Mesobuthus Tamulus Research Articles

N-methyl-D-aspartate receptors mediate Mesobuthus tamulus venominduced vasosensory reflex responses in anesthetized rats

Background: The autonomic changes and cardiorespiratory changes seen in vascular disorders are suggested to be mediated reflexly by the activation of perivascular nociceptors. The role of prostaglandins, vanilloid receptor 1, 5-hydroxytryptamine type 3, and kinin receptors is well established. Aims and Objectives: This study was conducted to understand the role of N-methyl-D-aspartate (NMDA) receptor in modulating vasosensory reflex responses evoked by Mesobuthus tumulus venom. Materials and Methods: Healthy male albino rats were anesthetized with an intra-peritoneal injection of urethane (1.5 g/kg). Tracheostomy was performed to keep the airway patent. Femoral artery was cannulated proximally as well as distally to record the blood pressure (BP) and to inject the chemicals, respectively. The effect of venom on BP, heart rate (HR), respiratory rate, and minute ventilation was recorded for 60 min at every 5 min and presented as mean ± standard error of mean. Results: Intra-arterial injection of venom produced immediate hyperventilatory response (increase of 41.6%), followed by hypoventilatory response (decrease of 40.1%), and finally sustained hyperventilatory response (increase of 53%) which was observed up to 60 min. The hypertensive response started at 40 s, peaking at 5 min (increase of 48%), and remained above the initial level subsequently. The bradycardiac response began around 5 min, peaking at 25 min (decrease of 50% in HR), and remained at that level up to 60 min. In 2-amino 5-phosphonovaleric acid (NMDA receptor antagonist) pre-treated group, the venom-induced cardiovascular responses (mean arterial pressure and HR) were markedly attenuated in comparisons to the venom only group but not the respiratory responses. Conclusions: The data provide evidence for the involvement of NMDA receptors in producing the venom-induced vasosensory reflex responses modulating the cardiovascular parameters in anesthetized rats.

Role of vagus in mediating the toxicity induced by Mesobuthus tamulus venom in rats

Background: Mesobuthus tumulus (red scorpion, MBT) envenomation is a serious health problem in tropical countries and is responsible for high morbidity and mortality. Aims and Objectives: Earlier reports about the role of vagus in producing MBT venom-induced toxicity are conflicting. Therefore, in this study, the role of vagus in MBT venom-induced toxicity in rats was evaluated. Materials and Methods: The rats were divided into three groups. In group I, only saline was injected. This group served as control. In group II, MBT venom was injected. In group III, MBT venom was injected in vagotomized rats. Mean arterial pressure (MAP), ECG (for heart rate [HR]), respiratory rate, pulmonary water content, and survival time were determined in all groups. Results: Exposure to MBT venom in rats produced prolonged apnea with intermittent shallow breathing and was accompanied by an instantaneous decrease, followed by an increase and then a progressive decrease in MAP and HR leading to death within 60 min. There was increased pulmonary water content (82% vs. 74% in controls). MBT venom in vagotomized rats produced immediate changes as before, but these changes recovered to reasonably good level within 30 min and the animals survived for >120 min. Pulmonary water content in vagotomized rats was similar to control group. Conclusion: The results indicate that vagus plays a vital role for the toxic effects produced by MBT venom.

Morphine blocks the Mesobuthus tamulus venom-induced augmentation of phenyldiguanide reflex and pulmonary edema in anesthetized rats.

