Bird Families

Batrachotoxin - poison of poison dart frogs

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What is batrachotoxin

It is a natural organic compound from the group of steroidal alkaloids. Batrachotoxin is a non-protein poison, one of the most potent zoological toxins. The substance is a derivative of the steroid pregnin. It is an ether of crystalline structure, insoluble in water.

Chemical formula of batrachotoxin - C31H42N2O6... Its molecular weight is 538.68 g / mol, density is 1.304 g / cm 3. In alkaline media, the compound decomposes, in alcohols it is capable of dissolving.

The study of batrachotoxin began in the sixties of the last century. A scientific expedition collected about a thousand tree frogs in Colombia. The extraction of the poisonous secretion was carried out immediately after the capture of animals - this was done for insurance, since in the event of the death of amphibians during transportation, the possibility of obtaining poison would be lost. In 1962-1963, American scientists Daley and Whitkop isolated pure poison from the secretion of the dermal glands of poison dart frogs. It turned out to be combined and consisted of four toxins:

  • pure batrachotoxin,
  • isobatrachotoxin,
  • pseudobatrachotoxin,
  • batrachotoxin A.

Only after a comprehensive study of the structure and properties of the components of the poison, in the late nineties of the XX century, the synthesis of this organic compound was carried out.

The origin of the poison

Translated from Greek, "batrachotoxin" means frog toxin. These representatives of amphibians, living in the tropical forests of Central and South America, where the humidity reaches 80%, are the main natural accumulators of poison. They have a very bright, conspicuous color. Its purpose is to warn others that the animal is poisonous. The British very aptly called these colorful amphibians "poison arrow frogs."

Batrachotoxin is part of the secretion of the skin glands in four species of amphibians.

  1. Terrible leaf climber. It lives in the jungles of Colombia and is considered one of the most poisonous animals in the world.
  2. Bicolor leaf climber. It is the first largest and second most toxic representative of the tree frog family.
  3. Golden dart frog. It can be found in the jungle of Suriname.
  4. Kokoi frog. It is a tiny amphibian that inhabits the Rio Atrato basin.

Some insects and birds found in New Guinea also contain batrachotoxin. The poisonous community of this area includes four species of colorful beetles from the family Melyridae of the genus Choresine.

The birds that can cause batrachotoxin poisoning include:

  • blue-headed ifrit, from the genus Ifrita,
  • blackbird flycatcher, from the genus Colluricincla,
  • and seven members of the Pitohui genus.

Birds get the toxin by eating beetles from the Melyridae family. For them, the poison is not dangerous, but they accumulate it in the plumage, skin and striated muscles.

Despite the fact that studies of animals accumulating batrachotoxin have been going on for decades, there are still many unanswered questions. The source of the poison in tree frogs is still unknown. So, the tadpoles of leaf climbers do not contain toxin, and with the artificial resettlement of frogs, they lose their poisonous properties. It becomes clear that the toxicity of amphibians is associated with the terrain where they live, as well as with the habits of nutrition. But there is no complete clarity, so the question remains open.

Action on the body

Batrachotoxin is a powerful neurotoxin in its effect. It disrupts the permeability of cell membranes at sodium channels. There are many natural poisons with an affinity for these same structures. But, unlike most of them, batrachotoxin does not block sodium channels, but puts them in an “open state”. Sodium enters the cell unhindered. The toxin molecule is located inside the channel and, due to its structure, does not interfere with the penetration of small anions.

The consequence is irreversible depolarization of cells, in which the ability to transmit nerve impulses is lost. Paralysis of the motor and respiratory muscles sets in. Dysfunction of the autonomic nervous system is reflected primarily in the work of the heart, therefore, the main effect on the body of batrachotoxin is neurotoxic and cardiotoxic. The destruction of vital functions occurs immediately after the onset of the action of the poison.

