There are many ways to get intoxicated; there are chemical elements that are deadly toxic to humans, either because of the way they interact with the body or because of their high radioactivity. There are also synthetic toxins that do not appear in nature, and can only be found in a laboratory, but many toxins are substances produced by living things. Some animals, plants, protists or bacteria are authentic living chemical laboratories that produce the most varied toxins.
In living beings we can find powerful poisons, such as tetradotoxin present in fugu fish, conantokina-p present in cone worms, or cyanide derivatives in a good number of seeds. Or even more toxic substances.
5. Strychnine
A tree well known for its high toxicity grows in the tropical forests of Southeast Asia and northern Australia. Commonly known as nux vomica , the seeds of Strichnos nux-vomica are carriers of two powerful toxins: brucine and strychnine .
Strychnine is considered the fifth most potent biological poison in the world. It is a neurotoxic alkaloid , which attacks the central nervous system. It causes a general contraction of the body’s muscles, and causes convulsions that can last up to 2 or 3 hours, the time it takes for the victim to die. It is estimated that 25 µg of strychnine is the lethal dose for a mouse, and for human adults it is estimated between 50 and 100 mg.
It is a toxin that is rapidly absorbed through the mucous membranes and the gastrointestinal tract , however, it does not occur through the skin. Once it enters the body, the toxin is rapidly distributed throughout the tissues, and is metabolized in a very short time. Its elimination in the urine is very low (no more than 20%).
4. Maitotoxin
One of the most powerful poisons in the world is not found in animals or plants, but in small, single-celled aquatic organisms. In traditional classifications they are grouped as algae, although they are evolutionarily closer to other organisms traditionally considered protozoa, such as the genus Plasmodium (the parasite that causes malaria) than to true algae. We are talking about dinoflagellates.
Dinoflagellates are peculiar organisms; many are photosynthetic, but also consume prey by phagocytosis; Organisms capable of carrying out both actions are called mixotrophs . Many have a covering of cellulose , called theca, which covers the cell body and protects it, and all have two flagella , one that surrounds the organism like a belt, and another long one that it uses to propel itself.
When an unusually high number of dinoflagellates concentrate in a body of water, it turns a reddish color. This phenomenon, reminiscent of a biblical curse, is called ” red tide “, and can cause poisoning, both by drinking the water, or by consuming animals that live there, especially if they are filter feeders, such as mussels or clams. , because they retain the dinoflagellates in their body.
The fourth most potent biological toxin is produced by a dinoflagellate: Gambierdiscus toxicus . Maitotoxin is a molecule made up of 32 carbon rings , and is one of the largest and most complex non-protein, non-polysaccharide biomolecules. It is a powerful toxin that causes heart failure and death in a very short time , both by ingestion, by inhalation and even by contact. It is estimated that 2.5 ng of maitotoxin is enough to kill a mouse. The lethal dose in humans has not been estimated.
3. Batracotoxina
Batrachotoxin is the most potent known animal poison . It is a neurotoxic alkaloid that induces irreversible depolarization of nerves and muscles, and can lead to paralysis, fibrillation, and heart failure. It is excreted through the skin of dart frogs of the genus Phyllobates , native to Colombia, and also by some birds from New Guinea . It is so potent that as little as 10 ng of toxin can be lethal to a mouse, and between 100 and 200 µg to a human.
A curious fact is that frogs bred in captivity do not produce batrachotoxin, so it is suspected that the toxin is not produced by their metabolism, but that they probably obtain it through their diet . Beetles of the genus Choresine , which produce toxins from the same group, although in much lower concentration, have been proposed as the putative source of the toxin. If this hypothesis is true, frogs and birds would sequester the toxin, metabolize it to batrachotoxin, to which they are immune, and concentrate it, excreting it through the skin.
2. Ricin
When one living being is attacked by another, it usually follows a response called hyperarousal. It is described as a fight or flight reaction, that is, the organism that perceives the attack tries to fight back or avoid the attack.
Plants cannot flee, in the literal sense of the term, nor do they have a way of responding with an active attack, so they often opt for pre-emptive defense. Some plants generate structures that repel the ‘attacker’: they have spines or spurs as a way of avoiding the attack. It would be his way of “escape”. But others opt for biochemical defense. And it is that plants have an extraordinarily complex secondary metabolism, and are capable of synthesizing a wide range of chemical substances with which to “fight” against their attacker .
Of all of them, the one with the deadliest defense is the castor bean ( Ricinus communis ). This plant has come to synthesize the deadliest plant toxin, ricin , the most poisonous substance produced by a eukaryote , and the second most poisonous of all living things. Unlike strychnine, batrachotoxin, or maitotoxin, which are relatively two alkaloids and one chain of carbon rings, ricin is a protein . Its toxicity occurs at the cellular level, inhibiting protein synthesis . The symptoms are different depending on the route of exposure, but in any case, a minimum dose can be lethal.
1. Botulinum toxin
The deadliest toxin produced by a living being is botulinum, produced by the bacterium Clostridium botulinum . It is an anaerobic bacterium , it only grows in the absence of oxygen, but it is practically ubiquitous. It can grow in foods, especially preserves, as long as it does not come into contact with air. During the fermentation process, bacteria produce gas, so if a canning container were contaminated, it would appear swollen.
Botulinum toxin is a neurotoxin of a protein nature , only a few nanograms are enough to kill an adult. It causes muscle and nerve paralysis by preventing the release of the neurotransmitter acetylcholine; an intoxication that has its own name: botulism .
A small amount of the toxin is found in ‘botox’ , which paralyzes muscles to minimize wrinkles. With very carefully measured doses, it is also used as a muscle antispasmodic.
References:
Dumbacher, J. P. et al. 2004. Melyrid beetles ( Choresine ): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds. Proceedings of the National Academy of Sciences, 101(45), 15857-15860. DOI: 10.1073/pnas.0407197101
EFSA. 2008. Ricin (from Ricinus communis) as undesirable substances in animal feed – Scientific Opinion of the Panel on Contaminants in the Food Chain. EFSA Journal, EFSA Journal. DOI: 10.2903/j.efsa.2008.726
Montecucco, C. et al. 2005. Botulinal neurotoxins: revival of an old killer. Current Opinion in Pharmacology, 5(3), 274-279. DOI: 10.1016/j.coph.2004.12.006
Stoecker, D. K. 1999. Mixotrophy among Dinoflagellates. Journal of Eukaryotic Microbiology, 46(4), 397-401. DOI: 10.1111/j.1550-7408.1999.tb04619.x
National Center for Biotechnology Information (2022). PubChem Compound Summary for CID 441071, Strychnine; CID 71460273, Maitotoxin; and CID 6324647, Batrachotoxin.
