Elapidae is a family of poisonous snakes that includes the cobras. They are recognized for their unusual looks, deadly venom, and the capacity to lift the front portion of their bodies when attacked, generating a distinctive hood shape.
There are several species of cobras that may be found across the world, some of which are well-known, such as the Indian cobra, the king cobra, and the spitting cobra.
Cobras have long been a source of interest and threat because of their recognisable hooded look and lethal venom. The venom of these snakes is a sophisticated concoction of poisons intended to seize food and prevent predators, which is one of its most infamous features.
Cobras may inject their prey with venom by using their teeth (fanga) and venom glands. Although the ingredients of cobra venom vary depending on the species, they frequently include strong neurotoxins that can result in paralysis and, in extreme circumstances, death. The main purpose of the venom is to paralyse and devour their victim.
Components of Cobra Venom
Each toxin in cobra venom plays a particular function in immobilising prey and possible dangers, making it a lethal mixture.
- Neurotoxins: These poisons affect the neurological system and block nerve impulses to the point of paralysis. Cobras utilise neurotoxins to quickly paralyse their victim. A cobra bite can cause respiratory discomfort, muscular weakness, and, if left untreated, death from respiratory failure.
- Cytotoxins: At the bite site, cytotoxins cause tissue necrosis by damaging and destroying cells. Pain, edema, and potentially serious local tissue damage resulting from this.
- Cardiotoxins: Cardiotoxins, which are found in some cobras and harm the heart and circulatory system, can cause irregular heartbeats, cardiac arrest, and even death.
- Enzymes: Cobra venom contains a variety of enzymes that help in digestion by dissolving the prey’s tissues. These enzymes may potentially be a factor in the biting site’s localised tissue damage.
Action of Cobra Venom
A cobra injects its victim with poison through its fangs when it strikes. The victim is rendered helpless when the poison spreads through its system quickly. Since cobras are known to devour quite big meals compared to their own body size, this immobilisation enables the cobra to swallow its victim in whole.
In cobras, the poison is delivered quite effectively. With the help of their hollow fangs, they may quickly and efficiently catch their victim by injecting poison deep into the tissues.
Toxin Variants in Cobra Venom
- Alpha (α)-Neurotoxins: The most well-known neurotoxins in cobra venom include Alpha-neurotoxin. Nicotinic acetylcholine receptors (nAChRs) in the neuromuscular junction are the target of alpha-neurotoxins. They attach to these receptors and obstruct the flow of nerve impulses to the muscles, resulting in paralysis. Both prospective attackers and prey may be paralysed by this condition.
- Beta (β)-Neurotoxins: The Voltage-Gated Sodium Channels (VGSC) in nerve cells are the main target for beta-neurotoxins. By obstructing these channels, the toxin prevents nerve cells from working, which can cause paralysis and, in more severe cases, respiratory failure. Beta-neurotoxins are particularly potent and can have life-threatening effects.
- Phospholipase A2 (PLA2) Toxins: Some cobra venoms contain PLA2 toxins, which can have neurotoxic effects but are not always neurotoxic. These toxins harm cells and cause inflammation by rupturing phospholipids in cell membranes. This damage can indirectly affect the nervous system by causing pain and swelling at the bite site.
- Three-finger Toxins (3FTx): Three-finger toxins, which can have a variety of consequences, including neurotoxicity, are produced by certain cobras and are found in their venom. These poisons may obstruct the signalling of nerve cells and cause paralysis.
- Cardiotoxins: Cardiotoxins can be neurotoxic even though their main effects are on the circulatory system. They can cause cardiac arrhythmias by interfering with the electrical signalling in the heart. By influencing blood flow and oxygen supply to diverse tissues, these toxins can have an indirect effect on the neurological system.
It is a type of ‘±-neurotoxin, a neurotoxic protein that is known to bind irreversibly and competitively to the Acetylcholine receptor found at the neuromuscular junction, causing paralysis, respiratory failure and death in the victim. Structure Source: PubChem
α-Bungarotoxin
It is a strong neurotoxin that is present in the venom of several elapid snakes, especially the many-banded krait (Bungarus multicinctus), from which it derives its name. It can also be discovered in the venom of certain cobras and several other snake species.