Application

The pioneers of batrachotoxin and its advanced users are, of course, the indigenous people of South America. It was they who improved the hunting process using poison arrows, thereby making it faster and less dangerous. Except, of course, the risk of injury to the hunter by this arrow.

Outside the Amazon jungle, the use of batrachotoxin is limited by scientific research. It is used to study the mechanism of action of various substances on the permeability of sodium channels of cell membranes.

The use of batrachotoxin for pharmacological research is especially important. One tenth of the drugs used in medicine act on ion channels. These drugs include pain relievers and antiarrhythmics, local anesthetics. To create new, more advanced drugs, a complete understanding of the structure and mechanism of action of the channels of cell membranes is required. Scientific research is constantly adding new data to the information already available. Batrachotoxin is a valuable organic substance for studying the cell membrane and its permeability.

Poisoning with batrachotoxin

Tragedy can occur in the habitats of animals carrying poison, through direct contact with them. A similar incident is not excluded during experimental studies in which batrachotoxin is used. Both in the first and in the second case, for the occurrence of poisoning, contact of the poison with damaged skin or mucous membranes is necessary. With their integrity, the toxin cannot enter the body. So, oral administration of batrachotoxin is dangerous only if there is a defect in the mucous membrane of the gastrointestinal tract.

A characteristic feature of poisoning is the lightning-fast formation of its signs and inevitable death. The lethal dose of batrachotoxin is very small - from 2 to 7.5 μg. Therefore, the receipt of even a small amount of poison from the skin of an animal carrier or from a laboratory pipette into the human body will inevitably lead to its death.

Symptoms

Acute pain occurs at the site of contact of the poison with damaged skin or mucous membranes. Then, after a few minutes, general signs of poisoning appear. Dysfunctions of the nervous and cardiovascular systems are its typical symptoms.

Batrachotoxin causes neuronal damage, accompanied by irreversible depolarization. Clinically, this is manifested by muscle spasms, severe cramps, and then paralysis. Initial muscle weakness is replaced by complete immobility. Then paralysis of the respiratory muscles occurs.

The cardiotoxic effect of the poison is manifested by arrhythmias, extrasystoles, fibrillations.
Death occurs 10-15 minutes after the toxin enters the body, against the background of respiratory paralysis or ineffective cardiac activity.

Antidote

The treatment of batrachotoxin poisoning is still under development. The dose of poison is always close to lethal, so the time from the moment it enters the body to cardiac arrest is only 10-15 minutes. With such initial data, finding a solution to the problem is very difficult.

Scientists have already figured out that tetrodotoxin, which blocks sodium channels, can be used as an antidote to batrachotoxin. However, it is difficult to imagine that the Amazon jungle will be able to quickly find and apply the toxin of the Fugu fish in the dose necessary to neutralize the poison. It is possible that this is only the first successful step in the search for an effective antidote to batrachotoxin.

The plant poison aconitine has an effect similar to batrachotoxin on the ion channels of the cell membrane. The cardiotoxic effect of zootoxin is similar to an overdose of cardiac glycosides. On the basis of existing treatment regimens, it is possible to simulate therapy for batrachotoxin poisoning. Scientists are still hoping to create a fast-acting antidote for specific therapy.

Summing up, we recall that batrachotoxin is one of the most powerful zoological poisons known since antiquity. The range of animals that contain it is limited to South and Central America, as well as New Guinea. The indigenous people of these regions have long used poison while hunting. Batrachotoxin has neurotoxic and cardiotoxic effects. Symptoms of poisoning appear almost immediately after contact with damaged skin or mucous membranes. Paralysis of the respiratory muscles and cardiac arrest occur within a few minutes, as a result of the lightning-fast action of the toxin. The consequence of poisoning will always be fatal. Natural poisons are known that are antagonists of batrachotoxin. Unfortunately, their use as an antidote seems unrealistic. Research continues on the pharmacological use of batrachotoxin and the identification of a fast-acting antidote for poisoning with it.

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