Coprine
Coprine is a mycotoxin. It was first isolated from common inkcap. It occurs in mushrooms in the genus Coprinopsis, specifically within sections Alopeciae, Atramentariae, and Picaceae. When combined with alcohol, it causes "Coprinus syndrome". It inhibits the enzyme aldehyde dehydrogenase, which is involved in the metabolism of alcohol. This inhibition leads to a buildup of acetaldehyde, causing an alcohol flush reaction. Because of this, the mushroom is commonly referred to as '''Tippler's Bane.'''
History
Because of the similarities to disulfram poisoning, it was long speculated that disulfram could actually be produced by fungi. In 1956 it was reported that disulfram had been isolated from coprinus, but this finding could not be replicated. In 1975, coprine was identified as the compound in the common inkcap, with the mechanism identified in 1979.Symptoms
Symptoms of coprine poisoning include facial reddening/flushing, nausea, vomiting, malaise, agitation, palpitations, tingling in limbs, and sometimes headache and excessive salivation. This can be described as the alcohol flush reaction. Symptoms typically arise five to ten minutes after consumption of alcohol. If no more alcohol is consumed, the symptoms will generally subside over two to three hours, and symptom severity is proportional to the amount of alcohol consumed. Consumption of alcohol can induce these symptoms for up to 5 days after ingesting coprine. Interestingly, symptoms of coprine poisoning do not appear when the mushroom is ingested raw, but only when the mushroom is cooked.In examining coprine poisoning cases in Germany in 2010, none of the patients died, and all made full recoveries after abstaining from alcohol. In one case medical care was not sought at all, and while there was a range in time of ethanol consumption after mushroom consumption, all the cases had well-cooked the mushrooms before ingestion.
The symptoms of coprine poisoning and alcohol consumption are similar to those induced by disulfiram, a drug utilized to treat chronic alcoholism by inducing severe side-effects to alcohol consumption. Because of this, research was done into the use of coprine as a similar drug for alcoholism. However, testing has shown coprine to have long-term mutagenic and reproductive effects, making it ill-suited for long-term use.
Mechanism of action
Coprine is a hydrolytic prodrug of 1-aminocyclopropanol which is a covalent inhibitor of the enzyme aldehyde dehydrogenase. 1-aminocyclopropanol quickly converts to a reactive diol known as cyclopropanone hydrate, which binds covalently to the thiol present in the active site of the enzyme, deactivating the dehydrogenase activity. This inhibition then causes a buildup of acetaldehyde if ethanol is ingested. Since acetaldehyde is toxic and can no longer be metabolized to the less toxic acetic acid, the characteristic symptoms of coprine poisoning occur. However, as shown in the mechanism below, the covalent bonding is reversible, which is what allows symptoms to subside if no more alcohol is consumed.1-Aminocyclopropanol also deactivates the esterase activity of aldehyde dehydrogenase, but less significantly.