Mutagenic and antimutagenic factor(s) extracted from a desert mushroom using different solvents.

A desert mushroom called Al-faga (Tirmania pinoyi) was sequentially extracted with boiling water, chloroform and ethanol under reflux conditions. The water extract was freeze-dried while the organic solvents were fully evaporated to obtain residues, which were redissolved in dimethylsulphoxide and then tested for mutagenicity in the Ames assay using the Salmonella tester strains TA98 and TA100. The aqueous extract failed to show any mutagenic activity while the chloroform extract proved to be mutagenic with and without metabolic activation. The ethanol extract was not mutagenic in the same tests. However, ethanol extract combined with known carcinogens like benzo[a]pyrene or 7,12-dimethyl-benz[a]anthracene (with metabolic activation) inhibited the carcinogen-induced mutagenicity in a dose-dependent manner. These results show that both mutagens and antimutagens may be extracted from a single food item by using different solvents.