Fd Chem, Toxic. Vol. 20. pp. 265 to 267. 1982 0278-6915 82 030265-03503.00,0 Printed in Great Britain. All rights reserved Copyright © 1982 Pergamon Press Lid THE MUTAGENICITY OF SOME EDIBLE MUSHROOMS IN THE AMES TEST A. VON WRIGHT, J. KNUUTINEN, S. LINDROTH and M. PELLINEN Technical Research Centre of Finland, Food Research Laboratory, Biologinkuja I, SF-02150 Espoo 15 and K.-G. WIDtN and E.-U SEPP:( Department of Pharmacognosy, University of Helsinki, Fabianinkatu 35, SF-O0170 Helsinki 17, Finland (Received 6 November /981: revision received 16 December 1981) Abstract--The mutagenic activity of five wild and two cultivated species of edible mushrooms was studied in the Ames Salmonella/microsome test system. The wild mushrooms tested were four species of the genus Lactarius (L. necator, L. torminosus, L. helvus and L. rufus) and bolete (Boletus edulis). The cultivated species were champignon (Agaricus bisporus) and shiitake (Lentinus edodes). All the mush- rooms were mutagenic to tester strains sensitive to base-pair substitution mutagens, and L. necator, L. rufus and B. edulis also had some frameshift activity. Metabolic activation was not required and the mutagenic activity could be detected even in boiled mushroom extracts. After fractionation with organic solvents (ethanol followed by diethyl ether) the activity was recovered in the ether phase as well as the aqueous phase in the case of L. necator, but remained in the aqueous phase of the A. bisporus and Lentinus edodes extracts. INTRODUCTION The mutagenic activity of some edible wild mush- rooms of the genus Lactarius in the Salmonella typhi- murium tester strains TA100 and TA98 was recently reported (Knuutinen &von Wright, 1982). Because of the relatively large and potentially increasing use of mushrooms as human food, it was considered necess- ary to retest these mushroom species using a more complete set of Ames tester strains and to include in the test programme mushrooms of other genera con- sumed more extensively by man. The additional spe- cies chosen for this study were bolete (Boletus edulis), a highly valued wild mushroom, together with cham- pignon (A#aricus bisporus) and shiitake (Lentinus edodes), the two most important mushroom species in world trade. In addition to direct mutagenicity tests, a study was made of the effect of boiling on the mutagenicity of Lactarius necator, Boletus edulis, Agaricus bisporus and Lentinus edodes. Furthermore, three of the species were extracted with organic solvents to fractionate the mutagenic agents. EXPERIMENTAL Test materials. Samples of the Lactarius species investigated (L. necator, L. torminosus, L. helous and L. rufus) were gathered in September 1980 in South- ern Finland. Agaricus bisporus and Lentinus edodes were obtained from the experimental mushroom-cul- tivation plant of the Food Research Laboratory of the Technical Research Centre of Finland. Samples of Boletus edulis were kindly provided by Valio, the Fin- nish Co-operative Dairies' Association. All the mush- rooms were stored at -20°C. 265 Preparation of crude mushroom extracts. The frozen mushrooms were homogenized in a Bamix M-100 household homogenizer. The homogenate was filtered and the filtrate was centrifuged to remove any remaining mushroom debris. The supernatant was sterilized by filtration through a Sartorius (0.45/am) filter (Sartorius GmbH, Grttingen, FRG) and was used immediately for mutagenicity tests. About 60 ml mushroom extract was obtained from each 100g of mushrooms. mushrooms extraction with ethanol ethanol extract concentration in vacuum aqueous phasel ~ ~shaking with ether aqueous phase I! ether phase I concentration in vacuum ether extract ~/ ~ shaking with 5% Na2CO 3 aqueous phase III ether phase II Fig. I. Fractionation scheme for the mutagenic agents in mushrooms. Sliced mushrooms (1 kg) were incubated in l kg 99% ethanol at room temperature for 72 hr. The etha- nol extract was collected, filtered and evaporated in a vacuum evaporator (Heidolph Elektro KG, Kelheim. FRG) to yield aqueous phase I (about 300 ml). This was shaken with an equal volume of diethyl ether, the phases were separated and each was concentrated in a vacuum to about 50ml (aqueous phase II and ether phase 1). Ether phase I .was shaken with 100 ml 5°,,; Na2COa solution to yield ether phase II and aqueous phase II!. The latter was concentrated to half of the original volume and neutralized with 1 s-HCI before the mutagenicity tests.