The species is now known to contain two main groups of toxins, both multicyclic (ring-shaped) peptides, spread throughout the mushroom tissue: the amatoxins and the phallotoxins. Another toxin is phallolysin, which has shown some hemolytic (red blood cell–destroying) activity in vitro. An unrelated compound, antamanide, has also been isolated.
Amatoxins consist of at least eight compounds with a similar structure, that of eight amino-acid rings; they were isolated in 1941 by Heinrich O. Wieland and Rudolf Hallermayer of the University of Munich (Litten 1975). Of the amatoxins, α-amanitin is the chief component and along with β-amanitin is likely responsible for the toxic effects (Köppel 1993; Dart 2004). Their major toxic mechanism is the inhibition of RNA polymerase II, a vital enzyme in the synthesis of messenger RNA (mRNA), microRNA, and small nuclear RNA (snRNA). Without mRNA essential protein synthesis and hence cell metabolism grind to a halt and the cell dies (Karlson-Stiber & Persson 2003). The liver is the principal organ affected, as it is the organ which is first encountered after absorption in the gastrointestinal tract, though other organs, especially the kidneys, are susceptible (Benjamin 1995). The RNA polymerase of Amanita phalloides is insensitive to the effects of amatoxins; as such, the mushroom does not poison itself (Horgen et al. 1978).
The phallotoxins consist of at least seven compounds, all of which have seven similar peptide rings. Phalloidin was isolated in 1937 by Feodor Lynen, Heinrich Wieland's student and son-in-law, and Ulrich Wieland of the University of Munich. Though phallotoxins are highly toxic to liver cells (Wieland & Govindan 1974), they have since been found to have little input into the death cap's toxicity as they are not absorbed through the gut (Karlson-Stiber & Persson 2003). Furthermore, phalloidin is also found in the edible (and sought-after) Blusher (Amanita rubescens) (Litten 1975). Another group of minor active peptides are the virotoxins, which consist of six similar monocyclic heptapeptides (Vetter 1998). Like the phallotoxins they do not exert any acute toxicity after ingestion in humans(Karlson-Stiber & Persson 2003).References
- Benjamin, Denis R. (1995). Mushrooms: poisons and panaceas — a handbook for naturalists, mycologists and physicians. New York: WH Freeman and Company.
- Dart, RC (2004). "Mushrooms", Medical toxicology. Philadelphia: Williams & Wilkins, 1719–35.
- Horgen, Paul A.; Allan C. Vaisius and Joseph F. Ammirati (1978). "The insensitivity of mushroom nuclear RNA polymerase activity to inhibition by amatoxins". Archives of Microbiology 118 (3): 317–9.
- Karlson-Stiber C, Persson H (2003). "Cytotoxic fungi - an overview". Toxicon 42 (4): 339-49.
- Köppel C (1993). "Clinical symptomatology and management of mushroom poisoning". Toxicon 31 (12): 1513–40.
- Litten, W. (March 1975). "The most poisonous mushrooms". Scientific American 232 (3): 90–101.
- Vetter, János (January 1998). "Toxins of Amanita phalloides". Toxicon 36 (1): 13–24.
- Wieland T, Govindan VM (1974). "Phallotoxins bind to actins". FEBS Lett. 46 (1): 351-3.
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