Muscarine

Muscarine, L-(+)-muscarine, or muscarin is a natural product found in certain mushrooms, particularly in Inocybe and Clitocybe species, such as the deadly C. dealbata. Mushrooms in the genera Entoloma and Mycena have also been found to contain levels of muscarine which can be dangerous if ingested. Muscarine has been found in harmless trace amounts in the genera Boletus, Hygrocybe, Lactarius and Russula. Trace concentrations of muscarine are also found in Amanita muscaria, though the pharmacologically more relevant compound from this mushroom is the gabaergic drug muscimol. A. muscaria fruitbodies contain a variable dose of muscarine, usually around 0.0003% of total fresh weight. This is very low and toxicity symptoms occur very rarely. Highly toxic Inocybe and Clitocybe species contain muscarine concentrations up to 1.6%. Muscarine is a selective agonist of the muscarinic acetylcholine receptors.