May 25, 2009

Fatal Toxin Identified In Mushrooms

A toxin contained within a certain species of mushroom causing the deaths of seven people in Japan in recent years has been identified by scientists, Reuters reported.

In a Monday publication of Nature Chemical Biology, the researchers wrote that they pinpointed the poisonous compound in the mushroom, Russula subnigricans, and verified its toxicity by having mice ingest it. 

Cycloprop-2-ene carboxylic acid, the perpetrating toxin, only contains four carbon atoms. 

"We ascertained that this toxin causes severe rhabdomyolysis on mice ... which means that this toxin is the responsible toxin causing the mushroom poisoning," said Kimiko Hashimoto of Kyoto Pharmaceutical University and member of the research team.

The Japanese victims of this particular toxin exposure suffered the typical symptoms of poisoning including nausea, diarrhea, speech impairment, convulsions, pupil contractions, stiff shoulders and backaches, as well as the rarely observed symptom of rhabdomyoysis. 

Rhabdomyolysis is the rapid deterioration of skeletal tissues of the muscle due to muscle injury.  This results in the discharge of the protein myoglobin into the bloodstream which is severely detrimental to the kidneys. 

Myoglobin was detected in the urine of the Japanese victims.

Eating just two or three of these mushrooms would be fatal to adult humans, Hashimoto said. 

"Medical doctors who meet such cases should give care to protect the kidney. Rhabdomyolysis produces a large quantity of myoglobin, which is a heavy burden to the kidney. So, rhabdomyolysis leads to renal failure and then leads to death," Hashimoto wrote in a statement to the press. 

Other accounts of rhabdomyolysis were reported in France and Poland after victims ate another species of mushroom, the Tricholoma equestre.  But, Hashimoto determined more research was needed to accurately identify the toxin in that species. 


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