The Amanita Phalloides, commonly known as Agaricus Phalloides or Tignosa Warbler, is a widespread deadly fungus and is probably the most dangerous that exist in nature due to its high polymorphism, which makes it similar to many species, congeners and not (hence the popular names: death cap and exterminating angel).
Harmful factors of the fungus:
• Amatoxin (four types of Amanitin: α, β, γ and ε), cyclic molecules (containing eight amino-acid rings) that selectively block RNA polymerase II, involved in protein synthesis (fundamental enzyme in the synthesis of mRNA, snRNA and microRNA).
• Phallotoxin (which the most common is the Phalloidin [MW 1000 D]), is another type of bicycle heptapeptide equally harmful to the cell membrane, because they bind with the F-actin, structural protein that keeps in position the ion channels: thus escaping, from the cell, sodium ions and entering potassium ions (the cell then swells up to lyse). So stabilizes this molecule (actin filaments) preventing their depolarization and this process is also favored by the interaction with the enzyme that hydrolyzes ATP; blocks the cytoplasmic movement, making the hepatocyte membrane more permeable.
Also interacts with G-actin and promotes its polymerization.
• Phallolysin : another Phallotoxin, it has hemolytic properties on erythrocytes in vitro.
• Toxophallin: it’s also a Phallotoxin; has no immediate effect on target cells because it isn’t mediated by receptor, but causes damage to the nuclear level of the affected cell: we see a condensation of chromatin with a breakdown of the nuclear membrane, a typical feature of apoptosis.
A new highly toxic protein isolated from the death cap Amanita phalloides is an L-amino acid oxidase, Pub Med
Amatoxin and Phallotoxin are heat stable toxins and therefore even after cooking, the mushroom is still deadly.
• Antamanide : is a cyclic decapeptide, which can react with the alkali metals and this includes sodium and calcium complex. It also inhibits the MPTP (mitochondrial permeability transition pore) taking relationship with the pores control complex Cyclophilin-D (CyP-D).
This protein (Antamanide) was already known in the past for its anti-toxin action against Phallotoxin and Amatoxin because it works on the same hepatocyte’s receptor (identified as FK506), but with antagonist function of the two toxins.
In recent laboratory tests, it was found different bioactivity of this molecule: an inhibitory effect on tumor cells growth in vitro, displays an antitumor action in animal models and an attenuates IL-2-induced multisystem organ edema. Furthermore, it’s still under study due to disease caused by abnormal function of MPTP, including neurodegenerative disease, muscular dystrophies (muscle weakness), hepatotoxicity by oxidation and damage to the ischemic kidney: it could be a cure of these.
Antamanide, a Derivative of Amanita phalloides, Is a Novel Inhibitor of the Mitochondrial Permeability Transition Pore, Pub Med
Causes irreversible liver damage and death. Even tiny fragments can be lethal (about one milligram per kilogram of person’s weight who ingests). The RNA-polymerase in the liver are inhibited: so protein synthesis stop and it has hepatic necrosis, with similar effects of severe viral hepatitis. There is an accumulation of albumin in hepatocyte: this is given by increased membrane permeability caused by the action of Phalloidin on the actin.
Symptoms and course of disease:
The first symptoms of the Phalloid Syndrome can be felt after about 12-24 or 48 hours after ingestion, depending on the physical constitution of the subject, and the symptoms come in the form of abdominal pain, vomiting, diarrhea, dehydration, hypotension, tachycardia, hypoglycemia, acid-base disturbances, thirstiness and lack of urine. After 3 days or so, if the patient survives these initial symptoms, may show signs of improvement, but at this period usually follows a rapid and severe loss of strength, prostration and insomnia caused by pain. Death may occur within 48 hours (high dose) in 50/90 % of cases from progressive and irreversible damage to the liver, kidney, heart and muscles; but the disease typically lasts 6 to 8 days in adults and 4 to 6 days in children.
Two or three days after the beginning of the last phase, jaundice, cyanosis and lowering the temperature come out. Death usually follows a period of coma and occasionally convulsions. If you improve, it generally requires at least a month, and is accompanied by hepatomegaly.
