Mutagenic and genotoxic activities of extracts derived from the cooked and raw edible mushroom Agaricus bisporus.

A. bisporus has been reported to be carcinogenic to mice [Toth et al. (1986) Cancer Res 38:177-180] and mutagenic in Salmonella typhimurium [Sterner et al. (1982) Mutat Res 101:269-281]. The effects of different heat treatments on the mutagenicity of raw, cooked (boiled) and fried A. bisporus extracts in the S. typhimurium test is reported. The spectrum of potential mutagenic activity of A. bisporus extracts was tested in vitro in Syrian hamster embryo cells for selective DNA amplification and in primary rat hepatocytes for DNA single-strand breaks. DNA single-strand breaks were also determined in liver cells of rats and micronuclei were measured in bone marrow cells of mice in vivo following oral application of A. bisporus extracts. It was shown that the complex A. bisporus extracts per se are not detectably mutagenic in S. typhimurium and that the previously observed increase in number of colonies per plate is probably due to a histidine artefact. No indication of genotoxicity was seen in the two in vitro assays with primary mammalian cells with two different end points. No evidence of in vivo genotoxic effects was observed in the rat liver cells. Finally, A. bisporus was not genotoxic in the micronucleus assay of mouse bone marrow cells in contrast to its previously reported carcinogenicity in mice.