Amanita muscaria: chemistry, biology, toxicology, and ethnomycology
Didier MICHELOT, Leda Maria MELENDEZ-HOWELL
Mycological Research, 2003, 107, (2), 131-146.
The fly agaric is a remarkable mushroom in many respects; these are its bearing, history, chemical components and the poisoning that it provokes when consumed. The ‘pantherina’ poisoning syndrome is characterized by central nervous system dysfunction. The main species responsible are Amanita muscaria and A. pantherina (Amanitaceae) ; however, some other species of the genus have been suspected for similar actions. Ibotenic acid and muscimol are the active components, and probably, some other substances detected in the latter species participate in the psychotropic effects. The use of the mushroom started in ancient times and is connected with mysticism. Current knowledge on the chemistry, toxicology, and biology relating to this mushroom is reviewed, together with distinctive features concerning this unique species.
The fly agaric, Amanita muscaria, and the panther, A. pantherina, are the species mainly involved in the
‘pantherina-muscaria’ poisoning syndrome. Poisoning cases are sometimes accidental and mainly those caused by A. pantherina, since this mushroom might be mistaken for some other species ; but, in some cases, intentional consumption of A. muscaria occurs for recreational purposes. Prognosis of the poisoning is generally minor; although, very seldom lethal cases are mentioned. Central nervous system dysfunctions primarily characterize this poisoning. This review describes the unusual features associated with these species, medical, chemical, pharmacological, historical and phytogeographical and aims to synthesize current knowledge on these matter. The emphasis is, however, the chemical and biological properties of the substances found in the mushroom.
THE SUSPICIOUS SPECIES
Detailed mycological data have already been published (Moser 1983, Bresinsky & Besl 1990, Takashi, Chihiro & Mitsuya 1999, Ne´ ville & Poumarat 2001). The main responsible species are Amanita muscaria (Fig. 1) and A. pantherina. The cap of A. muscaria can be 50 cm diam and bright red, orange, or even orange or yellow, apart from the white fleck. Many species of the A. muscaria complex bear so-called crassospores (Tulloss & Halling 1997). The species cannot be mistaken for any other perhaps except the edible A. caesarea. A. pantherina is also known as: ‘panther cap’, ‘panther Amanita’, ‘panther agaric’ (North America), ‘pantherschwamm’, ‘kroˆ tenschwamm’ (Germany), ‘tignosa’ (Italy), ‘pantera’, ‘pixaca’, ‘hongo loco’, ‘hongo malo’ (Spanish America) and ‘amanite panthe`re’ (French). The cap of A. pantherina is 5–10 cm diam and grey or grey-brown, grey yellow, paling when old, with small pure white flakes. This species, in some accidental poisoning cases, has been mistaken for the edible A. rubescens and A. spissa. These two species occur in many continents (Ne´ ville & Poumarat 2001) and grow
in deciduous woods, especially beech and birch, and also coniferous ones (Hotson & Lewis 1934).
Some related species are suspected of poisoning or produce the active components detected in these fungi (Bresinsky & Besl 1990): A. regalis (Elonen, Tarssanen & Ha¨ rko¨ nen 1979) and A. strobiliformis (Takemoto, Yokobe & Nakajima 1964; syn. A. solitaria auct.). A few cases of poisoning by A. gemmata (Cornue´ 1961; syn. A. junquillea), A. crenulata (Buck 1965, Tulloss 1990), and A. cothurnata have also been reported, but their possible toxic potencies are disputed (Chilton & Ott 1976). Toxin content has been suggested to be intraspecific variation (Benedict, Tyler & Brady 1966). Surprisingly, Chilton & Ott (1976) mentioned large amounts of chlorocrotylglycine and amino-2-hexadien- 4,5-oic acid, both derivatives of glycine, in A. smithiana. Noting the functional identity (‘toxicophore’) of these latter substances, an enzyme inhibitor activity has to be suspected; nephrotoxic poisonings by this species have been reported (Leathem et al. 1997).