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To find biologically active components of the higher fungi of Korea, the carpophores of Auricularia polytricha, a well-known edible mushroom, were extracted with 0.14M NaCl solution. The extract was successively fractionated by adding ammonium sulfate at various concentrations, and the respective precipitates were separated by centrifugation, then dialyzed and freeze-dried. When a dose of 60mg/kg of each was injected i.p. into ICR mice, the fraction which precipitated at 20% ammonium sulfate showed the highest toxicity, killing seven out of seven mice within two days. The fraction obtained at 40% ammonium sulfate showed the second highest toxicity. The two fractions were named auritoxin I and II after the genus name. However, they were shown to have nearly identical composition by physicochemical and instrumental analysis. The chemical anlaysis of aueritoxin showed 93.9% polysaccharide and 6.8% protein. The polysaccharide moiety was found to have 12.3% alpha-linkage and 87.7% beta-linkage and to be a heteromannoglucan consisting of 45.1% glucose, 43.9% mannose and 11.0% xylose. The protein moiety contained ten amino acids. The molecular weight of the toxin was 1.5 X 106 dalton by Sepharose CL-4B gel filtration. The median lethal doses of auritoxin in mice were 56.4, 157.2 and 454.6 mg/kg by i.p., s.c. and p.o. administrations, respectively. The signs of intoxication were convulsion during the first 30 minutes after the injection, coma or sleeping within an hour, tremor, lacrimation, nasal bleeding, congestion, and death in 24 hours. Among the various organs, the spleen was found to be enlarged remarkably. Human platelet aggregation was inhibited by the addition of auritoxin. The activity of malic dehydrogenase in vitro was inhibited by the toxin.
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