Agaritine content of 53 Agaricus species collected from nature.

Fifty-three different species of the genus Agaricus were collected in the Czech Republic during the period 1998-2001 and identified by an experienced mycologist. The samples were analysed for agaritine (N2-(gamma-L-glutamyl)-4-hydroxymethylphenylhydrazine) content, a precursor to a suspected rodent carcinogen. There was a huge variation in agaritine content between species, but less variation between samples of a species. Whereas the cultivated mushroom Agaricus bisporus commonly contain 200-500 mg agaritine kg(-1) fresh weight, no less than 24 of the 53 species contained agaritine levels above 1000 mg kg(-1) fresh weight. The highest level was found in A. elvensis containing up to 10, 000 mg kg(-1) fresh weight. Twenty species contained intermediate levels (100-1000 mg kg(-1)), and nine species were below 100 mg kg(-1). Some of the species producing low levels of agaritine might be candidates for future strain development of Agaricus mushrooms for cultivation. No correlation could be observed between agaritine content and size of the mushroom, week of the year when collected, year of collection, or site of collection. Besides occurring in the genus Agaricus, some species of the genera Leucoagaricus and Macrolepiota were also shown to contain agaritine.