A rare poison from South American frogs is being cited as the substance that killed Russian opposition politician Alexei Navalny in 2024. However, it is unlikely that the poison was of natural origin. What is known.
The poison of an endangered species of frog in Ecuador is being cited as the cause of Alexei Navalny's death in prison. This was determined by scientists from Germany, France, the Netherlands, Sweden and the UK. In a joint statement, they announced that traces of the chemical epibatidine were found in Navalny's tissue samples and that “this poison is the most likely cause of his death“. Navalny was in a Siberian labor camp at the time, which is why the five countries blamed Russia, which was the only one who had the opportunity to kill Navalny.
Poison-skinned frogs
Epibatidine is a poison contained in the skin of two species of poisonous South American frogs that live in the tropical forests of Ecuador. These animal species are not found in Russia, so the poison in question cannot be extracted from a natural source in the country itself, the scientists said in a joint statement released during the Munich Security Conference.
These species of amphibians feed on insects. Alkaloid chemicals that are formed during digestion are concentrated in toxins contained in the frogs' skin, which is brightly colored as a warning to predators. In the process of their evolution, the frogs have adapted to tolerate the deadly substances. Their skin contains a variety of toxins, including batrachotoxin, which causes paralysis.
A deadly substance, not a painkiller
The epibatidine found in Navalny's tissue samples was first identified by American chemist and pharmacologist John W. Daly when he extracted and analyzed a tiny amount of the toxin in the 1970s. Many poisonous substances from animals and plants are used in small amounts for medicinal purposes - for example, as a painkiller or as a possible treatment for some difficult-to-treat diseases such as cancer.
Epibatidine has also been investigated for such a use - as a non-addictive painkiller. But the toxin is so potent, and the difference between a non-lethal and a lethal dose is so small, that pharmacists quickly abandoned its use as a viable painkiller for humans. Epibatidine is known to be about 200 times more potent than morphine and can cause seizures and paralysis of the lung muscles, leading to suffocation.
Poison from Ecuador?
Scientists regularly extract venoms and toxins from animals for scientific research and to develop drugs and antidotes. But it is unlikely that Russia sent its people to Ecuador to take a sample of the venom of these rare amphibian species. Rather, the substance was synthesized in a laboratory, scientists believe.
Vil Mirzayanov, a Russian expert in analytical chemistry who has lived in the United States since the 1990s, was involved in the development of new variants of “Novichok“ after the collapse of the Soviet Union. He claims that the State Research Institute of Organic Chemistry and Technology of Russia works with natural toxins and at one time developed substances with ricin and fentanyl.
Mirzayanov believes that the epibatidine in this case was most likely produced in a laboratory: "I think that the poison was not synthesized chemically, because it is very difficult to imagine that they brought 100 grams from somewhere in South America," he told DW.
He believes that the Russian security services, which have their own modern laboratories, are responsible for using the poison.
They accuse Russia of violating an international convention
Russia rejects the accusation of the five countries that Navalny was deliberately poisoned. But in 2020, when Navalny was being treated in Germany for nerve agent poisoning, Moscow also denied any responsibility. Navalny’s widow, Yulia Navalnaya, described the five-nation findings as “scientific evidence” of his murder, saying on social media that “[Vladimir] Putin killed Alexei with a chemical weapon.”
The five countries involved in the analysis have filed a complaint with the Organization for the Prohibition of Chemical Weapons (OPCW) alleging a violation of the Chemical Weapons Convention.