A known critic of Vladimir Putin was hospitalized after a possible poisoning, Axios reported. Alexei Navalny’s doctor rebuked reports that Navalny had suffered an allergic reaction while in jail. How do certain poisons affect the body differently?
According to Axios, Alexei Navalny is an anti-corruption lawyer and “Russian opposition activist” whose actions have led to his arrest and incarceration multiple times. Navalny’s official website even said that in 2017, he was attacked with acid, which was thrown in his face and left him partially blind. If his doctor’s current claims are true, the resilient Russian activist has survived two direct chemical attacks on his person. Strikingly, poisons affect the body in varied ways and to different, horrific extents.
Poisons, Toxins, and Venoms
When we hear the words poison, toxin, and venom, we may think of them as one and the same. In reality, each word is a subset of the previous word, in a hierarchy. “Poisons can be thought of as any chemical that disrupts the normal biological functions of a living system, like arsenic and lead,” said Dr. Ron B. Davis, Jr., Associate Teaching Professor of Chemistry at Georgetown University. “Toxins disrupt biological systems but are created by another biological system. A venom is most simply defined as a toxin that one animal transfers to another by injection, either as a predatory or defensive tactic.”
How Arsenic Kills
Arsenic was the poison of choice from the 1st century A.D. to the Renaissance. So how did it work? “Phosphates serve multiple, critical roles in biology, including holding your DNA together, as well as playing roles in storage and use of energy,” Dr. Davis said. “It’s that last function that makes you and me vulnerable to arsenic.”
Dr. Davis said that adenosine triphosphate (ATP) is a compound that helps your body maintain energy storage and it features three phosphate groups in a chain. “Removal of a phosphate group creates ADP—and a considerable amount of chemical energy that your body taps to keep itself going,” he said. Arsenic’s electron configuration makes it a very similar ion to phosphate. “So similar that it can replace phosphate in ATP molecules, causing a malfunction in the energy storage and transmission process in your body.”
Hemlock and Snake Bites
Plants like hemlock produce toxins—specifically, the molecule coniine. “Coniine acts like many drugs, binding to proteins in your body that need to function properly to keep you alive,” Dr. Davis said, adding that coniine impersonates nicotine in your body. “Both of these molecules bind to receptors that process ions in your body. Usually, the cause of death is respiratory paralysis, as the muscles that flex to fill and empty the lungs fall still.”
According to Dr. Davis, when we smoke a cigarette, only a small fraction of the nicotine is transferred to our bodies. Extracting and injecting it, however, would be far more dangerous. He also mentioned a chemical extracted from the glands of the Poison Dart Frog called batrachotoxin. Technically it isn’t a venom, since the frog doesn’t inject it into other animals like a scorpion or snake does, but its potency is such that a single drop on a hunter’s arrow can take down large game with one shot.
Venoms attack special proteins in muscular cell walls called ion channels. Ion channels selectively transmit or stop various ions that lead to muscle contraction. One example of this venom is the peptide chlorotoxin. “The chlorotoxin seeks out and binds to the opening to a victim’s ion channel proteins through a set of very specific sidechain interactions between those two molecules,” Dr. Davis said. “Acting not unlike a drain plug, chlorotoxin caps off ion channels and cuts off the ion-superhighway that the cell uses to manage energy. No energy means no muscle contraction.” And unfortunately, no muscle contraction means no breathing.
The exact chemical compound Alexei Navalny’s doctor detected in him has yet to be determined, so it may be a poison from an inorganic material or a toxin from a biological organism. For now, Navalny has survived.
Dr. Ron B. Davis, Jr. contributed to this article. Dr. Davis is an Associate Teaching Professor of Chemistry at Georgetown University, where he has been teaching introductory organic chemistry laboratories since 2008. He earned his Ph.D. in Chemistry from The Pennsylvania State University.