edema-induced activities in Swiss albino mice. A. paniculata extract dose dependently inhibited the Group IIA sPLA₂ enzymatic activity with an IC₅₀ value of 10.3 ± 0.5 μg/ml. Further, the extract dose dependently inhibited the edema formation, when co-injected with enzyme indicating that a strong correlation exists between lipolytic and pro-inflammatory activities of the enzyme. In conclusion, results of this study shows that the ethanolic extract of A. paniculata effectively inhibits Group IIA sPLA₂ and its associated inflammatory activities, which substantiate its anti-inflammatory properties. The results of the present study warranted further studies to develop bioactive compound (s) in ethanolic extract of A. paniculata as potent therapeutic agent (s) for inflammatory diseases.

The standard aqueous stem bark extract of Mangifera indica L. inhibits toxic PLA2 - NN-XIb-PLA2 of Indian cobra venom

The aqueous extract of Mangifera indica is known to possess diverse medicinal properties, which also includes anti-snake venom activities. However, its inhibitory potency and mechanism of action on multi-toxic snake venom phospholipases A₂s are still unknown. Therefore, the objective of this study was to evaluate the modulatory effect of standard aqueous bark extract of M. indica on NN-XIb-PLA₂ of Indian cobra venom. The in vitro sPLA₂, in situ hemolytic and in vivo edema inhibition effect were carried out as described. Also the effect of substrate and calcium concentration was carried out. M. indica extract dose dependently inhibited the GIA sPLA₂ (NN-XIb-PLA₂) activity with an IC₅₀ value of 7.6 μg/ml. M. indica extract effectively inhibited the indirect hemolytic activity up to 98% at ∼40 μg/ml concentration. Further, M. indica extract (0–50 μg/ml) inhibited the edema formed in a dose dependent manner. When examined as a function of increased substrate and calcium concentration, there was no relieve of inhibitory effect of M. indica extract on the NN-XIb-PLA₂. Further, the inhibition was irreversible as evident from binding studies. The in vitro inhibition is well correlated with in situ and in vivo edema inhibiting activities of M. indica. As the inhibition is independent of substrate and calcium and was irreversible, it can be concluded that M. indica extract mode of inhibition could be due to direct interaction of components present in the extract with the PLA₂ enzyme. The aqueous extract of M. indica effectively inhibits svPLA₂ enzymatic and its associated toxic activities, which substantiate their anti-snake venom properties. Further in-depth studies on the role and mechanism of the principal constituents present in the extract, responsible for the anti-PLA₂ activity will be interesting to develop them into potent antisnake component and also as an anti-inflammatory agent.

The anti-inflammatory activity of standard aqueous stem bark extract of Mangifera indica L. as evident in inhibition of Group IA sPLA2

ABSTRACT The standard aqueous stem bark extract is consumed as herbal drink and used in the pharmaceutical formulations to treat patients suffering from various disease conditions in Cuba. This study was carried out to evaluate the modulatory effect of standard aqueous bark extract of M. indica on Group IA sPLA2. M. indica extract, dose dependently inhibited the GIA sPLA2 (NN-XIa-PLA2) activity with an IC50 value 8.1 µg/ml. M. indica extract effectively inhibited the indirect hemolytic activity up to 98% at ~40 µg/ml concentration and at various concentrations (0-50 µg/ml), it dose dependently inhibited the edema formation. When examined as a function of increased substrate and calcium concentration, there was no relieve of inhibitory effect on the GIA sPLA2. Furthermore, the inhibition was irreversible as evidenced from binding studies. It is observed that the aqueous extract ofM. indica effectively inhibits sPLA2 and it is associated inflammatory activities, which substantiate their anti-inflammatory properties. The mode of inhibition could be due to direct interaction of components present in the extract, with sPLA2 enzyme. Further studies on understanding the principal constituents, responsible for the anti-inflammatory activity would be interesting to develop this into potent anti-inflammatory agent.