Objective:Pulmonary edema, a manifestation of scorpion envenomation syndrome, is attributed to cardiogenic or noncardiogenic factors. Morphine is a drug used for cardiogenic pulmonary edema and its effect on Mesobuthus tamulus (MBT) venom-induced changes is not known. Therefore, we hypothesized that morphine blocks the MBT venom-induced augmentation of phenyldiguanide (PDG) reflex and pulmonary edema.Materials and Methods:Experiments were performed on anesthetized adult female rats. Trachea and jugular vein were cannulated, and the electrocardiographic potentials were recorded by connecting needle electrodes in limb lead II configuration. PDG (10 ΅g/kg, IV, bolus injection) responses were elicited by bolus injection initially, after saline/morphine (1 mg/kg) and after injecting MBT venom (100 μg/kg). The time-response area of the PDG-induced bradycardiac response after treatment was calculated as % of the initial PDG response area. At the end of experiments, lungs were excised for determination of pulmonary water content.Results:PDG produced bradycardiac response that lasted for >60 s. MBT venom augmented the PDG reflex response by 2.5 times. In morphine pretreated group, augmentation of bradycardiac response induced by MBT venom was absent. MBT venom increased the pulmonary water content, and the increase was absent in morphine pretreated animals.Conclusion:The results reveal that morphine prevents the MBT venom-induced augmentation of PDG reflex response and pulmonary edema. Thus, morphine can be useful in scorpion envenomation syndrome associated with pulmonary edema.

Scorpion bite, a sting to the heart!

Sir, We read the article “Scorpion bite, a sting to heart” by Agrawal et al.[1] with great interest. The author reported a case of 14-year-old male patient with scorpion bite on the right toe. We want to highlight certain issues regarding diagnosis and management of this patient. Cardiotoxic effects due to scorpion bite are not rare complications as demonstrated by Kumar et al. that almost more than one-third of these patients have one or more cardiovascular effects.[2] Prazosin and anti-scorpion venom (SAV) should be the primary line of treatment, as alpha receptors stimulation by the toxin results in hypertension, tachycardia, myocardial dysfunction, pulmonary edema, and cool extremities.[3] However, it has been seen that the late administration of SAV may be effective as the antivenom creates a concentration gradient between plasma and target tissue. The venom bound to antivenom gets excreted, and the toxin in the tissues moves down the concentration gradient into the blood and gets bound by the antivenom. Therefore, even if the venom is not immediately neutralized by antibodies, its removal from the tissue may cause relief in symptoms.[3] Electrocardiography (ECG) is the most important and easily available tool. No victim with systemic involvement shows normal ECG. RST segment and T waves are most frequently affected. Early myocardial infarction-like pattern, atrial arrhythmias, nonsustained ventricular tachycardia and varied conduction defect due to injury to the conducting system are seen. Conduction defect restore to normal within 1 week, T wave inversion persist for a few weeks. At times, despite good clinical status of the victim, ECG showed mark abnormalities.[4] Echocardiography is a useful tool for evaluating the various parameters of cardiac function. Echo shows poor global myocardial contractility within 12–15 h of sting, with low ejection fraction, decreased left ventricular performance, and abnormal diastolic filling for 5 days to 4 weeks. Diminished or hypokinetic left ventricular global movement with decrease systolic function was seen in the scintigraphic study. There is a good correlation between clinical improvement and return to normal left ventricular function.[5] Karnad from India studied haemodynamic pattern in eight scorpion sting cases of Mesobuthus tamulus sting. He recorded severe vasoconstriction and hypertension in mild envenoming while predominant left ventricular dysfunction with normal systemic vascular resistance causing pulmonary edema or severe hypotension in severe envenomation.[6] These patients are benefitted by the early use of inotropes and vasodilators, which reduce the afterload on the heart. These physiologic principles make dobutamine and milrinone as vasoactive drugs of choice instead of Noradrenaline as used by authors in the index case. Amiodarone a neuromodulator improves the survival by reduction of serum nor-epinephrine level in four children with scorpion sting who had severe left ventricular dysfunction with raised troponin and serum norepinephrine.[7] Early hospitalization after sting, and administration of SAV are the key factors in reducing the myocardial dysfunction, and hence related morbidity and mortality. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

B1-kinin receptors modulate Mesobuthus tamulus venom-induced vasosensory reflex responses in anesthetized rats.

