Biochemical and Proteomic Characterization, and Pharmacological Insights of Indian Red Scorpion Venom Toxins.

The Indian red scorpion (Mesobuthus tamulus) is one of the world's deadliest scorpions, with stings representing a life-threatening medical emergency. This species is distributed throughout the Indian sub-continent, including eastern Pakistan, eastern Nepal, and Sri Lanka. In India, Indian red scorpions are broadly distributed in western Maharashtra, Saurashtra, Kerala, Andhra Pradesh, Tamil Nadu, and Karnataka; however, fatal envenomations have been recorded primarily in the Konkan region of Maharashtra. The Indian red scorpion venom proteome comprises 110 proteins belonging to 13 venom protein families. The significant pharmacological activity is predominantly caused by the low molecular mass non-enzymatic Na+ and K+ ion channel toxins. Other minor toxins comprise 15.6% of the total venom proteome. Indian red scorpion stings induce the release of catecholamine, which leads to pathophysiological abnormalities in the victim. A strong correlation has been observed between venom proteome composition and local (swelling, redness, heat, and regional lymph node involvement) and systemic (tachycardia, mydriasis, hyperglycemia, hypertension, toxic myocarditis, cardiac failure, and pulmonary edema) manifestations. Immediate administration of antivenom is the preferred treatment for Indian red scorpion stings. However, scorpion-specific antivenoms have exhibited poor immunorecognition and neutralization of the low molecular mass toxins. The proteomic analysis also suggests that Indian red scorpion venom is a rich source of pharmacologically active molecules that may be envisaged as drug prototypes. The following review summarizes the progress made towards understanding the venom proteome of the Indian red scorpion and addresses the current understanding of the pathophysiology associated with its sting.

Correlation of Venom Toxinome Composition of Indian Red Scorpion (Mesobuthus tamulus) with Clinical Manifestations of Scorpion Stings: Failure of Commercial Antivenom to Immune-Recognize the Abundance of Low Molecular Mass Toxins of This Venom.

The Indian red scorpion (Mesobuthus tamulus), with its life-threatening sting, is the world's most dangerous species of scorpion. The toxinome composition of M. tamulus venom was determined by tandem mass spectrometry (MS) analysis of venom protein bands separated by SDS-PAGE. A total of 110 venom toxins were identified from searching the MS data against the Buthidae family (taxid: 6855) of toxin entries in nonredundant protein databases. The Na+ and K+ ion channel toxins taken together are the most abundant toxins (76.7%) giving rise to the neurotoxic nature of this venom. The other minor toxin classes in the M. tamulus venom proteome are serine protease-like protein (2.9%), serine protease inhibitor (2.2%), antimicrobial peptide (2.3%), hyaluronidase (2.2%), makatoxin (2.1%), lipolysis potentiating peptides (1.2%), neurotoxin affecting Cl- channel (1%), parabutoporin (0.6%), Ca2+ channel toxins (0.8%), bradykinin potentiating peptides (0.2%), HMG CoA reductase inhibitor (0.1%), and other toxins with unknown pharmacological activity (7.7%). Several of these toxins have been shown to be promising drug candidates. M. tamulus venom does not show enzymatic activity (phospholipase A2, l-amino acid oxidase, adenosine tri-, di-, and monophosphatase, hyaluronidase, metalloproteinase, and fibrinogenolytic), in vitro hemolytic activity, interference with blood coagulation, or platelet modulation properties. The clinical manifestations post M. tamulus sting have been described in the literature and are well correlated with its venom proteome composition. An abundance of low molecular mass toxins (3-15 kDa) are responsible for exerting the major pharmacological effects of M. tamulus venom, though they are poorly immune-recognized by commercial scorpion antivenom. This is a major concern for the development of effective antivenom therapy against scorpion stings.

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.

The action of red scorpion (Mesobuthus tamulus coconsis, pocock) venom and its isolated protein fractions on blood sodium levels

Red scorpion (Mesobuthus tamulus or Buthus tamulus) venom samples were collected at different regions of India: western (Chiplun and Ahmednagar from Maharashtra State) and southern (Ratnagiri and Chennai from Tamil Nadu State). The action of whole venoms on the blood sodium levels of mice was assessed using flame photometry. Seven peptides were common to all venom samples. They were separated using the native polyacrylamide gel electrophoresis (PAGE) technique and their activities were also studied using flame photometry. There was a decrease in the concentration of sodium ions in the serum, which suggested the blockage of such ions by scorpion venom toxins. Among the 10 protein bands isolated, the band at 79.6 kDa presented maximum activity in decreasing serum sodium ions concentration. Whole venom from Chiplun region also showed maximum activity. The western blotting technique demonstrated that the anti-scorpion venom sera produced by Haffkine Biopharmaceuticals Corporation Ltd., India, neutralized all four venom samples.(AU)

Intraspecific variation in protein pattern of red scorpion (Mesobuthus tamulus, coconsis, pocock) venoms from Western and Southern India

Red scorpions Mesobuthus tamulus (Coconsis, Pocock) were obtained from different regions of West and South India (Ratnagiri, Chiplun and Ahmednagar from Maharashtra and Chennai from Tamil Nadu, respectively). Their venoms composition was analyzed using gel electrophoresis (SDS-PAGE). All venom samples shared six bands of 170, 80, 60, 57, 43, and 38 kDa molecular weights. Bands of 115 kDa and 51.5 kDa were characteristic of venoms obtained from red scorpions of Chiplun region, and the 26kDa band was absent in scorpion venom from Tamil Nadu. The separated protein band patterns suggest that the venoms from Ratnagiri, Ahmednagar and Tamil Nadu had high similarities in their biochemical composition but differed from that of Chiplun region. These data were also supported by the Jaccard (J) index. The J value was 0.33 for venom obtained from Ratnagiri-Ahmednagar, 0.31 for venom from Ratnagiri-Tamil Nadu, and 0.3 for venom from Ratnagiri-Chiplun region. This suggests the existence of genetic variation among the different strains of red scorpion in western and southern India. The antiserum produced by Haffkine Biopharmaceuticals Corporation Ltd. completely neutralized proteins of venoms from all the regions studied.(AU)