By ingestion of this type of fungus is required hospitalization. We can adopt four different therapy strategies depending on the stage of the Phalloid disease.
Primary health care: use of gastric lavage and activated charcoal.
Supportive measures: patients who arrive after a few hours of ingestion, it’s necessary to implement a therapy for hydration, correction of metabolic acidosis, hypoglycemia, electrolyte balance and clotting.
Specific treatments: unfortunately there is still no available definitive antidote, but rather specific therapies can be implemented as:
- Intravenous Penicillin G, and according to recent research the Cephalosporins would benefit;
- Intravenous Silibinin, an extract of the plant Silybum Marianum, this prevents the effect of Amanitin, blocking the entrance inside the hepatocyte;
- Intravenous N-acetylcysteina, is a precursor of glutathione: this was seen to be consumed all by Amanitin causing oxidative damage.
Other methods may be used for the toxins’ elimination in severe cases, for example the use of hemodialysis, blood transfusions, plasmapheresis and peritoneal dialysis.
In critically ill patients, the only solution is liver transplantation.
Amanita Phalloide and Cancer:
During the last years, an increasing number of studies identify as possible cancer treatment the injection of fungus’ toxic substances directly inside the tumor.
It was mentioned for example, the role of Antamanide (AA) as antitumor. This acts at the level of MPTP on the pores control complex Cyclophillin-D (CyP-D), which at first glance would seem to favor the tumor, since it doesn’t allows the apoptosis (programmed death) of a cell now compromised. However Cyp-D modulates a variety of cell processes, including gene transcription, proliferation, survival, chemotaxis and motility, targeting molecules as diverse as the transcription factor NF-AT, MAP kinase upstream regulators, the membrane receptors CD147 and CXCR4, and the kinases Itk, Crk and Jak2. It’s a field still largely unknown but certainly can be help in the weakening of the tumor and try to stop its growth.
The knowledge of cancer’s genetics combined with that of Amatoxin has made possible a meeting point in view of treatment for cancer. It’s known that in tumors HOX genes’ family (basis genes of the human genome) is hyper-express from which it’s transcribed, between the various enzymes, RNA-Polymerase II. The toxin, as already said, is able to lock it and it’s on this point that we tried to direct searches. It was found, by a research on B-Cell Chronic Lymphocytic Leukemia (B-CLL) that the use of amanitin, addition to stop the metabolism and the growth of these cancerous cells, does change their immunological structure, so as to be more easily recognizable to other cells of our immune system. A very innovative discovery that has given as final result tumor regression in 21 months after initial administration, without the use of radio and chemotherapy.
Tumor Therapy with Amanita phalloides (Death Cap): Stabilization of B-Cell Chronic Lymphatic Leukemia, Pub Med
A latest recently research, completed in 2012, that leaves many doors open on this kind of work, is that practiced by the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), who obtained positive results in regression of tumors, including those of pancreas, breast, prostate and bile ducts.
It’s observed that tumors express more epithelial membrane protein called EpCAM, and this was the door to make a breach in the tumor through the use of monoclonal antibodies conjugated with the α-amanitin (Each antibody is linked to between four and eight toxin molecules. Amanitin is regarded as very suitable for this purpose. It is small enough not to be recognized as foreign by immune cells, while it is also robust enough to lend itself to chemical conjugation).
During tests on cultured cells, the poison was effective destroying diseased cells. In a second test, carried out on animal model, it was discovered that in mice bearing human pancreatic tumor, a single injection was able to inhibit tumor growth. Two additional injections with higher doses of the toxin have finally resulted in complete tumor regression in 90 % of mice sick.
Another series of tests was acted to verify the possible toxicity of higher doses of venom on the liver, shown that there weren’t adverse effects.
Treatments with unconjugated antibodies against EpCAM have already been tested in clinical trials such as for breast cancer. They were intended to attack the cancer solely with the weapons of the immune system, but they turned out to be clinically ineffective.
Death cap mushroom poison to arrest pancreatic cancer in mice, DKFZ