Objective:Intra-arterial injection of Mesobuthus tamulus (BT) venom produces reflex vasosensory responses modulating cardiorespiratory parameters in albino rats. The present study was conducted to understand the role of kinin receptors in modulating vasosensory reflexes evoked by BT venom.Materials and Methods:In urethane-anesthetized rats, tracheostomy was performed to keep the airway patent. The femoral artery was cannulated proximally, as well as distally, to record the blood pressure (BP) and to inject the chemicals, respectively. Electrocardiographic and respiratory excursions were recorded to compute the heart rate (HR) and respiratory rate (RR). A group of animals was pretreated with saline/kinin receptor antagonists intra-arterially (B1/B2 receptor antagonists) before the injection of venom.Results:After intra-arterial injection of BT venom (1 mg/kg), there was an immediate increase in RR, which reached to 40% within 30 s, followed by a decrease of 40%. Further, there was sustained increase in RR (50%) up to 60 min. The BP started to increase at 40 s, peaking at 5 min (50%), and remained above the initial level up to 60 min. The bradycardiac response started after 5 min which peaked (50% of initial) at 25 min and remained at that level up to 60 min. In B1 receptor antagonist (des-Arg) pretreated animals, venom-induced cardiovascular responses were attenuated (by 20–25% in mean arterial pressure and HR) significantly but not in B2 receptor antagonist (Hoe-140) pretreated animals. Either of the antagonists failed to alter the RR responses.Conclusions:BT venom-induced vasosensory reflex responses modulating cardiovascular parameters are mediated via B1-kinin receptors in anesthetized rats.

Intra-aortic balloon pump (IABP) rescue therapy for refractory cardiogenic shock due to scorpion sting envenomation

Background: Cardiomyopathy, cardiogenic shock or acute pulmonary oedema are well recognised complications of scorpion sting envenomation occurring in about 1–3% of patients. Current treatment recommendations include afterload reduction using prazosin and improving cardiac contractility with inotropes like dobutamine. We report the use of intra-aortic balloon pump (IABP) as rescue therapy in a patient with refractory cardiogenic shock due to Mesobuthus tamulus (Indian red scorpion) envenomation. Case: A 32-year-old woman was referred 24 h after a scorpion sting. At presentation she was ventilated and in circulatory shock (systolic blood pressure <50 mmHg). After admission, the patient had four cardiac arrests (three episodes of pulseless ventricular tachycardia/ventricular fibrillation and one episode of asystole) over the next few hours. Following resuscitation, despite a combination of dobutamine, noradrenaline, and adrenaline, blood pressure did not improve significantly. In view of persistent tachycardia (heart rate 160/min), catecholamine storm was suspected and prazosin was added. However, shock was refractory. Hence, IABP was considered as rescue therapy. Following initiation of IABP, there was improvement in cardiac function (improved ejection fraction) which translated to weaning of inotropes over 48 h and improved organ function (renal, respiratory) in the next 2–3 d. However, following extubation, on Day 8, she was noted to have features of hypoxic brain injury. This improved gradually. At discharge (Day 30) she was independent for activities of daily living and was able to mobilise without support. Conclusion: IABP could be generally considered as a rescue therapy in refractory cardiogenic shock in envenomations.

Indian scorpions collected in Karnataka: maintenance in captivity, venom extraction and toxicity studies.

BackgroundMaintenance of scorpions under laboratory conditions is ideal for long-term venom collection to explore the therapeutic applications of scorpion venom. Collection of venom by electrical stimulation requires a reliable stimulator and effective restrainer. Thus, the present study was conducted to develop a convenient method to maintain scorpions and to extract their venom for toxicity studies via a modified restrainer and stimulator.MethodsFour different scorpion species were collected, among which three species were maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from Hottentotta rugiscutis by electrical stimulation at 8 V for 18 months and LD50 was estimated by the graphic method of Miller and Tainter.ResultsA total of 373 scorpions including Hottentotta rugiscutis, Hottentotta tamulus, Lychas tricarinatus and Heterometrus swammerdami were collected, identified and maintained successfully, achieving a 97 % survival rate. Hottentotta rugiscutis yielded 6.0 mL of venom by electrical stimulation. The LD50 of H. rugiscutis venom was estimated to be 3.02 mg/kg of body weight in female Swiss albino mice.ConclusionsScorpions were successfully maintained for 18 months. Herein we have also documented a simple, cost-effective method of venom extraction by electrical stimulation using a modified restrainer. Furthermore, Hottentotta rugiscutis was reported for the first time in Karnataka.

