Rare dart frog toxin linked to Russian opposition leader Navalny’s death

Russian opposition figure Alexei Navalny was killed using a highly lethal toxin derived from South American poison dart frogs, the UK and several European allies have said.

The UK Foreign Office told the BBC that traces of epibatidine were detected in samples taken from Navalny’s body. The toxin was deemed highly likely to have caused his death in a Siberian penal colony two years ago.

In a joint position, the allies stated that only the Russian state had the “means, motive and opportunity” to deploy such a substance.

The Kremlin rejected the findings, with the Russian state news agency Tass quoting officials as describing the claims as “an information campaign.”

What is epibatidine?

Epibatidine is a powerful natural neurotoxin first isolated from the skin of the Ecuadorian poison dart frog, according to toxicology expert Jill Johnson.

She told BBC Russian that the compound is “200 times more potent” than morphine.

The toxin occurs naturally in certain wild dart frogs in South America and can also be manufactured in laboratory settings. However, frogs kept in captivity do not produce epibatidine, and the toxin is not naturally found in Russia, European allies noted.

Among the species known to secrete the toxin through their skin are Anthony’s poison arrow frog and the phantasmal poison frog.

Although researchers have explored epibatidine’s potential as a painkiller and as a treatment for painful inflammatory lung diseases, it has never been approved for clinical use due to its extreme toxicity.

How the poison affects the body

Epibatidine acts on nicotinic receptors in the nervous system, Johnson explained.

By overstimulating these receptors, the toxin can trigger muscle twitching, paralysis, seizures, slowed heart rate, respiratory failure and ultimately death — if administered in a sufficient dose.

Alastair Hay, professor of environmental toxicology at the University of Leeds, told the PA news agency that the toxin can block breathing, meaning “any person poisoned dies from suffocation.”

He added that the detection of the toxin in someone’s blood strongly suggests deliberate administration.

Hay also noted that epibatidine’s toxicity can be heightened when combined with certain other drugs, and such combinations have been the subject of research.

How rare is the substance?

Johnson described epibatidine as extremely rare, confined to a single geographic region and present only in trace amounts.

The frog referenced by UK officials is understood to be Anthony’s poison arrow frog, a species native to Ecuador and Peru.

These frogs generate the chemical by consuming specific foods that enable them to produce alkaloids — organic compounds that form epibatidine — which then accumulate in their skin. If their diet changes, their reserves of the toxin diminish.

“Finding a wild frog in the right place, eating exactly the food needed to produce the right alkaloids, is almost impossible… almost,” Johnson said.

She added that the method would be an extraordinarily rare form of human poisoning. “The only other cases of epibatidine poisoning I know of were laboratory-based and non-fatal.”

By Tamilla Hasanova