Toxic Effects of Amanitins: Repurposing Toxicities toward New Therapeutics.

The consumption of mushrooms has become increasingly popular, partly due to their nutritional and medicinal properties. This has increased the risk of confusion during picking, and thus of intoxication. In France, about 1300 cases of intoxication are observed each year, with deaths being mostly attributed to Amanita phalloides poisoning. Among amatoxins, α- and ß-amanitins are the most widely studied toxins. Hepatotoxicity is the hallmark of these compounds, leading to hepatocellular failure within three days of ingestion. The toxic mechanisms of action mainly include RNA polymerase II inhibition and oxidative stress generation, leading to hepatic cell apoptosis or necrosis depending on the doses ingested. Currently, there is no international consensus concerning Amanita phalloides poisoning management. However, antidotes with antioxidant properties remain the most effective therapeutics to date suggesting the predominant role of oxidative stress in the pathophysiology. The partially elucidated mechanisms of action may reveal a suitable target for the development of an antidote. The aim of this review is to present an overview of the knowledge on amanitins, including the latest advances that could allow the proposal of new innovative and effective therapeutics.

Intravenous rifampicin use in the management of amanita phalloides toxicity.

Context: Amanita phalloides related toxicity from amatoxins can result in acute liver and multi-organ failure and is responsible for 90% of all mushroom poisoning death. However, more evidence is needed in regards to different management strategies.Case details: We present two cases of amanita mushroom ingestion who were treated with intravenous rifampicin.Discussion: Further study is needed to establish the efficacy and role of rifampicin in amatoxin related mushroom poisoning.

Co-ingestion of amatoxins and isoxazoles-containing mushrooms and successful treatment: A case report.

Mushroom poisonings occur when ingestion of wild mushrooms containing toxins takes place, placing the consumers at life-threatening risk. In the present case report, an unusual multiple poisoning with isoxazoles- and amatoxins-containing mushrooms in a context of altered mental state and poorly controlled hypertension is presented. A 68-year-old female was presented to São João hospital (Portugal) with complaints of extreme dizziness, hallucinations, vertigo and imbalance, 3 h after consuming a stew of wild mushrooms. The first observations revealed altered mental state and elevated blood pressure. The examination of cooked mushroom fragments allowed a preliminary identification of Amanita pantherina. Gas chromatography-mass spectrometry (GC-MS) showed the presence of muscimol in urine. Moreover, through high-performance liquid chromatography-ultraviolet detection (HPLC-UV) analysis of the gastric juice, the presence of α-amanitin was found, showing that amatoxins-containing mushrooms were also included in the stew. After 4 days of supportive treatment, activated charcoal, silybin and N-acetylcysteine, the patient recovered being discharged 10 days post-ingestion with no organ complications. The prompt and appropriate therapy protocol for life-threatening amatoxins toxicity probably saved the patient's life as oral absorption was decreased and also supportive care was immediately started.

In vitro toxicity test of poisonous mushroom extracts with isolated rat hepatocytes.

Effects of poisonous mushroom extracts on isolated rat hepatocytes were studied. Though no significant decrease in the cell viability was observed during the incubation of hepatocytes with the extracts at a concentration of 5% (v/v) of Amanita abrupta, A. gymnopus, and A. virosa caused marked decreases in the intracellular glutathione content in sharp contrast to the extracts of A. volvata and A. flavipes. Comparative toxicity tests were carried out for the effects of the extract of A. abrupta, dl-propargylglycine, and alpha-amanitin. The extract of A. abrupta at a concentration of 1% (v/v) caused a marked decrease in the glycogen content, a noticeable elevation in the phosphorylase alpha activity, and a slight acceleration of lipid peroxidation in the hepatocytes. Although dl-propargylglycine decreased the intracellular glutathione content progressively with the incubation time, a significant effect of the chemical on lipid peroxidation and the glycogen content was observed only after prolonged incubation at a concentration of 5 mM. On the other hand, alpha-amanitin exerted a little effect on the hepatocytes at 1 microM. These results have indicated that the intoxication by the extract of A. abrupta on the hepatocytes might not due to independently each component, dl-propargylglycine and alpha-amanitin, but combined effect of these components or unidentified substances.

The potential use of cultured hepatocytes in predicting the hepatotoxicity of xenobiotics.

1. A protocol is proposed for screening for hepatotoxicity of xenobiotics in vitro in which hepatocytes exposed to the compounds are evaluated for both cytotoxic and metabolic effects. Four established hepatotoxins have been studied. 2. alpha-Amanitin at 1.5 pg/mg cell protein inhibited RNA synthesis by 93% and reduced albumin synthesis to 56% of the control after 13 h treatment. 3. D-Galactosamine at 40 microM inhibited glycogen synthesis by 31%, glucuronidation of p-nitrophenol by 13% and albumin synthesis by 10%, and produced an increase in cytosolic enzyme leakage. 4. Thioacetamide decreased ureogenesis after 24 h of treatment at 230 microM (31% inhibition) and after 48 h at 2.3 microM (25% inhibition). 5. Ultrastructural alterations of hepatocytes were found after 48 h exposure to 1 mM acetaminophen and were preceded by extensive leakage of the enzymes GOT and LDH. Membrane damage was observed after 24 h exposure to 0.1 mM acetaminophen.

Ethanol diminishes the toxicity of the mushroom Amanita phalloides.

Survival of mice after lethal doses of a lyophilizate from Amanita phalloides ('death cap') was markedly increased by single doses of ethanol applied 30 min before or 5 min after the mushroom. Hepatic histopathological damage (confluent necrosis) was largely prevented. Acute, but not chronic, consumption of ethanol may thus influence favorably the outcome of death cap poisoning and should be taken into consideration in the evaluation of therapeutic measures.

[Mushroom poisoning in childhood]. / Zur Problematik der Pilzvergiftungen im Kindesalter.

The authors describe frequency and importance of poisoning by Amanita phalloides. There are demonstrated the different toxins and their biochemical properties. The typical clinical symptoms of the intoxication by Amanita phalloides with vourse in two phases (1. gastrointestinal phase, 2. hepatonephrotic phase) are shown. The possibilities of diagnostic and differentialdiagnostic and the problems of therapy are discussed. It is pointed out, that in a modern treatment there must be given Penicillin-G-Natrium in high dosage as early as possible, also in cases of questionableness. Hemodialysis is only of effect till 40 hours after ingestion of Amanita.

Toxic effects of phallolysin from amanita phalloides.

Phallolysin, a protein from Amanita phalloides with cytolytic effects in vitro, was highly toxic when given intravenously to rats, mice, rabbits and guinea pigs: i.v. LD50 in rats was 85 Haemolytic Units (HU)/kg, corresponding to 0.05 mg protein/kg b.w. Death ensued from intravascular haemolysis. In rats large doses (600 HU/kg b.w.) caused cardiac death within a few minutes due to liberation of potassium from lysed cells. The serum contained lethal concentrations of potassium. There was also histological evidence of severe renal damage as a result of the haemolysis. In addition, phallolysin directly damaged the isolated guinea pig heart and the isolated rat liver, probably by its action on membranes. Given by mouth, phallolysin was not poisonous to rats.