Abstract
Purpose: Rhinella schneideri is a toad found in many regions of the South America. The poison of the glands has cardiotoxic effect in animals and neuromuscular effects in mice and avian preparation. The purpose of this work was to identify the toxin responsible for the neuromuscular effect in avian and mice neuromuscular preparation.Methods: The methanolic extract from R. schneideri poison was fractioned by reversed phase HPLC. The purity and molecular mass were determined by LC/MS mass spectrometry. Chick biventer cervicis and mouse phrenic-nerve diaphragm were used as neuromuscular preparations to identify the toxin.Results: The purification resulted in 32 fractions, which 4 of them were active in neuromuscular preparation. The toxin of fraction 20 were chosen for better reproducibility of the whole extract activity and its molecular mass was 730.6 Da. The toxin produced facilitation of the muscle contraction followed by a complete neuromuscular blockade in chick biventer cervicis preparation in 90 min without interfering with the exogenous response to ACh and KCl. The quantal content was increased from 128 ± 13 (control) to 216 ± 44 (after 5 min and sustained until 60 min) in the presence of the toxin.Conclusion: In conclusion, our results demonstrated that the neuromuscular action of the poison of Rhinella schneideri is a multitoxin effect. More, the present work first isolated a 730.6 Da toxin that better represent the whole poison neuromuscular effect, to which is attributed a presynaptic action in avian and mouse neuromuscular preparation.
Highlights
Rhinella schneideri is a commonly found toad in South American countries
In conclusion, our results demonstrated that the neuromuscular action of the poison of Rhinella schneideri is a multitoxin effect
The present work first isolated a 730.6 Da toxin that better represent the whole poison neuromuscular effect, to which is attributed a presynaptic action in avian and mouse neuromuscular preparation
Summary
Rhinella schneideri is a commonly found toad in South American countries. This amphibian poison is produced by a large post-orbital parotid glands and secretions help to protect against predators. This defense mode is considered as a passive mechanism of such animals since they lack spines, nails, or sharp teeth.[1] The poison is composed by biogenic amines, steroids, alkaloids, peptides and proteins.[2] The steroids are responsible for accelerating the heart rate of affected animals, and induces apoptosis and hallucinogenic effects, while peptides and proteins are believed to improve toad defense against microorganisms.[3]. Isolated compounds from R. schneideri poison have been studied in haematological models and showed ability of reducing the complement hemolytic activity of the classical/lectin pathways after preincubation with normal
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