Sea anemone provides insecticides and painkillers of the future
Bad news for harmful insects, good news for humans. Researchers at the Laboratory for Toxicology and Food Chemistry have discovered that sea anemone toxin is an environmentally friendly insecticide far more potent than DDT. Moreover, it may provide the basis for a new generation of painkillers. "Are toxins friend or foe? The more we understand these toxins, the more they become less foe and more friend to humans."
Sea anemones, often mistaken for aquatic plants, are actually predatory polyps related to jellyfish. They are equipped with poisonous, harpoon-like 'nettle cells', which are used for self-protection and hunting prey. Upon contact, the anemone fires off small, poison-filled harpoons, killing its prey. Professor Jan Tytgat, head of the Laboratory for Toxicology and Food Chemistry: "The poison is a cocktail of different toxins, 'poisonous' proteins with different targets. One such toxin paralyses the nervous system by attacking the ion channels that govern its functioning. Others affect the heart or skeletal muscle tissue."
"Researcher Steve Peigneur and I investigated the effects of three toxins derived from the sea anemone. We tested them on ten types of ion channels; seven from mammals, but also three from insects. The results were spectacular to say the least: the poisons paralyse the ion channels of mammals but also, surprisingly, of insects. In other words, they are insecticides, and extremely deadly insecticides at that – many times more potent than DDT."
"Are toxins friend or foe? The more we understand these toxins, the more they become less foe and more friend to humans."
"Why would a sea anemone have a powerful weapon against insects? In principle, a sea anemone never encounters an insect in its lifetime. It seems totally evolutionarily unnecessary. One possible explanation is that sea anemones defend themselves against and feed on lobsters and shrimp. These crustaceans are evolutionarily closely related to insects."
Kill and cure
These toxins can lead to new environmentally friendly insecticides, says Professor Tytgat: "Many of the current insecticides are no longer effective. Insects have become resistant to them. This is not the case with anemone poison. Moreover, many artificial insecticides such as DDT break down slowly in nature, and they are a danger to the environment and to humans. They leave behind a mess in the body – that's one of the reasons many insecticides have been banned. Toxins produced by the sea anemone are a natural product and therefore do not have that problem."
"It is now up to the agro-industry to examine how those toxins can be made into actual insecticides. We can change the genetics of plants so that they themselves produce these toxic proteins, for example. An insect would then fall dead after feeding on the plant. That sounds spectacular, but in nature it is nothing new: the nicotine in tobacco plants also aims to kill hostile insects.”
Soon anemone poison may not only be used to keep our fields pest-free, but may also provide the basis for new drugs. "Some people do not respond to mild painkillers such as paracetamol – or even to hard narcotics such as morphine. There is a need for a new generation of painkillers. Sea anemone toxins can help. As I mentioned, we also tested the toxins on targets in mammals. They appear to have an effect on pain perception, and they act on the heart. They may also be useful in treating disorders such as epilepsy and multiple sclerosis."
Are medications derived from sea anemones a far-off dream? "Not at all," says Tytgat. "Drugs of the sort already exist today. Prialt, a drug for chronic pain, came on the market couple years ago. Its active ingredient is a toxin derived from the poison of sea snails. It may sound like science fiction, but the first breakthroughs have already been made." (See box below)
Lethal to insects, pain-easing for humans; that's quite something for such a small creature. Jan Tytgat: "In our paper, we don't call the poison of the sea anemone 'promiscuous' for nothing. It contains a cocktail of toxins, one of which attacks a very specific target in prey, another that has a more general paralysing effect. Very clever of the anemone, because that range of targets increases its chance of survival far more than pointing all defenses at a single target. This also means that resistance to the anemone poison does not build up: survivors cannot reproduce because there are simply no survivors."
"The more we understand these toxins, the more they become less foe and more friend to humans. They're a good example of how we can apply the biodiversity of Mother Nature towards a better and healthier life."
The study is the cover story in the December issue of The FASEB Journal. www.fasebj.org
POISONOUS CREATURES, HEALTHY HUMANS
The sea anemone is not the first poisonous animal to show promise in the development of new medications:
- The snake Bothrops jararaca: Captopril® for the treatment of high blood pressure
- The Gila monster, a species of venemous lizard: Byetta® for the treatment of type 2 diabetes
- The sea slug Conus magus: Prialt® for the treatment of chronic pain