High in toxicity, bungarotoxin works as a competitive antagonist at the nervous system’s nicotinic acetylcholine receptors (nAChRs). It can impede the activity of acetylcholine, a neurotransmitter responsible for sending nerve impulses to muscles, by selectively binding to nAChRs at the neuromuscular junction. If left untreated, this causes muscular paralysis and can be fatal.
In medical research and drug development: Numerous studies on bungarotoxin have been conducted in the fields of neuroscience and neuropharmacology. It serves as a research tool to comprehend the composition and operation of nAChRs, which is crucial for the investigation of neuromuscular disorders, neurotransmission, and pharmaceutical development.
The development of drugs and treatments for a number of medical conditions, including neuromuscular disorders, myasthenia gravis, and some autoimmune diseases, has been aided by research into the mechanism of action and interaction of -bungarotoxin with nAChRs, despite the fact that the substance itself is highly toxic and unsuitable for therapeutic use.
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Approved drugs
α-Cobrotoxin: α-Cobrotoxin is a substance extracted from the venom of the Chinese cobra (Naja atra). It is a 3FTx α-neurotoxin that binds nicotinic acetylcholine receptors at the neuromuscular junction. It has reported side effects due to hyper bioactivity, which could lead to conditions like respiratory arrest. This can be also used as a painkiller, and for Multiple sclerosis, a genetic disorder.
References
1. “Higher Taxa in Extant Reptiles.” THE REPTILE DATABASE, 27 Dec. 2022, www.reptile-database.org/db-info/taxa.html#Ser. Accessed 6 Sept. 2023.
2. “Effects of Cobra Venom.” University of Michigan, websites.umich.edu/~elements/web_mod/cobra/venom.html. Accessed 7 Sept. 2023.
3. Tan, Choo Hock, et al. “Snake Venomics and Antivenomics of Cape Cobra (Naja Nivea) from South Africa: Insights into Venom Toxicity and Cross-Neutralization Activity.” Toxins, vol. 14, no. 12, Dec. 2022, p. 860. Crossref, https://doi.org/10.3390/toxins14120860.
4. Oliveira, Ana L., et al. “The Chemistry of Snake Venom and Its Medicinal Potential.” Nature Reviews Chemistry, vol. 6, no. 7, 2022, pp. 451-469, https://doi.org/10.1038/s41570-022-00393-7. Accessed 11 Sept. 2023.
5. Bordon, Karla D., et al. “From Animal Poisons and Venoms to Medicines: Achievements, Challenges and Perspectives in Drug Discovery.” Frontiers in Pharmacology, vol. 11, 2020, p. 553397, https://doi.org/10.3389/fphar.2020.01132. Accessed 11 Sept. 2023.
6. Vogel, Carl. “Cobra Venom Factor.” Encyclopedia of Immunology (Second Edition), 1997, pp. 586-589, https://doi.org/10.1006/rwei.1999.0154. Accessed 11 Sept. 2023.
7. Waheed Humera *, Moin F. Syed and Choudhary I. M., Snake Venom: From Deadly Toxins to Life-saving Therapeutics, Current Medicinal Chemistry 2017; 24(17). https://dx.doi.org/10.2174/0929867324666170605091546
8. Nys, Mieke, et al. “The Molecular Mechanism of Snake Short-chain α-neurotoxin Binding to Muscle-type Nicotinic Acetylcholine Receptors.” Nature Communications, vol. 13, 2022, https://doi.org/10.1038/s41467-022-32174-7. Accessed 10 Sept. 2023.
9. National Center for Biotechnology Information. “PubChem Compound Summary for CID 44264212, alpha-Bungarotoxin” PubChem, https://pubchem.ncbi.nlm.nih.gov/compound/44264212. Accessed 12 September 2023.
10. “7LUW.” Protein Data Bank (RCSB-PDB), 14 Apr. 2014, www.rcsb.org/structure/7luw. Accessed 12 Sept. 2023.
Author: Achuth B S
Edited by: Ajmal Azeem
Published: 15-September-2023
Updated: 16-September-2023, 23:10
Graduated from the University of Kerala with B.Sc. Botany and Biotechnology. M.Sc. Biotechnology from the University of Kerala. Attended certificate course in Artificial Intelligence for Everyone from Deeplearning.AI, Influenza Prevention and Control from World Health Organization. Attended workshops related to Bioinformatics at the University of Kerala. 3 years of experience in website management. Experience in WordPress, Blogger, Google Analytics, and Google Search Console.