Overlapping Yet Response-Specific Transcriptome Alterations Characterize the Nature of Tobacco-Pseudomonas syringae Interactions

In this study transcriptomic alterations of bacterially induced pattern triggered immunity (PTI) were compared with other types of tobacco-Pseudomonas interactions. In addition, using pharmacological agents we blocked some signal transduction pathways (Ca(2+) influx, kinases, phospholipases, proteasomic protein degradation) to find out how they contribute to gene expression during PTI. PTI is the first defense response of plant cells to microbes, elicited by their widely conserved molecular patterns. Tobacco is an important model of Solanaceae to study resistance responses, including defense mechanisms against bacteria. In spite of these facts the transcription regulation of tobacco genes during different types of plant bacterial interactions is not well-described. In this paper we compared the tobacco transcriptomic alterations in microarray experiments induced by (i) PTI inducer Pseudomonas syringae pv. syringae type III secretion mutant (hrcC) at earlier (6 h post inoculation) and later (48 hpi) stages of defense, (ii) wild type P. syringae (6 hpi) that causes effector triggered immunity (ETI) and cell death (HR), and (iii) disease-causing P. syringae pv. tabaci (6 hpi). Among the different treatments the highest overlap was between the PTI and ETI at 6 hpi, however, there were groups of genes with specifically altered activity for either type of defenses. Instead of quantitative effects of the virulent P. tabaci on PTI-related genes it influenced transcription qualitatively and blocked the expression changes of a special set of genes including ones involved in signal transduction and transcription regulation. P. tabaci specifically activated or repressed other groups of genes seemingly not related to either PTI or ETI. Kinase and phospholipase A inhibitors had highest impacts on the PTI response and effects of these signal inhibitors on transcription greatly overlapped. Remarkable interactions of phospholipase C-related pathways with the proteasomal system were also observable. Genes specifically affected by virulent P. tabaci belonged to various previously identified signaling routes, suggesting that compatible pathogens may modulate diverse signaling pathways of PTI to overcome plant defense.

Progressive Hemorrhage and Myotoxicity Induced by Echis carinatus Venom in Murine Model: Neutralization by Inhibitor Cocktail of N,N,N',N'-Tetrakis (2-Pyridylmethyl) Ethane-1,2-Diamine and Silymarin

Viperbite is often associated with severe local toxicity, including progressive hemorrhage and myotoxicity, persistent even after the administration of anti-snake venom (ASV). In the recent past, investigations have revealed the orchestrated actions of Zn²⁺ metalloproteases (Zn²⁺MPs), phospholipase A₂s (PLA₂s) and hyaluronidases (HYs) in the onset and progression of local toxicity from the bitten site. As a consequence, venom researchers and medical practitioners are in deliberate quest of potent molecules alongside ASV to tackle the brutal local manifestations induced by aforesaid venom toxins. Based on these facts, we have demonstrated the protective efficacy of inhibitor cocktail containing equal ratios of N,N,N’,N’-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and silymarin (SLN) against progressive local toxicity induced by Echis carinatus venom (ECV). In our previous study we have shown the inhibitory potentials of TPEN towards Zn²⁺MPs of ECV (IC₅₀: 6.7 μM). In this study we have evaluated in vitro inhibitory potentials of SLN towards PLA₂s (IC_50: 12.5 μM) and HYs (IC_50: 8 μM) of ECV in addition to docking studies. Further, we have demonstrated the protection of ECV induced local toxicity with 10 mM inhibitor cocktail following 15, 30 min (for hemorrhage and myotoxicity); 60 min (for hemorrhage alone) of ECV injection in murine model. The histological examination of skin and thigh muscle sections taken out from the site of ECV injection substantiated the overall protection offered by inhibitor cocktail. In conclusion, the protective efficacy of inhibitor cocktail is of high interest and can be administered locally alongside ASV to treat severe local toxicity.

Structural Basis for the Inhibition of a Phospholipase A2-Like Toxin by Caffeic and Aristolochic Acids

One of the main challenges in toxicology today is to develop therapeutic alternatives for the treatment of snake venom injuries that are not efficiently neutralized by conventional serum therapy. Venom phospholipases A2 (PLA2s) and PLA2-like proteins play a fundamental role in skeletal muscle necrosis, which can result in permanent sequelae and disability. This leads to economic and social problems, especially in developing countries. In this work, we performed structural and functional studies with Piratoxin-I, a Lys49-PLA2 from Bothropspirajai venom, complexed with two compounds present in several plants used in folk medicine against snakebites. These ligands partially neutralized the myotoxic activity of PrTX-I towards binding on the two independent sites of interaction between Lys49-PLA2 and muscle membrane. Our results corroborate the previously proposed mechanism of action of PLA2s-like and provide insights for the design of structure-based inhibitors that could prevent the permanent injuries caused by these proteins in snakebite victims.

