Amanullin is a cyclic nonribosomal peptide. It is an amatoxin, all of which are found in several members of the Amanita genus of mushrooms. The oral LD50 of amanullin is approximately 20 mg/kg in mice, however it is non-toxic in humans. Like other amatoxins, amanullin is an inhibitor of RNA polymerase II. Amanullin has a species dependent and specific attraction to the enzyme RNA polymerase II. Upon ingestion, it binds to the RNA polymerase II enzyme, effectively causing cytolysis of hepatocytes (liver cells). Amanullin, a non-toxic component, having an oxygen-free isoleucine side chain no. 3, exhibits an inhibitory effect on RNA polymerase II about two orders of magnitude smaller than that of gamma-amanitin. An equal, relatively weak, inhibitory effect has previously been found with the synthetically obtained Ile3-analog 7.
-O828.gif)