Considerations on the carcinogenicity of the mushroom poison gyromitrin and its metabolites

Mushroom Toxins: Chemistry and Toxicology

Mushroom consumption is a global tradition that is still gaining popularity. However, foraging for wild mushrooms and accidental ingestion of toxic mushrooms can result in serious illness and even death. The early diagnosis and treatment of mushroom poisoning are quite difficult, as the symptoms are similar to those caused by common diseases. Chemically, mushroom poisoning is related to very powerful toxins, suggesting that the isolation and identification of toxins have great research value, especially in determining the lethal components of toxic mushrooms. In contrast, most of these toxins have remarkable physiological properties that could promote advances in chemistry, biochemistry, physiology, and pharmacology. Although more than 100 toxins have been elucidated, there are a number of lethal mushrooms that have not been fully investigated. This review provides information on the chemistry (including chemical structures, total synthesis, and biosynthesis) and the toxicology of these toxins, hoping to inspire further research in this area.

Clinical symptomatology and management of mushroom poisoning

Among poisonous mushrooms, a small number may cause serious intoxication and even fatalities in man. Humans may become symptomatic after a mushroom meal for rather different reasons: (1) ingestion of mushrooms containing toxins, (2) large amounts of mushrooms may be hard to digest, (3) immunological reactions to mushroom-derived antigens, (4) ingestion of mushrooms causing ethanol intolerance, and (5) vegetative symptoms may occur whenever a patient realizes that there might be a possibility of ingestion of a toxic mushroom after a mushroom meal. Based on the classes of toxins and their clinical symptoms, seven different types of mushroom poisoning can be distinguished: (1) phalloides, (2) orellanus, (3) gyromitra, (4) muscarine, (5) pantherina, (6) psilocybin, and (7) gastrointestinal mushroom syndrome. Two other entities of adverse reactions to mushrooms are (8) coprinus and (9) paxillus syndrome. Phalloides, orellanus, gyromitra and paxillus syndrome may lead to serious poisoning, which generally requires treatment of the patient in an intensive care unit. Diagnosis of mushroom poisoning is primarily based on anamnestic data, identification of mushrooms from leftovers of the mushroom meal, spore analysis, and/or chemical analysis. Therapeutic strategies include primary detoxification by induced emesis, gastric lavage and activated charcoal, secondary detoxification, symptomatic treatment and rarely specific antidotes. Owing to progressing fulminant hepatic failure, lethality associated with phalloides syndrome is still high (5-20%). Basic treatment includes administration of silibinin and penicillin G, although controlled studies on its therapeutic efficacy are still lacking. In serious phalloides syndrome, orthotopic liver transplantation has to be considered. Fortunately, the prognosis in most other mushroom poisonings is excellent.

Poisoning by Gyromitra esculenta--a review

Gyromitra esculenta (Pers.: Fr.) Fr. and a few other mushrooms have caused severe poisonings and even deaths in humans. Clinical data are characterized primarily by vomiting and diarrhoea, followed by jaundice, convulsions and coma. Gastrointestinal disorders distinguish this poisoning. Frequent consumption can cause hepatitis and neurological diseases. The species of concern are mainly G. esculenta and G. gigas (Kromb.) Cooke (non Phill.). Nevertheless, recent advances in chromatography, biochemistry and toxicology have established that other Ascomycetes species also may prove toxic. Gyromitrin (acetaldehyde methylformylhydrazone, G) and its homologues are toxic compounds that convert in vivo into N-methyl-N-formylhydrazine (MFH), and then into N-methylhydrazine (MH). The toxicity of these chemicals, which are chiefly hepatotoxic and even carcinogenic, has been established through in vivo and in vitro experiments using animals, cell cultures and biochemical systems. When we consider the chemical nature and the reactivity of these natural compounds, we suggest that chemical and biochemical mechanisms may explain their intrinsic biological activity.