Vagal efferent stimulation protects against Mesobuthus tamulus venom-induced acute respiratory distress syndrome in rats

Mesobuthus tamulus (MBT) venom and oleic acid (OA) have been shown to produce acute respiratory distress syndrome (ARDS) involving different mechanisms. The role of vagally mediated anti-inflammatory pathway in ARDS is poorly understood. Therefore, the effects of vagal efferent stimulation on these two models of ARDS were examined. Experiments were performed on anesthetized adult rats. Parameters like ventilatory changes (respiratory frequency and minute ventilation), hypoxemic status (PaO2/FiO2 ratio; P/F ratio), survival time, pulmonary water content and histopathological evidences of lung injury were determined to assess the severity of ARDS. In addition, heart rate (HR) and mean arterial pressure (MAP) were monitored. Injection of OA/MBT venom produced respiratory alterations, hypoxemia, pulmonary edema and histopathological changes demonstrating the development of ARDS. In both the groups, animals died around 60 min. Tachypnea and hyperventilation were seen after OA while bradypnea and hypoventilation were seen after MBT venom. Pulmonary edema was absent in vagotomised animals in MBT venom group but not in OA group. Further, electrical stimulation of the cut peripheral ends of vagii prolonged the survival time and attenuated all the parameters of MBT venom-induced ARDS significantly. In case of OA, there was improvement in histopathological changes but the survival time of animals was not prolonged. Stimulation of α7-nicotinic receptors (by pretreatment with GTS-21) exacerbated OA as well as MBT venom-induced ARDS. The present results indicate that vagal efferent stimulation protects against MBT venom-induced ARDS.

Oxidative stress-induced methemoglobinemia is the silent killer during snakebite: a novel and strategic neutralization by melatonin.

Oxidative stress-induced methemoglobinemia remained an untouched area in venom pharmacology till date. This study for the first time explored the potential of animal venoms to oxidize hemoglobin to methemoglobin. In in vitro whole-blood assay, methemoglobin forming ability of venoms varied as Naja naja > Ophiophagus hannah > Echis carinatus > Daboia russellii > Apis mellifera > Mesobuthus tamulus > Hippasa partita. Being highly potential, N. naja venom was further studied to observe methemoglobin formation in RBCs and in combinations with PMNs and PBMCs, where maximum effect was observed in RBCs + PMNs combination. Naja naja venom/externally added methemoglobin-induced methemoglobin formation was in parallel with ROS generation in whole blood/RBCs/RBCs + PMNs/RBCs + PBMCs. In in vivo studies, the lethal dose (1 mg/kg body weight, i.p.) of N. naja venom readily induced methemoglobin formation, ROS generation, expression of inflammatory markers, and hypoxia-inducible factor-3α. Although the mice administered with three effective doses of antivenom recorded zero mortality; the methemoglobin and ROS levels remained high. However, one effective dose of antivenom when administered along with melatonin (1:50; venom/melatonin, w/w), not only offered 100% survival of experimental mice, but also significantly reduced methemoglobin level, and oxidative stress markers including hypoxia-inducible factor-3α. This study provides strong drive that, complementing melatonin would not only reduce the antivenom load, but for sure greatly increase the success rate of antivenom therapy and drastically minimize the global incidence of snakebite deaths. However, further detailed investigations are needed before translating the combined therapy towards the bed side.

Predictors of myocardial dysfunction in children with indian red scorpion (Mesobuthus tamulus) sting envenomation

To identify predictive risk factors for myocardial dysfunction in children with scorpion sting envenomation and to evaluate the effects of Scorpion antivenom and prazosin combination therapy on occurrence of myocardial dysfunction. Observational. Tertiary care hospital in Southern India. 85 children aged <13 years with scorpion sting envenomation. Frequency of myocardial dysfunction; predictors of myocardial dysfunction. 24 children (28.2%) developed myocardial dysfunction. Hypotension at admission (P=0.003) and increased time (>4h) between sting and administration of appropriate therapy (P=0.001) were independent predictors of myocardial dysfunction on logistic regression. Scorpion antivenom plus prazosin combination therapy led to an increase in cumulative proportion of children without myocardial dysfunction. Early (<4 hours) administration of Scorpion antivenom along with prazosin increases the cumulative percentage of children not developing myocardial dysfunction.