Biochemical and pharmacological characterization of three toxic phospholipase A2s from Daboia russelii snake venom

Three isoenzymes of phospholipase A2 (PLA2), VRV-PL-IIIc, VRV-PL-VII, and VRV-PL-IX were isolated from Daboia russelii snake venom. The venom, upon gel filtration on Sephadex G-75 column, resolved into six peaks (DRG75 I-VI). The VRV-PL-IIIc was purified by subjecting DRG75II to homogeneity by rechromatography in the presence of 8M urea on Sephadex G-75 column. The other two isoenzymes VRV-PL-VII and VRV-PL-IX were purified by subjecting DRG75III to ion exchange chromatography on CM-Sephadex C-25 column. Mol wt. for the three PLA2s, VRV-PL-IIIc, VRV-PL-VII, and VRV-PL-IX are 13.003kDa, 13.100kDa and 12.531kDa respectively. The VRV-PL-IIIc is not lethal to mice up to 14mg/kg body weight but it affects blood sinusoids and causes necrosis of the hepatocytes in liver. It causes hemorrhage in kidney and shrinkage of renal corpuscles and renal tubules. The LD50s for VRV-PL-VII and VRV-PL-IX are 7 and 7.5mg/kg body weight respectively. They induced neurotoxic symptoms similar to VRV-PL-V. All the three PLA2s are anticoagulant and induced varying degree of edema in the foot pads of mice. VRV-PL-V and VRV-PL-VII are shown to act as pre and post synaptic toxins, while VRV-PL-IX acts as presynaptic toxin. This is evident from experiments conducted on cultured hippocampal neurons by patch clamp electrophysiology.

Local and systemic toxicity of Echis carinatus venom: neutralization by Cassia auriculata L. leaf methanol extract

Viper bites cause high morbidity and mortality especially in tropical and subtropical regions, affecting a large number of the rural population in these areas. Even though anti-venoms are available, in most cases they fail to tackle viper venom-induced local manifestations that persist even after anti-venom administration. Several studies have been reported the use of plant products and approved drugs along side anti-venom therapy for efficient management of local tissue damage. In this regard, the present study focuses on the protective efficacy of Cassia auriculata L. (Leguminosae) against Echis carinatus venom (ECV) induced toxicity. C. auriculata is a traditional medicinal plant, much valued in alternative medicine for its wide usage in ayurveda, naturopathy, and herbal therapy. Further, it has been used widely by traditional healers for treatment of snake and scorpion bites in the Western Ghats of Karnataka, India. In the present study, C. auriculata leaf methanol extract (CAME) significantly inhibited enzymatic activities of ECV proteases (96 ± 1 %; P = 0.001), PLA2 (45 ± 5 %; P = 0.01) and hyaluronidases (100 %; P = 0.0003) in vitro and hemorrhage, edema and myotoxicity in vivo. Further, CAME effectively reduced the lethal potency of ECV and increased the survival time of mice by ~6 times (17 vs 3 h). These inhibitory potentials of CAME towards hydrolytic enzymes, mortal and morbid symptoms of ECV toxins clearly substantiates the use by traditional healers of C. auriculata as a folk medicinal remedy for snakebite.

In vitro screening and evaluation of antivenom phytochemicals from Azima tetracantha Lam. leaves against Bungarus caeruleus and Vipera russelli

Background

Snakebites are considered a neglected tropical disease that affects thousands of people worldwide. Although antivenom is the only treatment available, it is associated with several side effects. As an alternative, plants have been extensively studied in order to obtain an alternative treatment. In folk medicine, Azima tetracantha Lam. is usually used to treat snakebites. The present study aims to provide a scientific explanation for the use of this plant against snakebite. The extracts of shade dried leaves of A. tetracantha were tested for in vitro inhibitory activity on toxic venom enzymes like phosphomonoesterase, phosphodiesterase, acetylcholinesterase, hyaluronidase etc. from Bungarus caeruleus and Vipera russelli venoms.

Results

The ethylacetate extract rendered a significant inhibitory effect on the phosphomonoesterase, phosphodiesterase, phospholipase A₂ and acetylcholinesterase enzymes.

Conclusions

The present study suggests that ethylacetate extract of A. tetracantha leaves possesses compounds that inhibit the activity of toxic enzymes from Bungarus caeruleus and Vipera russelli venom. Further pharmacological and in vivo studies would provide evidence that this substance may lead to a potential treatment against these venoms.