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BEHIND AMUSHROOMSCOURGEScientists search for the compoundsresponsible for UNEXPLAINED DEATHSFOR THE PAST 30 YEARS apparently healthy villagers in southwesternChina’s Yunnan province have been mysteriously dying.More than 260 people have been claimed by what has come to beknown as Yunnan Sudden Unexpected Death.Recent epidemiological studies have implicated a previously undescribedmushroom, named Trogia venenata Zhu L. Yang for its discoverer,in the deaths. Seeking further evidence that this mushroomis in fact responsible, a team of scientists in China have identifiedthree toxic amino acids that they believe give T. venenata its poisonousproperties ( Angew. Chem. Int. Ed., DOI: 10.1002/anie.201106502 ).Extracts of T. venenata contain γ-guanidinobutyric acid, a compoundknown to cause seizures, as well as two previously unidentifiedamino acids that are derivatives of hexynoic acid, reportsa team led by Ji-Kai Liu, of the Kunming Institute of Botany, andGuang Zeng, of the ChineseCenter for DiseaseControl & Prevention.The researcherssynthesized the newlydiscovered aminoacids and found thecompounds to be lethalin studies with mice.They also used liquidchromatography andmass spectrometry toexamine blood takenOHONH 2OHNew toxic amino acidsH 2 NNHNHOOHγ-Guanidinobutyric acidONH 2OHCOURTESY OF JI-KAI LIUfrom a victim of Yunnan Sudden Unexpected Death. They foundthat the blood and one of the newly discovered amino acids sharedsimilar fragment ions.“We are 90% certain we have solved the mystery—that thismushroom is the cause of the deaths,” Liu tells C&EN. “And we arealmost 100% certain that these three toxins are the cause of themushrooms being fatal.”But not everyone is as certain. “The contents of those toxins inthe mushroom are amazingly high,” comments Hirokazu Kawagishi,an expert on toxic mushrooms at Japan’s Shizuoka University.Therefore, he says, it is possible that these compounds are thecause of the deaths. However, Kawagishi admits to some skepticismbecause, on the basis of Liu and Zeng’s results, a personwould still have to eat about 4 kg of the fresh mushroom to consumea lethal amount of the new amino acids.“That is a staggering amount,” agrees Michael W. Beug, a retiredenvironmental chemistry professor and mycologist at EvergreenState College, in Olympia, Wash. “The fact that there have been nodeaths since 2009 when the villagers were warned not to eat thesemushrooms is pretty strong evidence that the mushrooms are involvedin the deaths,”he says, but “the toxinor combination oftoxins is yet to be adequatelyexplained.”Liu tells C&EN thathe believes a synergisticcombination of thenew amino acids withγ-guanidinobutyricacid might make themushrooms morepotent than the currentstudy suggests. Adetailed mechanismof the compounds’toxicity is still not clear, Lui says. He notes, however, that the groupis doing further research and believes that the amino acids mightinduce hypoglycemia that results in death. — BETHANY HALFORDReprinted from C&EN, Feb. 13, 2012WEBINARSLIFE SCIENCES SERIESSynthesis & Analysis ofMillions of Genomes &Nanostructures for NovelTherapies and MaterialsFATAL FUNGUS Thedeadly mushroomTrogia venenata Zhu L.Yang may have claimedhundreds of lives.Speaker:George ChurchProfessor of Genetics, Harvard MedicalSchool, Director of the Center forComputational GeneticsStrongerbonds.Date: July 12th, 2012Time: 11:00am EDTAdditional Details Available Soon!Please email CENWebinars@pubs-acs.orgfor more information.WWW.CEN-ONLINE.ORG 25 MARCH 2012