Determination of median effective dose (ED50) of scorpion antivenom against scorpion envenomation using a newly developed formula

Morphometric Indices and Venom Protein Profile in Different Populations of Androctonus crassicauda

Background

Androctonus crassicauda is the most medically relevant animal and understanding its morphological characteristics is essential in the production of antiscorpion sera.

Methods

Adults of A. crassicauda were collected from different areas of Zanjan Province and the morphometric parameters and the cuticular fluorescence patterns of samples were studied. The crude venom of samples was extracted by electric stimulation, and their biochemical properties were analyzed by the SDS-PAGE method.

Results

Values of the morphometric parameters depended on sex and altitude of the area. Except for values of the pectinal organ, these parameters in females were higher than in males. No significant difference was in the number, shape, and intensity of cuticular fluorescence patterns. The body length of males in high and lowlands was 72.53±1.53 and 77.33±2.70mm, respectively. Females' body lengths in that area were 81.66±2.19 and 86.55±2.33mm, respectively. Analysis of toxin proteins showed two isotypes that the 12, 13, 15, 16, 18, and 19kDa proteins were in all areas. However, the 41 and 74kDa proteins, and 46 and 63kDa proteins were detected in low and highlands, respectively.

Conclusion

Black fat-tailed scorpion has a considerable dominancy and developing preventive programs and providing treatment facilities in studied areas are necessary. Values of the morphological parameters and venom electrophoresis patterns depended on the geographical location. Therefore, pool crude toxin is suggested for the production of effective antivenoms. Moreover, additional field complementary works in the geographic information system based niche modeling and mass fingerprinting of scorpion venoms are suggested for screening effective isotypes.

Toxicity and protein composition of venoms of Hottentotta saulcyi, Hottentotta schach and Androctonus crassicauda, three scorpion species collected in Iran

BACKGROUND

Scorpion stings comprise a serious problem throughout the globe, especially in regions where they are more frequent. Despite a recent upsurge of interest in scorpion venoms by various research groups, there remain many challenges.

OBJECTIVE

Therefore, in this study, we aimed to study the toxicity and protein composition of venoms of Hottentotta saulcyi, Hottentotta schach and Androctonus crassicauda, three scorpion species collected in Iran.

MATERIALS AND METHODS

Scorpion species were collected from Esfahan farm scorpion company and maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from A. crassicauda, H. schach and H. saulcyi by electrical stimulation of 8 and 10 V. The toxicity of each venom was established by using four groups of male Swiss albino mice aged 2 months (weighting 18-20 g) for testing each dose of venom. One group was used as a control. Venom was injected into mice by subcutaneous route. Then, animals were monitored for 24 h and LD₅₀ was estimated by the graphic method of Miller and Tainter. Thus, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was used to determine amino acids in the venom, and protein concentrations were determined by the Biuret method.

RESULTS

LD₅₀ of scorpion venoms by subcutaneous route was found to be 1.70 mg/kg b.w (A. crassicauda), 1.47 mg/kg b.w (H. saulcyi) and 0.85 mg/kg b.w (H. schach). A. crassicauda, H. saulcyi and H. schach contain 26, 30, and 31 amino acids, respectively. A. crassicauda contains low concentrations of alpha-aminoadipic acid, beta-aminoisobutyric acid, beta-alanine and citrulline. H. saulcyi contains a concentration of hydroxylysine, whereas H. schach has no such concentration. A. crassicauda also had the highest levels of tyrosine and threonine. Only A. crassicauda venom contains a low proportion of proteins (14.80%) compared with those of H. schach (16.26%) and H. saulcyi (16.20%). Albumin content in the venoms was 11.7% (H. saulcyi), 5.4% (H. schach) and 4.4% (A. crassicauda).

CONCLUSION

Scorpions venoms have a variable toxicity and an interesting composition in amino acids and proteins. Work on the development of anti-venom is fundamental.

Comparison of venom from wild and long-term captive Gloydius caucasicus and the neutralization capacity of antivenom produced in rabbits immunized with captive venom

Gloydius caucasicus (NIKOLSKY, 1916) is a member of the Viperidae family in Iran. Comprehensive understanding of the toxigenic characteristics of snake venom is important for clinical monitoring of snakebite patients and effective therapy. We compared the toxic activities of venoms and the neutralization capacity of antivenoms produced with venoms from wild adult (WA) with long-term captive adult (LCA) of G. caucasicus in order to obtain more effective antivenom from LCA in therapy, and subsequently protect G. caucasicus from overharvesting for its venom, which poses a real threat of extinction for the species. Our results showed that LD50 of WA and LCA were 16.8 μg/dose and 17.7 μg/dose, respectively. Lower hemorrhagic and necrotic (p ≥ 0.05), and higher coagulative and edematogenic activities (p ≤ 0.05) were observed in WA compared with LCA venom. Also, captive-born neonates exhibited weaker toxic activities compared with captive adult snakes, which could be an age-related difference. Study data illustrated that effective capacity of LCA antivenom to neutralize the toxic activities of WA viper venom. According to the results, about 0.4-4 μl of LCA antivenom is required to neutralize the toxic activities of 1 μg of WA venom, indicating its efficacy in treatment of snakebites in humans. On this basis, it is recommended that capture of wild snakes for their venom be discontinued to reduce their future extinction risk.

Comparative therapeutic index, lethal time and safety margin of various toxicants and snake antivenoms using newly derived and old formulas

OBJECTIVE

The assessment of clinical efficacy and toxicity is very important in pharmacology and toxicology. The effects of psychostimulants (e.g. amphetamine), psychotomimetics (e.g. Cannabis sativus) and snake antivenoms are sometimes unpredictable even at lower doses, leading to serious intoxication and fatal consequences. Hence, there is need to re-assess some formulas for calculation of therapeutic index, lethal time and safety margin with a view to identifying therapeutic agents with remarkable toxicity potentials.

RESULTS

The therapeutic index formula [Formula: see text] was derived from T1 = LD50/ED50 and ED50 = [Formula: see text]. Findings have shown that, therapeutic index is a function of death reversal (s), safety factor (10-4) and weight of animal (Wa). However, the new safety margin formula [Formula: see text] derived from LT50 = [Formula: see text] and MS = [Formula: see text] shows that safety margin is a function of cube root of ratio between LT50 and LD50 and ED100th. Concentration (k) of toxicant at the receptor [Formula: see text] derived from D1 × Tn = K and LD1 = [Formula: see text] shows that therapeutic index, lethal time and safety margin is a function of drug or toxicant concentration at the receptor, the drug-receptor interaction and dose of toxicant or drug administered at a particular time.