The Right Chemistry: Getting to the bottom of a criminal poisoning

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After a young Japanese woman died suddenly, it took some serious chemical sleuthing to unravel the mystery and bring her husband to justice.

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It was a real puzzler. On autopsy, Dr. Youkichi Ohno could find no evidence of any prior condition to explain why the 33-year-old Japanese woman had died of an apparent heart attack that day in 1986. While out with her friends, the woman had been overcome by nausea and had complained of a loss of feeling in her extremities. When she vomited violently, her friends called for help, but in the ambulance the unfortunate woman developed an irregular heartbeat that could not be corrected by defibrillation and she died. Because the death could not be readily explained, the police were informed.

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Upon questioning, the victim’s husband revealed that he had been married twice before and both wives had died, one of a heart attack the other of myocarditis. That was curious, and suspicions were raised further when it was discovered that the husband had recently insured his wife’s life for a staggeringly large sum. Ohno now suspected poisoning and his thoughts turned to aconite, a rapidly acting toxin known to cause ventricular fibrillation and paralysis.

Aconitum napellus is a perennial herb commonly known as monkshood because its purple flowers resemble the hoods worn by monks. All parts of the plant contain extremely toxic alkaloids, with aconitine leading the pack. Swallowing just two milligrams of these compounds or one gram of the root can be fatal. The toxicity of a crude extract of the plant, known as “aconite,” was already known to the Romans, who used it as a method of execution. We know that Shakespeare was aware of its toxicity, specifically mentioning aconitum in Henry IV. It is likely also the poison he had in mind with which a lovestruck Romeo committed suicide.

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While aconite can account for paralysis and irregular heartbeat, there were a couple of problems with the poisoning theory. There was no way at the time to test blood or tissue samples for the tiny amounts of alkaloids that could have caused death. And there was also an issue with the time frame. The last time husband and wife were together was about an hour and a half before her collapse; aconite’s effects would have been manifested in a much shorter period of time.

Luckily, the police decided to keep some blood samples and just nine months later that foresight paid off. A method of detecting very small amounts of Aconitum alkaloids using the combined techniques of gas chromatography and mass spectrometry was worked out, and they were indeed detected in the stored samples. Still, this was not enough to connect the husband to the poisoning because of the time problem. But the police kept digging, and four years later discovered that the husband had purchased a bunch of Aconitum napellus plants. That led to his arrest, indictment and then ultimately, conviction, for murder.

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The investigation revealed something else, as well. The accused had also purchased some pufferfish, a delicacy in Japan. Since the species harbours the potent poison tetrodotoxin, Japanese chefs are specially trained to remove the toxic organs before serving “fugu,” as the dish is known. When authorities tested the victim’s stored blood, they found tetrodotoxin.

Now Dr. Ohno had an idea. He knew that the toxic effects of aconitine are due to enhancing the influx of sodium ions into nerve cells, and that tetrodotoxin kills by starving nerve cells of sodium. Could the tetrodotoxin delay the action of aconitine? Could these toxins act in an antagonistic fashion? A series of experiments on mice showed that the toxic effects of aconitine were markedly reduced by the oral co-administration of tetrodotoxin. Based on the evidence presented, the husband was found guilty of murder and sentenced to life in prison. While he admitted that he was interested in chemistry and had bought the plants and the pufferfish to experiment with, he maintained that he had nothing to do with his wife’s demise.

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Was he a clever chemist who had found a way to delay the action of aconitine and deflect suspicion from himself, or was he trying to mix the two potent toxins to ensure a quick death but just happened to accidentally postpone it? We will never know, but his murderous plan did shed light on the combined effects of aconitine and tetrodotoxin.

While there have been many other criminal poisonings with aconite, including a widely celebrated 2010 case in England in which a scorned Mrs. Lakhvir Singh murdered the lover she had been having an extra-marital affair with, there have also been a number of accidental poisonings. In Traditional Chinese Medicine, aconite is used, among other conditions, to treat faint pulse, impotence, and “Yang deficiency.” If not properly detoxified by toasting or steaming, such aconite preparations can be very dangerous. Aconite is also used in homeopathy to treat conditions ranging from respiratory infections and toothache to vertigo and kidney stones. Since according to the tenets of homeopathy these preparations are diluted to the extent that they only contain the “memory” of aconite, they are harmless. They also lack any evidence of efficacy.

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Finally, we note that the ancient Greeks used juice from monkshood to poison arrows, and historically aconite was also used to kill carnivores such as panthers and wolves with poisoned bait. Hence the alternate name for the herb, “wolfbane.” There is yet one other connection. Should you be worried about werewolves, you might consider keeping a few sprigs of wolfbane around. They are said to keep lycanthropes at bay.

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Joe Schwarcz is director of McGill University’s Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.

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