February 14, 2026

expert reaction to UK and some other European countries saying the toxin epibatidine (which is found in the skin of Ecuador dart frogs) was found in samples from Alexei Navalny’s body and highly likely resulted in his de

Scientists comment on claims made by the UK and other countries that the toxin epibatidine was found in in samples from Alexi Navalny’s body.

Prof Alastair Hay, Professor (Emeritus) of Environmental Toxicology, University of Leeds, said:

“It is claimed that Alexei Navalny was poisoned by a toxin, Epibatidine, which is normally found in certain poisonous frogs and secreted onto their skin.  The frog species is Epipedotabes tricolour, and the frogs have vivid yellow, orange or blue colours.  The bright colours may be to warn off predators.

“Epibatidine acts to inhibit nerve action by blocking what are known as nicotinic receptors.  These receptors are present in both the central and peripheral nervous systems.

“The effect of blocking these receptors is muscle paralysis and paralysis of the respiratory system.  So, breathing is blocked, and any person poisoned dies from suffocation.

“Epibatidine has been investigated as a pain killer (an analgesic) for many types of pain and for relief from painful inflammatory conditions of the lung such as asthma, pulmonary fibrosis, sarcoidosis and other lung conditions.  Epibatidine is about 100 times more potent than morphine and because of its toxicity is not used clinically.  So, it is not used to treat patients.  The presence of the toxin in anybody’s blood suggests deliberate administration.

“Epibatidine toxicity can even be increased by co- administration of certain other drugs and these combinations have been researched.

“Epibatidine is of interest to researchers studying the brain because of its unique binding to nicotinic receptors in the organ; the location of these receptors can be identified using epibatidine as a sort of probe.  Epibatidine is structurally similar, chemically, to nicotine.

“Epibatidine, as a piperidine pyridine compound, can be detected using a combination of gas chromatography and mass spectrometry.  Gas chromatography helps separate out compounds of interest and mass spectrometry breaks up chemicals into particular fragments, creating a unique fingerprint of the substance, which can then be identified.

“If epibatidine, a toxin, was indeed used to poison Alexei Navalny, this is in violation of the 1972 Biological and Toxin Weapons Convention ( BTWC) and the 1993 Chemical Weapons Convention (CWC).  The Soviet Union was a co- sponsor of the BTWC.  Russia is a signatory of both the BTWC and CWC.  If Russia used epibatidine to poison Mr Navalny it has violated two treaties it has sworn to uphold.”

https://www.gov.uk/government/news/uk-confirmsrussia-poisoned-navalny-in-prison-with-rare-toxin

https://www.gov.uk/government/news/joint-statement-by-the-uk-sweden-france-germany-and-the-netherlands-on-alexei-navalnys-death

Declared interests

Prof Alastair Hay: “No conflicts of interest.”