Amatoxin

Toxic compounds found in certain mushrooms

Amatoxins

Amanita phalloides, commonly known as the death cap, is a mushroom that contains amatoxins.

Amatoxins are a group of highly toxic compounds found in several species of mushrooms, most notably in the genera Amanita, Galerina, and Lepiota. These toxins are responsible for the majority of fatal mushroom poisonings worldwide. The most infamous of these mushrooms is the Amanita phalloides, commonly known as the death cap.

Chemical Structure and Function

Amatoxins are bicyclic octapeptides, meaning they are composed of eight amino acids arranged in a double-ring structure. This unique configuration allows them to bind tightly to the enzyme RNA polymerase II, inhibiting its function. RNA polymerase II is crucial for transcription, the process by which DNA is copied into messenger RNA (mRNA). By blocking this enzyme, amatoxins effectively halt protein synthesis, leading to cell death.

Toxicity and Symptoms

The ingestion of amatoxin-containing mushrooms can lead to severe poisoning. Symptoms typically appear 6 to 12 hours after consumption and include abdominal pain, vomiting, and diarrhea. These initial symptoms may subside temporarily, giving a false sense of recovery. However, within 24 to 48 hours, severe liver and kidney damage can occur, potentially leading to liver failure and death if not treated promptly.

Treatment

Alpha-Amanitin RNA_polymerase II complex

There is no specific antidote for amatoxin poisoning, but early medical intervention can improve outcomes. Treatment typically involves supportive care, including intravenous fluids and electrolytes to manage dehydration and electrolyte imbalances. Activated charcoal may be administered to reduce toxin absorption if the patient presents early. In some cases, silibinin, a compound derived from milk thistle, is used to protect the liver and inhibit toxin uptake.

Prevention

The best way to prevent amatoxin poisoning is to avoid consuming wild mushrooms unless they have been positively identified by an expert. Many edible mushrooms have toxic look-alikes, making identification challenging for the untrained eye. Education and awareness are key in preventing accidental ingestion.

Related pages

• Mushroom poisoning
• Amanita phalloides
• RNA polymerase II
• Liver failure