�ber die Giftigkeit der Fr�hjahrslorchel Gyromitra (Helvella) esculenta Fr.

Natural Toxicants in Foods

“…bprom Toth (1983). Gyromitra esculenta (false morel) is highly poisonous fresh but edible when cooked by boiling (Franke et al, 1967). Toxicity is caused by the volatile indigenous hydrazone, gyromitrin (Pyysalo and Niskanen, 1977).…”

“…Concentrations of hydrazone analogs isolated from Gyromitra esculenta are shown in Table 31. During cooking, care must be taken because highly toxie vapors also volatilize from the mushrooms (Franke et al, 1967). Boiling for 10 minutes is required to reduce hydrazone concentrations below 1 ~g/g.…”

“…The route of administration (intraperitoneal, intravenous, or oral) has essentially no influence on the toxicity of these compounds (Witkin, 1956). The difference between the no-effect amount and alethal dosage of N-methylhydrazine is small in apes (Mäkinen et al, 1977), but there is a large variation in individual human tolerances as indieated by case his tori es (Franke et al, 1967). Calculated lethai dos es for children and human adults, based on reports of false morel intoxication, are 10 to 30 Ilg/g and 20 to 50 Ilg/g, respectively (Schmidlin-Meszaros, 1974.…”

FORMATION OF TOXIC METHYLHYDRAZINE DURING COOKING OF FALSE MORELS, GYROMITRA ESCULENTA

“…), is one of the very few natural products containing hydrazones, i.e. N-methyl-N-formylhydrazones (LaRue 1977), ten of which have been identified in the fresh mushroom (List and Luft 1968;Pyysalo and Niskanen 1977).…”

“…The toxicities of N-methyl-N-formylhydrazones have been widely studied. Acetaldehyde-N-methyl-N-formylhydrazone, commonly called Gyromitrin or ethylidene gyromitrin, is the main hydrazone in the fresh mushroom and has been found t o be mainly responsible for the toxicity 296 HEIKKI PYYSALO, AIM0 NISKANEN AND A W E von WRIGHT of false morels (List and Luft 1968;Pyysalo and Niskanen 1977). The LD,,, value of ethylidene gyromitrin has been estimated to be 340 mg/kg for mice (von Wright et al 1978b), 320 mg/kg for rats and 70 mg/kg for rabbits (Makinen et al 1977), whereas the LD5 value of N-methylhydrazine for mice has proved to be much lower i.e.…”