Clinical profile of scorpion sting from north Uttar Pradesh, India

Background: Scorpion sting envenomation is an acute life-threatening, time-limited medical emergency, commonly seen in villagers. Among the 86 species of scorpions identified in India, Mesobuthus tamulus and Palamnaeus are of medical importance. Morbidity and mortality due to scorpion sting are related to acute pulmonary edema, cardiogenic shock, and multiorgan failure. Objective: To evaluate the pattern of presentation and the primary care to be taken to avoid mortality. Materials and Methods: A total of 210 patients of consecutive scorpion sting were prospectively studied. The data included demographics, the time of presentation to the hospital (Jeevan Jyoti Hospital, Allahabad, Uttar Pradesh, India), and clinical features. Results: Local pain, sweating, and tachycardia were the common clinical presentations. The red scorpion sting was seen in 60% cases, and the site of sting was found to be the foot region in 61% cases. Conclusion: Scorpion sting is an acute life-threatening emergency, and an early presentation to the hospital and an early as possibly. We advocate that a prevention method in the form of a health education program carried out by health-care workers.

Severe Scorpion Envenoming Results in Acute Myocardial Infarction

Mesobuhus Tamulus (An Indian red scorpion) flourished allover coastal region of India. Its venom is neuronal sodium channels activators. Envenoming by red scorpion evokes autonomic storm. Severe cardiovascular manifestations occurred as a result of high circulating catecholamines. We report a case of severe scorpion envenoming who suffered of autonomic storm and subsequent acute inferior wall myocardial infarction, lethal ventricular arrhythmias. He recovered with intravenous scorpion antivenin, oral prazosin and intravenous bolus of 30 mg tenectiplase. Key words: Scorpion, scorpion antivenom, prazosin, myocardial infarction.

Clinico-epidemiology of stings and envenoming of Hottentotta tamulus (Scorpiones: Buthidae), the Indian red scorpion from Jaffna Peninsula in northern Sri Lanka

In recent years, stings of a lethal scorpion species were recorded from Jaffna Peninsula in the northern dry zone of Sri Lanka. This species was identified as Hottentotta tamulus (Scorpiones: Buthidae) which is the Indian red scorpion commonly found in Maharashtra, India. The Teaching Hospital, Jaffna recorded 84 H. tamulus stings over a year in 2012 and of them, 23 cases provided offending scorpions (proven cases). Three localities in Jaffna were recorded as hotspots of scorpion stings namely Palali, Achchuvali and Karainagar. Of the proven cases, 13 (57%) and 10 (43%) were males and females respectively and had a mean age of 30 years (SD ± 20 years). Among them, 5 (22%) were children below 12 years. In 13 (57%) patients stings occurred inside their houses including two children (40%). Six (26%) stings occurred at night when the victims were in sleep. Median time taken to arrive at the hospital from the time of stinging was 58 min (range 8–550 min). Signs of over activation of autonomic nervous system predominated the clinical picture-tachycardia in 14 (61%), high blood pressure in 11 (48%), excessive sweating in 9 (39%), excessive salivation in 5 (22%), hypotension in 4 (17%) and piloerection in 3 (13%). Children showed higher predilection to develop tachycardia – 4 (80%) and excessive salivation – 3 (60%). Priapism was not observed and 17 (74%) patients have developed intense pain at the site of sting. The commonest ECG change was tachycardia (73%) and occasional T wave inversion. Prazosin as a treatment was given to 22 (96%) patients. All patients made recovery and 13 (57%) patients left the hospital within two days. In future, there is a potential risk of spreading this species to elsewhere in the country and may disturb the ecological balance.

