What it is
Amatoxins are a family of ring-shaped peptides made by certain mushrooms. The best known, alpha-amanitin, is described in its ChEBI record (via PubChem CID 9543442) as a cyclic peptide of eight amino acid residues with a thioether bridge between a cysteine and a tryptophan. That bridge closes a second ring, so the molecule is a two-ring octapeptide. Its formula is C39H54N10O14S and its molecular weight 919.0.
ChEBI lists three mushrooms that make it: Amanita phalloides (the death cap), Galerina marginata and Conocybe filaris. The death cap also makes a second family of ring peptides, the phallotoxins; the library's phalloidin entry covers the best known of them.
If someone may have eaten a poisonous mushroom, this page is not the place to start. Call emergency services or a poison centre — in the US, the Poison Help line, 1-800-222-1222.
How it poisons
A 2015 review in Food and Chemical Toxicology (PMID 26375431) sets out the mechanism. Alpha-amanitin inhibits RNA polymerase II, the enzyme a cell uses to copy its genes into messages for making proteins. With that enzyme blocked, cells run short of proteins and die. The authors add that other mechanisms are thought to be involved.
The liver is the main target organ; the kidneys are also affected. The review describes the course: symptoms usually appear after a latent period, beginning with gastrointestinal illness and possibly followed by jaundice, seizures and coma, and death in the worst cases. It states that A. phalloides is involved in the majority of fatal mushroom poisonings worldwide.
What the treatment record shows
The same review lists the treatment approach as supportive measures, gastric decontamination, drug therapy and, if the patient worsens, liver transplantation. Its central sentence on drugs is a statement of absence: "The discovery of an effective antidote is still a major unsolved issue."
Silibinin, a compound from milk thistle, is one of the drugs studied in amatoxin poisoning. A PubMed search on 10 November 2026 found 48 records combining amatoxin poisoning with silibinin or silymarin. This entry does not summarise those reports or describe any regimen: they are hospital treatments, and the review's verdict on antidotes stands above them.
Alpha-amanitin in research
Because it kills cells so efficiently, alpha-amanitin is being studied as the toxic payload of antibody-drug conjugates — experimental cancer drugs in which an antibody carries the toxin to tumour cells. A 2024 review in Archives of Toxicology (PMID 38555326) covers this work. No such drug was found approved in this run.
What is not established
- An antidote: none proven (2015 review).
- Which hospital treatments work best: the literature is mostly case series and reviews; this entry does not rank them.
- Safe identification of wild mushrooms: not something a reference page can offer. Lookalikes are a known cause of poisoning.
Where it stands
| Question | Answer as of 2026-11-10 |
|---|---|
| What is it? | Cyclic peptides of eight amino acids; alpha-amanitin is the main one |
| Made by | Death cap and some other mushrooms (ChEBI) |
| Target | RNA polymerase II; liver first, then kidneys |
| Antidote | None proven (Food Chem Toxicol 2015) |
| If exposure is suspected | Emergency services or a poison centre (US: 1-800-222-1222) |
| Advice | None given here |
Related reading
Other natural peptide toxins in the library include phalloidin, from the same mushroom, and bee venom's main peptide. A ring peptide toxin that reaches people through water, not food, is microcystin. The peptide vs. protein entry explains why an eight-residue ring counts as a peptide.