Amaninamide

Amaninamide is a cyclic peptide. It is one of the amatoxins, all of which are found in several members of the mushroom genera "Amanita", "Lepiota" and "Galerina". It differs from alpha-amanitin in lacking the hydroxyl group on tryptophan. This alters its UV absorption spectrum but not its toxicity.
Toxicology.
Like other amatoxins, amaninamide is an inhibitor of RNA polymerase II. Upon ingestion, it binds to the RNA polymerase II enzyme which completely prevents mRNA synthesis, effectively causing cytolysis of hepatocytes (liver cells) and kidney cells.