Efficacy of scorpion antivenom plus prazosin versus prazosin alone for Mesobuthus tamulus scorpion sting envenomation in children: a randomised controlled trial

ObjectiveTo assess the efficacy of combined use of scorpion antivenom (SAV) with prazosin, compared with prazosin alone in children with Mesobuthus tamulus scorpion envenomation.Study designRandomised controlled trial.SettingA tertiary care hospital...

Anti-arthritic Effect of Indian Red Scorpion (Mesobuthustamulus) Venom in Freund’s Complete Adjuvant and Collagen Type II Induced Arthritis

Aim of the present study was to observe the effect of Indian red scorpion venom (SV) in the treatment of Freund’s complete adjuvant (FCA) induced arthritis and collagen type II (CII) induced arthritis models in rats. The immunosuppressant action of SV was confirmed by hemagglutination antibody titre. The further results also suggest that SV produce analgesia in both developing and developed phases of arthritis when evaluated on various pain perception models. SV significantly reduced the paw edema volume and ankle joint diameter in arthritic paw of rats. The altered hematological and biochemical parameters were brought to normal by SV in arthritic conditions when tested on experimental animals. Further anti-arthritic activity of SV was confirmed from the histopathological and radiological findings.

Scorpion Stings: Focus on Cerebrovascular Complications of Envenoming

Dear editor, Scorpion stings kills thousands of people every year (1). Clinical picture of envenoming is dominated by local pain, weakness, arterial hypertension, cardiac arrhythmias, myocarditis, or pulmonary oedema. These manifestations occur as the result of massive release of catecholamines into the bloodstream or due to direct toxicity of the venom (2). Cerebrovascular complications occur in up to 8% of severely envenomed scorpion sting victims, particularly after the sting of Mesobuthus thalamus (Indian red scorpion). Intracranial haemorrhages occur in the setting of acute increases in blood pressure related to sympathetic overstimulation, and cerebral infarctions are related to cerebral hypoperfusion, consumption coagulopathy, vasculitis, intracranial vessels spasm, or cardiogenic brain embolism (3,4). A PubMed search revealed 23 well-documented cases of stroke following scorpion stings (mean age 25 years; 71% men). Fifteen patients (65%) had ischaemic and eight had haemorrhagic strokes. Infarctions were located in the middle cerebral artery territory (six patients), watershed areas between major cerebral arteries (three patients), the cerebellum (two patients), multiple arterial territories (two patients), and the posterior cerebral artery territory and the pons (one patient each). Pathogenetic mechanisms responsible for the infarction were suspected in 13 patients, six of whom had cerebral hypoperfusion (related to systemic hypotension), four had disseminated intravascular coagulation, two had vasculitis, and one had spasm of intracranial arteries. Haemorrhagic strokes were located in the basal ganglia in four cases, the subcortical white matter in two, and the ventricular system in one. The remaining patient had multiple intracranial haemorrhages. In seven cases, the cause of the haemorrhage was an increase in arterial blood pressure occurring as part of the ‘autonomic storm’ observed in scorpion sting victims. Prompt management of these patients reduces stroke morbidity and mortality. Prazosin reverses the overstimulation of peripheral a1-adrenergic receptors and reduces the risk of cardiac and pulmonary complications. While the use of antivenom has been questioned due to allergic reactions, combination therapy with antivenom plus prazosin was more effective than prazosin alone for enhancing recovery in a recent trial (5).

Computational analysis of bioactive phytochemicals as potential inhibitors for calcium activated potassium channel blocker, tamulotoxin from Mesobuthus tamulus

Several research works are being carried out on natural medicines because they are cost effective and play a vital role in providing a permanent remedy. Phytochemicals are pharmacologically important source of plant products which targets many diseases especially finding antidote for envenomation. Accidental toxin bite becomes highly lethal due to lack of proper treatment. The red Indian scorpion, Mesobuthus tamulus produces a highly toxic protein called tamulotoxin (TmTx). TmTx blocks the Ca2+ activated K+ ion channels, which is responsible for cellular proliferation and migration. Several antidotes were used for neutralizing the action of scorpion bites because most of the synthetic drugs produce undesirable side effects. In this work, we have found some of the potential lead molecules (chemical compounds and their analogs) obtained from plant source and a series of bioinformatics based studies including computational analogs search, virtual screening, pharmacokinetic profiling and molecular interaction were executed. From this study, we suggest that some of the potential ligands having a therapeutic effect against TmTx protein. This work will help researchers to enhance their analysis toward designing a protocol for antidote based therapy against TmTx protein.

First report on Hottentotta tamulus (Scorpiones: Buthidae) from Sri Lanka, and its medical importance

A scorpion species proved to be lethal to humans was recently recorded from Jaffna Peninsula (9°40'0''N 80°0'0''E, mean annual temperature 26.2°C), in the northern dry zone of Sri Lanka. This species is morphologically different from all other known scorpions in Sri Lanka. The species was identified as Hottentotta tamulus (Scorpiones: Buthidae), which is commonly found in Maharashtra, India, the closest mainland to Sri Lanka. Small children and housewives were most of the victims. Soon after sting, the patient develops intense pain at the site of sting followed by numbed sensation. Dominant clinical effects include excessive sweating, agitation and palpitation. Blood pressure of the victim goes up, and if not promptly treated leads to acute heart failure. There is a high risk of spreading of this species to the rest of the country due to transport of goods and sand from the area.

Anti-scorpion venom activity of Andrographis paniculata: A combined and comparative study with anti-scorpion serum in mice

Objectives:The objective of this study is to evaluate the anti-scorpion venom (ASV) property of Andrographis paniculata in comparison with anti-redscorpion venom serum and this study aimed to determine its combined effect with anti-redscorpion venom serum.Materials and Methods:Ethanolic extract of the plant AP was obtained using soxhlet apparatus. Swiss albino mice weighing 20-30g were used. Lyophilized venom sample of Mesobuthus tamulus and Lyophilized monovalent enzyme refined immunoglobulin anti-scorpion venom serum (ASV) was used. Using lethal dose of scorpion venom (25.12μg/g), the venom neutralizing ability of plant extract (1 g/kg) and ASV individually as well as in combination was studied using in vivo and in vitro methods. Mean survival time, protection fold and percentage survival of animals over the period of 24 h were the parameters used.Statistical Analysis:Results were analyzed using Student's t-test.Results:Ethanolic extract of AP (1 g/kg) showed some protective effect against scorpion venom. ASV was found more effective than plant extract. But, when plant extract and ASV were used in combination, potency of ASV was found to be increased both in vivo and in vitro.Conclusions:Present study demonstrates that, both plant extract and ASV have their own scorpion venom neutralising ability in vivo and in vitro, but their combination is most effective in venom neutralizing ability.

Heteromtoxin (HmTx), a novel heterodimeric phospholipase A2 from Heterometrus laoticus scorpion venom

Heteromtoxin (HmTx) is a group III phospholipase A2 produced in Heterometrus laoticus, in Thailand. In this study, HmTx was purified from venom by separation chromatography, and the PLA2 activity of the fractions was determined by lecithin agar assay. The enzyme is an acidic protein with a pI of 5.6 and an apparent molecular weight of 14018.4 Da. The nucleotide sequence of HmTx contains 649 bp, and the mature protein is predicted to have 131 amino acid residues—104 of which make up the large subunit, and 27 of which make up the small subunit. The subunit structure of HmTx is highly similar to that of the other toxin, Pandinus imperator imperatoxin I (IpTxi) and to Mesobuthus tamulus phospholipase A2 (MtPLA2). The 3D-structure of HmTx consists of three conserved alpha-helices: h1 (Lys24–His34), h2 (Cys59–Asp71), and h3 (Ala80–Phe89). The beta-sheet consisted of a single stranded anti-parallel beta-sheet (b1.1 at Glu43–Lys45 and b1.2 at Lys48–Asn50) that was highly similar to the conserved sequences (–CGXG–, –CCXXHDXC– and CXCEXXXXXC–) of Apis mellifera (bee) phospholipases.